| Genus |
Order |
Reference |
Note |
Nomenclature |
| M | |
| Maackia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Maasella | Alcyonacea | Bayer (1981) | Paralcyoniidae. | ICZN |
| Mabea | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Mabrya | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Maburea | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Mabuya | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Macaca | Primates | McKenna & Bell (1997) | . | ICZN |
| Macadamia | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Macairea | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Macandrewia | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Macandrewiidae. | ICZN |
| Macaranga | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Macarenia | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Macarisia | Malpighiales | Mabberley (2008) | Rhizophoraceae. | ICBN |
| Macarthuria | Caryophyllales | Mabberley (2008) | Limeaceae. | ICBN |
| Macbridea | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Macbrideina | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Macbrideola | Stemonitales | Yamamoto (1998) | . | ICBN |
| Maccabeus | Seticoronaria | Adrianov & Malakhov (1996) | . | ICZN |
| Macellibacteroides | Bacteroidales | Jabari et al. (2012) | . | ICNB |
| Macgregonria | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Macgregorella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Macgregoria | Passeriformes | Clements (2007) | . | ICZN |
| Machadoella | Neogregarinorida | Perkins et al. (2000) | . | ICZN |
| Machadosentis | Gyracanthocephala | Noronha (1992) | Quadrigyridae. | ICZN |
| Machaeranthera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Machaerina | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Machaerirhynchus | Passeriformes | Clements (2007) | . | ICZN |
| Machaerium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Machaeropterus | Passeriformes | Clements (2007) | . | ICZN |
| Machairophyllum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Machaonia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Macheiramphus | Falconiformes | Clements (2007) | . | ICZN |
| Machetornis | Passeriformes | Clements (2007) | . | ICZN |
| Macholophus | Passeriformes | Clements (2007) | . | ICZN |
| Mackaya | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Mackenziaena | Passeriformes | Clements (2007) | . | ICZN |
| Mackinlaya | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mackinnonia | Protococcidiorida | Perkins et al. (2000) | . | ICZN |
| Maclaudia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Macleania | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Macleaya | Ranunculales | Mabberley (2008) | Papaveraceae. | ICBN |
| Macledium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Maclura | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Maclurochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Maclurodendron | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Maclurolyra | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Macodes | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Macoubea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Macowania | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Macphersonia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Macracanthorhynchus | Oligacanthorhynchida | Amin (1985) | . | ICZN |
| Macrachaenium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Macradenia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Macranthera | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Macrelaps | Squamata | Vitt & Caldwell (2009) | Serpentes. Atractaspididae. | ICZN |
| Macroagelaius | Passeriformes | Clements (2007) | . | ICZN |
| Macrobiotus | Parachela | Kinchin (1994) | . | ICZN |
| Macrocalamus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Macrocarpaea | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Macrocarpus | Nemaliales | Lin et al. (2011) | . | ICBN |
| Macrocentrum | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Macrocephalon | Galliformes | Clements (2007) | . | ICZN |
| Macrochaetus | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Macrochelys | Testudinata | Vitt & Caldwell (2009) | Chelydridae. | ICZN |
| Macrochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Macroclinidium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Macrocnema | Actiniaria | Fautin et al. (2007) | Junior homonym, but no replacement name was published. | ICZN |
| Macrocnemum | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Macrococculus | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Macrococcus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Macrocoleps | Prorodontida | Lynn (2008) | . | ICZN |
| Macrocolura | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Macrocoma | Orthotrichales | Goffinet et al. (2009) | . | ICBN |
| Macrocytopharynx | | Lynn (2008) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Ciliophora. | ICZN |
| Macrodactyla | Actiniaria | Fautin et al. (2007) | Junior homonym, but no replacement name was published. | ICZN |
| Macrodasys | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Macroderma | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Macrodictyum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Macrodiplophyllum | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Macrodipteryx | Caprimulgiformes | Clements (2007) | . | ICZN |
| Macroditassa | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Macrogalidia | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Macrogenioglottus | Anura | Vitt & Caldwell (2009) | Cycloramphidae. | ICZN |
| Macroglossus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Macrohasseltia | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Macrohymenium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Macrolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Macrolenes | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Macrolobium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Macromeles | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Macromeria | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Macromitrium | Orthotrichales | Goffinet et al. (2009) | . | ICBN |
| Macromonas | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Macronectes | Procellariiformes | Clements (2007) | . | ICZN |
| Macronous | Passeriformes | Clements (2007) | . | ICZN |
| Macronyx | Passeriformes | Clements (2007) | . | ICZN |
| Macropanax | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Macropeplus | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Macroperipatus | Euonychophora | Peck (1975) | Peripatidae. | ICZN |
| Macropharynx | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Macropholidus | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Macrophyllum | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Macropidia | Commelinales | Mabberley (2008) | Haemodoraceae. | ICBN |
| Macropiper | Piperales | Mabberley (2008) | Piperaceae. | ICBN |
| Macropodanthus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Macropodiella | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Macropodina | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Macropodinium | Macropodiniida | Lynn (2008) | . | ICZN |
| Macropodium | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Macroprotodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Macropsalis | Caprimulgiformes | Clements (2007) | . | ICZN |
| Macropteranthes | Myrtales | Mabberley (2008) | Combretaceae. | ICBN |
| Macroptilium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Macropus | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Macropygia | Columbiformes | Clements (2007) | . | ICZN |
| Macrorhynchia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Macrosamanea | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Macroscelides | Macroscelidea | McKenna & Bell (1997) | . | ICZN |
| Macroscepis | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Macroscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Macroselinum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Macrosolen | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Macrospermum | Nostocales | Komarek (2008) | . | ICBN |
| Macrosphenus | Passeriformes | Clements (2007) | . | ICZN |
| Macrosphyra | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Macrospironympha | Trichonymphida | Cepicka et al. (2010) | . | ICZN |
| Macrostylis | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Macrosyringion | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Macrotarsomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Macrothamniella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Macrothamnion | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Macrothamnium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Macrothelypteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Macrotis | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Macrotorus | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Macrotrachela | Bdelloida | Segers (2002); Segers (2007) | . | ICZN |
| Macrotrichomonas | Cristamonadida | Cepicka et al. (2010) | . | ICZN |
| Macrotus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Macrotyloma | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Macroversum | Parachela | Kinchin (1994) | . | ICZN |
| Macrovipera | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Macrozamia | Cycadales | Mabberley (2008); Christenhusz et al. (2011) | . | ICBN |
| Macruromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Macvaughiella | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Macvicaria | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Madagascaria | Erythropeltidales | Wynne & Schneider (2010) | . | ICBN |
| Madagascarophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Madagasikaria | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Madagaster | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Madanga | Passeriformes | Clements (2007) | . | ICZN |
| Maddenia | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Madecassophryne | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Madhuca | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Madia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Madlabium | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Madoqua | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Madracis | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Madrepora | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Madromys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Madsenia | Philasterida | Lynn (2008) | . | ICZN |
| Maeotias | Limnomedusae | Bouillon et al. (2006) | . | ICZN |
| Maerua | Brassicales | Mabberley (2008) | Capparaceae. | ICBN |
| Maesa | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Maesobotrya | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Maesopsis | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Maeviella | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Maferria | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Magadania | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Magdalenaea | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Maghrebia | Arcellinida | Meisterfeld (2000) | Difflugina -- Difflugiidae. | ICZN |
| Magnalembus | Philasterida | Lynn (2008) | . | ICZN |
| Magnesoina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Prolixoplectidae. | ICZN |
| Magnetobacterium | Nitrospirales | Garrity et al. (2005) | . | ICNB |
| Magnetospira | Rhodospirillales | Williams et al. (2012) | . | ICNB |
| Magnetospirillum | Rhodospirillales | Garrity et al. (2005) | . | ICNB |
| Magnifolliculina | Heterotrichida | Lynn (2008) | nomen nudum. | ICZN |
| Magnistipula | Malpighiales | Mabberley (2008) | Chrysobalanaceae. | ICBN |
| Magnolia | Magnoliales | Mabberley (2008) | Magnoliaceae. | ICBN |
| Magodendron | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Magonia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Maguireanthus | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Maguireocharis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Maguireothamnus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Magydaris | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Maharanga | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Mahawoa | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mahella | Thermoanaerobacterales | Bonilla Salinas et al. (2004); Ludwig et al. (2009) | . | ICNB |
| Mahua | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Mahurea | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Maianthemum | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Maidenia | Alismatales | Mabberley (2008) | Hydrocharitaceae. | ICBN |
| Maieta | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Maihuenia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Maingaya | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Maireana | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Mairetis | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Mairia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Majidea | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Makalata | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Makedia | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Makinoa | Fossombroniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Makinoella | Chlorellales | Pažoutová et al. (2010) | As Oocystis-clade or Oocystaceae. | ICBN |
| Malacacanthus | Alcyonacea | Bayer (1981) | Alcyoniidae. | ICZN |
| Malachra | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Malaclemys | Testudinata | Vitt & Caldwell (2009) | Emydidae. | ICZN |
| Malacobdella | Eumonostilifera | Gibson (1995); Chernyshev (2003); Thollesson & Norenburg (2003); Kajihara et al. (2008) | Malacobdellidae. | ICZN |
| Malacobelemnon | Pennatulacea | Williams (1995) | . | ICZN |
| Malacocarpus | Sapindales | Mabberley (2008) | Nitrariaceae. | ICBN |
| Malacocera | Caryophyllales | Mabberley (2008) | Chenopodiaceae. | ICBN |
| Malacochersus | Testudinata | Vitt & Caldwell (2009) | Testudinidae. | ICZN |
| Malacocincla | Passeriformes | Clements (2007) | . | ICZN |
| Malacomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Malaconema | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Malaconotus | Passeriformes | Clements (2007) | . | ICZN |
| Malacophrys | | Lynn (2008) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Ciliophora - Class Prostomatea. | ICZN |
| Malacopteron | Passeriformes | Clements (2007) | . | ICZN |
| Malacoptila | Galbuliformes | Clements (2007) | . | ICZN |
| Malacoraja | Rajiformes | Nelson (2006) | . | ICZN |
| Malacorhynchus | Anseriformes | Clements (2007) | . | ICZN |
| Malacosaccus | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Malacothamnus | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Malacothrix | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Malacothrix | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Malagasia | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Malagazzia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Malamoeba | | Rogerson & Patterson (2000); Smirnov et al. (2005) | Domain Eucarya - Phylum Amoebozoa. | ICZN |
| Malanea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Malania | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Malawimonas | Malawimonadida | Cavalier-Smith (2003) | . | ICZN |
| Malawispongia | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Malaxis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Malayemys | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Malcolmia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Malcorus | Passeriformes | Clements (2007) | . | ICZN |
| Malephora | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Malesherbia | Malpighiales | Mabberley (2008) | Malesherbiaceae. | ICBN |
| Malia | Passeriformes | Clements (2007) | . | ICZN |
| Malikia | Burkholderiales | Spring et al. (2005) | . | ICNB |
| Malimbus | Passeriformes | Clements (2007) | . | ICZN |
| Malleastrum | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Malleodendron | Heterogloeales | Ettl (1978) | . | ICBN |
| Malleola | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Malleostemon | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Mallomonas | Synurales | Kristiansen & Preisig (2001) | Mallomonadaceae. | ICBN |
| Mallomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Mallophyton | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Mallotonia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Mallotus | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Malmea | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Malmeanthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Malonomonas | Desulfuromonales | Garrity et al. (2005) | . | ICNB |
| Malope | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Malouetia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Malpaisomys | Rodentia | Musser & Carleton (2005) | Recently extinct. | ICZN |
| Malperia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Malpighamoeba | | Rogerson & Patterson (2000); Smirnov et al. (2005) | Domain Eucarya - Phylum Amoebozoa. | ICZN |
| Malpighia | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Malpighiantha | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Malpolon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Maltebrunia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Malurus | Passeriformes | Clements (2007) | . | ICZN |
| Malus | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Malva | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Malvastrum | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Malvella | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Mameliella | Rhodobacterales | Zheng et al. (2010) | . | ICNB |
| Mamiella | Mamiellales | Moestrup (2000); Marin & Melkonian (2010) | . | ICBN |
| Mamillariella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Mammea | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Mammelomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Mammillaria | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Mammilloydia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Manacus | Passeriformes | Clements (2007) | . | ICZN |
| Manania | Stauromedusae | Larson & Fautin (1989) | . | ICZN |
| Manaosella | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Manastirlia | Haemospororida | Perkins et al. (2000); Özdikmen (2009) | Substitute name for Rayella. | ICZN |
| Manchomonas | Apusomonadida | Cavalier-Smith & Chao (2010) | . | ICZN |
| Manchudinium | Phytodiniales | Fensome et al. (1993) | . | ICBN |
| Mancoa | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Mandenovia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mandevilla | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mandingoa | Passeriformes | Clements (2007) | . | ICZN |
| Mandoniella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Mandragora | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Mandrillus | Primates | Groves (2005) | . | ICZN |
| Manekia | Piperales | Mabberley (2008) | Piperaceae. | ICBN |
| Manettia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mangenotia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mangifera | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Mangonia | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Mangrovibacter | Enterobacteriales | Ramenshkumar et al. (2010) | . | ICNB |
| Mangroviflexus | Bacteroidales | Zhao et al. (2012) | . | ICNB |
| Manicaria | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Manicina | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Manihinea | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Theonellidae. | ICZN |
| Manihot | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Manilkara | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Maniltoa | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Manis | Pholidota | McKenna & Bell (1997) | . | ICZN |
| Mankyua | Ophioglossales | Christenhusz et al. (2011) | . | ICBN |
| Mannagettaea | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Mannheimia | Pasteurellales | Garrity et al. (2005) | . | ICNB |
| Mannia | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Manniella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Manniophyton | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Mannophryne | Anura | Vitt & Caldwell (2009) | Aromobatidae. | ICZN |
| Manoao | Araucariales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Manochlamys | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Manolepis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Manorina | Passeriformes | Clements (2007) | . | ICZN |
| Manostachya | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Manotes | Oxalidales | Mabberley (2008) | Connaraceae. | ICBN |
| Manouria | Testudinata | Vitt & Caldwell (2009) | Testudinidae. | ICZN |
| Mansariella | Limnomedusae | Bouillon et al. (2006) | . | ICZN |
| Mansoa | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Mansonia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Manta | Myliobatiformes | Nelson (2006) | . | ICZN |
| Mantalania | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mantamonas | Mantamonadida | Glücksman et al. (2011) | . | ICZN |
| Mantella | Anura | Vitt & Caldwell (2009) | Mantellidae. | ICZN |
| Mantellum | Synechococcales | Hoffmann et al. (2005) | . | ICBN |
| Mantheyus | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Mantidactylus | Anura | Vitt & Caldwell (2009) | Mantellidae. | ICZN |
| Mantisalca | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mantisia | Zingiberales | Mabberley (2008) | Zingiberaceae. | ICBN |
| Mantonella | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Mantoniella | Mamiellales | Moestrup (2000); Marin & Melkonian (2010) | . | ICBN |
| Mantonipatus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Mantophryne | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Mantoscyphidia | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Manucodia | Passeriformes | Clements (2007) | . | ICZN |
| Manuelophrya | Exogenida | Lynn (2008) | . | ICZN |
| Manulea | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Manuleopsis | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Mapania | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Mapaniopsis | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Mappia | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Mappianthus | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Maprounea | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Maquira | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Maractis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Marah | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Marahuacaea | Poales | Mabberley (2008) | Rapateaceae. | ICBN |
| Maraniona | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Maranta | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Maranthes | Malpighiales | Mabberley (2008) | Chrysobalanaceae. | ICBN |
| Marantochloa | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Marasmodes | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Marasphaerium | Chlorellales | Krienitz et al. (2012) | As Chlorellaceae. | ICBN |
| Marathrum | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Marattia | Marattiales | Christenhusz et al. (2011) | . | ICBN |
| Marcania | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Marcelliopsis | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Marcetia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Marcgravia | Ericales | Mabberley (2008) | Marcgraviaceae. | ICBN |
| Marcgraviastrum | Ericales | Mabberley (2008) | Marcgraviaceae. | ICBN |
| Marchantia | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Marchesinia | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Marcusiola | Acoela | Dörjes (1968) | . | ICZN |
| Maresearsia | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Maresia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Mareya | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Mareyopsis | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Margalefia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Margaretamys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Margaretta | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Margaritaria | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Margaritolobium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Margaritopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Margaroperdix | Galliformes | Clements (2007) | . | ICZN |
| Margarops | Passeriformes | Clements (2007) | . | ICZN |
| Margarornis | Passeriformes | Clements (2007) | . | ICZN |
| Margelliantha | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Margelopsis | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Marginisporum | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Marginopora | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Soritidae. | ICZN |
| Marginotricha | Euplotida | Lynn (2008) | . | ICZN |
| Marginulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Marginulinopsis | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Margotia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Margyricarpus | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Marianactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Maribacter | Flavobacteriales | Nedashkovskaya et al. (2004) | . | ICNB |
| Maribaculum | | Williams et al. (2007); Lai et al. (2009); Lee et al. (2011) | Later synonym of Henriciella. | ICNB |
| Maribius | Rhodobacterales | Choi et al. (2007) | . | ICNB |
| Maricaulis | | Garrity et al. (2005); Williams et al. (2007) | Domain Bacteria - Phylum Proteobacteria - Class Alphaproteobacteria. Hyphomonadaceae. | ICNB |
| Marichromatium | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Maricurvus | Alteromonadales | Iwaki et al. (2012) | . | ICNB |
| Marihabitans | Micrococcales | Kageyama et al. (2008); Ludwig et al. (2012) | . | ICNB |
| Marila | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Marina | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Marinactinospora | Streptosporangiales | Tian et al. (2009); Ludwig et al. (2012) | . | ICNB |
| Marinamoeba | Schizopyrenida | De Jonckheere et al. (2009) | . | ICZN |
| Marinecta | Endogenida | Lynn (2008) | . | ICZN |
| Marinellina | Macrodasyida | Balsamo et al. (2009) | . | ICZN |
| Marinibacillus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Marinicella | | Romanenko et al. (2010) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria. | ICNB |
| Marinichlorella | Chlorellales | Aslam et al. (2007) | Parachlorella clade in Chlorellaceae. | ICBN |
| Marinifilum | | Na et al. (2009) | Domain Bacteria - Phylum Bacteroidetes. | ICNB |
| Mariniflexile | Flavobacteriales | Nedashkovskaya et al. (2006) | . | ICNB |
| Marinilabilia | Bacteroidales | Garrity et al. (2005) | . | ICNB |
| Marinilactibacillus | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Marinimicrobium | Alteromonadales | Lim et al. (2006) | . | ICNB |
| Marininema | Bacillales | Li et al. (2012) | . | ICNB |
| Marinithermus | Thermales | Garrity et al. (2005) | . | ICNB |
| Marinitoga | Thermotogales | Garrity et al. (2005) | . | ICNB |
| Marinobacter | Alteromonadales | Garrity et al. (2005) | . | ICNB |
| Marinobacterium | Oceanospirillales | Garrity et al. (2005); Kim et al. (2007) | . | ICNB |
| Marinococcus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Marinomonas | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Marinoscillum | Sphingobacteriales | Seo et al. (2009) | . | ICNB |
| Marinospirillum | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Marinovum | Rhodobacterales | Martens et al. (2006) | . | ICNB |
| Marionella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Maripa | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Maripelta | Rhodymeniales | Schneider & Wynne (2007) | . | ICBN |
| Mariprofundus | | Emerson et al. (2010) | Domain Bacteria - Phylum Proteobacteria. This genus belongs to invalid class "Zetaproteobacteria" and order "Mariprofundales". | ICNB |
| Marisediminicola | Micrococcales | Li et al. (2010); Ludwig et al. (2012) | Microbacteriaceae. | ICNB |
| Marispirillum | Rhodospirillales | Lai et al. (2009) | . | ICNB |
| Maristentor | Heterotrichida | Lynn (2008) | . | ICZN |
| Maritalea | Rhizobiales | Hwang et al. (2009) | . | ICNB |
| Maritimibacter | Rhodobacterales | Lee et al. (2007) | . | ICNB |
| Maritimimonas | Flavobacteriales | Park et al. (2009) | . | ICNB |
| Marituja | Peniculida | Lynn (2008) | . | ICZN |
| Marivirga | Cytophagales | Nedashkovskaya et al. (2010); Ludwig et al. (2011) | . | ICNB |
| Marivita | Rhodobacterales | Hwang et al. (2009) | . | ICNB |
| Marixanthomonas | Flavobacteriales | Romanenko et al. (2007) | . | ICNB |
| Markea | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Markhamia | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Marlierea | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Marlothiella | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Marlothistella | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Marmaronetta | Anseriformes | Clements (2007) | . | ICZN |
| Marmaroxylon | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Marmoricola | Propionibacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Marmoritis | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Marmorosphax | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Marmosa | Ameridelphia | McKenna & Bell (1997) | . | ICZN |
| Marmosops | Didelphimorphia | Gardner (2005) | . | ICZN |
| Marmota | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Marojejya | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Marophrys | Acanthocystida | Cavalier-Smith & von der Heyden (2007); Yabuki et al. (2012) | Marophryidae. | ICZN |
| Marquesia | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Marrubium | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Marrus | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Marsdenia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Marshallia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Marshalljohnstonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Marsilea | Salviniales | Christenhusz et al. (2011) | . | ICBN |
| Marsipella | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rhabdamminidae. | ICZN |
| Marsippospermum | Poales | Mabberley (2008) | Juncaceae. | ICBN |
| Marssoniella | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Marsupella | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Marsupidium | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Marsupiomonas | Pedinomonadales | Jones et al. (1994); Moestrup (2000) | . | ICBN |
| Marsupulina | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Marsupulinoides | Astrorhizida | Kaminski (2000) | Saccammininae. | ICZN |
| Marsypianthes | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Marsypopetalum | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Marteilia | Paramyxida | Bass et al. (2009) | . | ICZN |
| Martelella | Rhizobiales | Rivas et al. (2005) | . | ICNB |
| Martellidendron | Pandanales | Mabberley (2008) | Pandanaceae. | ICBN |
| Martensia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Martes | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Marthella | Dioscoreales | Mabberley (2008) | Burmanniaceae. | ICBN |
| Marticorenia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Martinella | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Martinottiella | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Eggerellidae. | ICZN |
| Martiodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Martretia | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Martynia | Lamiales | Mabberley (2008) | Martyniaceae. | ICBN |
| Marvania | Chlorellales | Somogyi et al. (2011); Neustupa et al. (2011) | As Nannochloris-like clade. | ICBN |
| Marvinbryantia | Clostridiales | Wolin et al. (2008) | Replacement name of Bryantella. | ICNB |
| Maryna | Colpodida | Lynn (2008) | . | ICZN |
| Masaia | Chlorellales | Krienitz et al. (2012) | As Chlorellaceae. | ICBN |
| Masakiella | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Mascarenhasia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Maschalocephalus | Poales | Mabberley (2008) | Rapateaceae. | ICBN |
| Maschalodesme | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Masdevallia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Masius | Passeriformes | Clements (2007) | . | ICZN |
| Masoala | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Masonella | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hemisphaeramminidae. | ICZN |
| Massilia | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Massilina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Massilinoides | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Massisteria | Leucodictyida | Cavalier-Smith & Chao (2003); Howe et al. (2011) | . | ICZN |
| Massonia | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Massoutiera | Rodentia | McKenna & Bell (1997); Dieterlen (2005) | Misspelled as Massouteria in McKenna & Bell (1997). | ICZN |
| Massularia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mastacomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Mastersia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mastersiella | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Masticophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Mastigamoeba | Mastigamoebida | Brugerolle & Patterson (2000); Cavalier-Smith et al. (2004) | . | ICZN |
| Mastigella | Mastigamoebida | Brugerolle & Patterson (2000); Cavalier-Smith et al. (2004) | . | ICZN |
| Mastigias | Rhizostomeae | Kramp (1961) | . | ICZN |
| Mastigietta | Rhizostomeae | Kramp (1961) | . | ICZN |
| Mastigina | Pelobiontida | Brugerolle & Patterson (2000); Cavalier-Smith et al. (2004) | . | ICZN |
| Mastigocladopsis | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Mastigocladus | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Mastigocoleopsis | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Mastigocoleus | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Mastigodryas | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Mastigolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Mastigopelma | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Mastigophora | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Mastigosciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mastigostyla | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Mastixia | Cornales | Mabberley (2008) | Nyssaceae. | ICBN |
| Mastixiodendron | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mastocarpus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Mastocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Mastomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Mastophora | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Mastophoropsis | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Mastopoma | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Masudaphycus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Matanzioides | Lituolida | Kaminski (2008) | Liebusellinae. | ICZN |
| Matayba | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Mataza | | Yabuki & Ishida (2011) | Domain Eucarya - Phylum Cercozoa - Class Thecofilosea. | ICZN |
| Matelea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mathewsia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Mathiasella | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mathurina | Malpighiales | Mabberley (2008) | Passifloraceae. | ICBN |
| Maticora | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Matisia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Matoatoa | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Matonia | Gleicheniales | Christenhusz et al. (2011) | . | ICBN |
| Matricaria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Matsakision | Euglyphida | Meisterfeld (2000) | . | ICZN |
| Matsumurella | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Matteia | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Matteria | Orthotrichales | Goffinet et al. (2009) | . | ICBN |
| Mattesia | Neogregarinorida | Perkins et al. (2000) | . | ICZN |
| Mattfeldanthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mattfeldia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Matthaea | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Matthiola | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Matucana | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Matudaea | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Matudanthus | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Maudammina | Psamminida | Gooday & Tendal (2000) | . | ICZN |
| Maullinia | Plasmodiophorida | Kirk et al. (2008) | . | ICZN |
| Mauloutchia | Magnoliales | Mabberley (2008) | Myristicaceae. | ICBN |
| Maundia | Alismatales | Mabberley (2008) | Juncaginaceae. | ICBN |
| Maupasella | Astomatida | Lynn (2008) | . | ICZN |
| Maurandella | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Maurandya | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Mauremys | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Mauria | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Mauritia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Mauritiella | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Maurocenia | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Maxburretia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Maxillaria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Maxomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Maxonia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Maxwellia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Mayaca | Poales | Mabberley (2008) | Mayacaceae. | ICBN |
| Mayermys | Rodentia | McKenna & Bell (1997); Musser & Carleton (2005) | Later synonym of Pseudohydromys. | ICZN |
| Mayna | Malpighiales | Mabberley (2008) | Achariaceae. | ICBN |
| Mayorella | Dermamoebida | Rogerson & Patterson (2000); Smirnov et al. (2005); Smirnov et al. (2011) | . | ICZN |
| Mayrornis | Passeriformes | Clements (2007) | . | ICZN |
| Maytenus | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Mazaea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mazama | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Mazoyerella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Mazus | Lamiales | Mabberley (2008) | Phrymaceae. | ICBN |
| Mazzaella | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Mcvaughia | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Meandrina | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Meandrospira | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Cornuspiridae. | ICZN |
| Meara | Nemertodermatida | Sterrer (1998) | . | ICZN |
| Mearnsia | Apodiformes | Clements (2007) | . | ICZN |
| Meator | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Mecardonia | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Mechercharimyces | Bacillales | Matsuo et al. (2006) | . | ICNB |
| Mechowia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Mecistophora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Mecistops | Crocodylia | Vitt & Caldwell (2009) | Crocodylidae. | ICZN |
| Mecocerculus | Passeriformes | Clements (2007) | . | ICZN |
| Mecomischus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Meconella | Ranunculales | Mabberley (2008) | Papaveraceae. | ICBN |
| Meconopsis | Ranunculales | Mabberley (2008) | Papaveraceae. | ICBN |
| Mecopus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mecranium | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Mecynostomum | Acoela | Dörjes (1968); Faubel & Noreña (2001) | . | ICZN |
| Medeiothamnion | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Medemia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Medeola | Liliales | Mabberley (2008) | Liliaceae. | ICBN |
| Mediasia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Medicago | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Medicosma | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Medinilla | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Mediocalcar | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mediorhynchus | Gigantorhynchida | Amin (1985) | . | ICZN |
| Mediusella | Malvales | Mabberley (2008) | Sarcolaenaceae. | ICBN |
| Medusagyne | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Medusandra | Saxifragales | Mabberley (2008) | Medusandraceae. | ICBN |
| Medusanthera | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Medusetta | Phaeogromida | Takahashi & Anderson (2000) | . | ICZN |
| Medusoides | Pythiales | Dick (2001); Kirk et al. (2008) | Pythiogetonaceae. | ICBN |
| Meeboldia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Meeboldina | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Meehania | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Meesia | Splachnales | Goffinet et al. (2009) | . | ICBN |
| Megabyas | Passeriformes | Clements (2007) | . | ICZN |
| Megacarpaea | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Megaceros | Dendrocerotales | Renzaglia et al. (2009) | . | ICBN |
| Megaceryle | Coraciiformes | Clements (2007) | . | ICZN |
| Megachasma | Lamniformes | Nelson (2006) | . | ICZN |
| Megaciella | Poecilosclerida | Hooper (2002) | . | ICZN |
| Megacodon | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Megacorax | Myrtales | Mabberley (2008) | Onagraceae. | ICBN |
| Megacrex | Gruiformes | Clements (2007) | . | ICZN |
| Megadasys | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Megadendromus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Megadenia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Megaderma | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Megadinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Megadontomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Megadyptes | Sphenisciformes | Clements (2007) | . | ICZN |
| Megaelosia | Anura | Vitt & Caldwell (2009) | Hylodidae. | ICZN |
| Megaerops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Megahertzia | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Megalachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Megalactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Megalaima | Piciformes | Clements (2007) | . | ICZN |
| Megalastrum | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Megaleia | Australidelphia | McKenna & Bell (1997); Groves (2005) | Later synonym of Macropus. | ICZN |
| Megalembidium | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Megaleranthis | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Megalocercus | Appendicularia | Fenaux (1998) | . | ICZN |
| Megalochlamys | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Megalodicopia | Phlebobranchia | Monniot & Monniot (1972) | Octacnemidae. | ICZN |
| Megaloglossus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Megalomys | Rodentia | Musser & Carleton (2005) | Recently extinct. | ICZN |
| Megaloprotachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Megalorchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Megalostoma | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Megalotus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Megalurulus | Passeriformes | Clements (2007) | . | ICZN |
| Megalurus | Passeriformes | Clements (2007) | . | ICZN |
| Megamonas | Selenomonadales | Garrity et al. (2005); Morotomi et al. (2007); Marchandin et al. (2010) | . | ICNB |
| Meganema | Rhizobiales | Thomsen et al. (2006) | . | ICNB |
| Megaoryzomys | Rodentia | Musser & Carleton (2005) | Recently extinct. | ICZN |
| Megaphrynium | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Megapodius | Galliformes | Clements (2007) | . | ICZN |
| Megapogon | Leucosolenida | Borojevic et al. (2002) | . | ICZN |
| Megapriapus | Echinorhynchida | Amin (1985) | . | ICZN |
| Megaptera | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Megarynchus | Passeriformes | Clements (2007) | . | ICZN |
| Megascops | Strigiformes | Clements (2007) | . | ICZN |
| Megaskepasma | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Megasorex | Soricomorpha | Hutterer (2005) | . | ICZN |
| Megasphaera | Selenomonadales | Garrity et al. (2005); Marchandin et al. (2010) | . | ICNB |
| Megastachya | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Megastictus | Passeriformes | Clements (2007) | . | ICZN |
| Megastigma | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Megastomatohyla | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Megastygarctides | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Megastylis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Megatriorchis | Falconiformes | Clements (2007) | . | ICZN |
| Megatritheca | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Megavestibulum | Macropodiniida | Lynn (2008) | . | ICZN |
| Megaxenops | Passeriformes | Clements (2007) | . | ICZN |
| Megazosterops | Passeriformes | Clements (2007) | . | ICZN |
| Megistacantha | Echinorhynchida | Amin (1985) | . | ICZN |
| Megistostegium | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Megistostigma | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Meglitschia | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Megophrys | Anura | Vitt & Caldwell (2009) | Megophryidae. | ICZN |
| Mehelya | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Meidamonella | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Eggerellidae. | ICZN |
| Meiglyptes | Piciformes | Clements (2007) | . | ICZN |
| Meineckia | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Meiocarpidium | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Meiodiscus | Palmariales | Schneider & Wynne (2007) | . | ICBN |
| Meioglossus | Helminthomorpha | Worsaae et al. (2012) | . | ICZN |
| Meiogyne | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Meionemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Meiopriapulus | Meiopriapulomorpha | Adrianov & Malakhov (1996) | . | ICZN |
| Meiostemon | Myrtales | Mabberley (2008) | Combretaceae. | ICBN |
| Meiostoma | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Meiotheciella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Meiothecium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Meiothermus | Thermales | Garrity et al. (2005) | . | ICNB |
| Meiotrichum | Polytrichales | Goffinet et al. (2009) | . | ICBN |
| Meiracyllium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Meizodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Meizotropis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Meladerma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Melaenornis | Passeriformes | Clements (2007) | . | ICZN |
| Melaleuca | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Melampitta | Passeriformes | Clements (2007) | . | ICZN |
| Melampodium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Melamprosops | Passeriformes | Clements (2007) | . | ICZN |
| Melampyrum | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Melananthus | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Melancium | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Melanema | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Melanerpes | Piciformes | Clements (2007) | . | ICZN |
| Melaniparus | Passeriformes | Clements (2007) | . | ICZN |
| Melanitta | Anseriformes | Clements (2007) | . | ICZN |
| Melanobatrachus | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Melanocenchris | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Melanocharis | Passeriformes | Clements (2007) | . | ICZN |
| Melanochelys | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Melanochlora | Passeriformes | Clements (2007) | . | ICZN |
| Melanochyla | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Melanocorypha | Passeriformes | Clements (2007) | . | ICZN |
| Melanodendron | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Melanodera | Passeriformes | Clements (2007) | . | ICZN |
| Melanodinium | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae - Subclass Peridiniphycidae. | ICBN |
| Melanodryas | Passeriformes | Clements (2007) | . | ICZN |
| Melanolepis | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Melanomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Melanopareia | Passeriformes | Clements (2007) | . | ICZN |
| Melanoperdix | Galliformes | Clements (2007) | . | ICZN |
| Melanophidium | Squamata | Vitt & Caldwell (2009) | Serpentes. Uropeltidae. | ICZN |
| Melanophryniscus | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Melanophylla | Apiales | Mabberley (2008) | Torricelliaceae. | ICBN |
| Melanopsidium | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Melanoptila | Passeriformes | Clements (2007) | . | ICZN |
| Melanortocarya | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Melanosciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Melanoselinum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Melanoseps | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Melanospermum | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Melanospiza | Passeriformes | Clements (2007) | . | ICZN |
| Melanostachya | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Melanosuchus | Crocodylia | Vitt & Caldwell (2009) | Alligatoridae. | ICZN |
| Melanothamnus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Melanotis | Passeriformes | Clements (2007) | . | ICZN |
| Melanoxylum | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Melanthalia | Gracilariales | Schneider & Wynne (2007) | . | ICBN |
| Melanthera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Melanthium | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Melasma | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Melasmothrix | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Melasphaerula | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Melastoma | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Melastomastrum | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Meleagris | Galliformes | Clements (2007) | . | ICZN |
| Meles | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Melghirimyces | Bacillales | Addou et al. (2012) | . | ICNB |
| Melhania | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Melia | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Melianthus | Geraniales | Mabberley (2008) | Melianthaceae. | ICBN |
| Melica | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Melicertissa | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Melicertoides | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Melicertum | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Melichneutes | Piciformes | Clements (2007) | . | ICZN |
| Melichrus | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Melicoccus | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Melicope | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Melicytus | Malpighiales | Mabberley (2008) | Violaceae. | ICBN |
| Melidectes | Passeriformes | Clements (2007) | . | ICZN |
| Melidora | Coraciiformes | Clements (2007) | . | ICZN |
| Melientha | Santalales | Mabberley (2008) | Opiliaceae. | ICBN |
| Melierax | Falconiformes | Clements (2007) | . | ICZN |
| Melignomon | Piciformes | Clements (2007) | . | ICZN |
| Melilestes | Passeriformes | Clements (2007) | . | ICZN |
| Melilotus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Melinia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Melinis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Meliosma | Sabiales | Mabberley (2008) | Sabiaceae. | ICBN |
| Meliphaga | Passeriformes | Clements (2007) | . | ICZN |
| Melipotes | Passeriformes | Clements (2007) | . | ICZN |
| Melissa | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Melissococcus | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Melitea | | Urios et al. (2008); Jang et al. (2011) | Later synonym of Spongiibacter. | ICNB |
| Melithaea | Alcyonacea | Bayer (1981) | Melithaeidae. | ICZN |
| Melithreptus | Passeriformes | Clements (2007) | . | ICZN |
| Melitograis | Passeriformes | Clements (2007) | . | ICZN |
| Melittacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Melittangium | Myxococcales | Garrity et al. (2005) | . | ICNB |
| Melittis | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Mellera | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Melliniella | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Melliodendron | Ericales | Mabberley (2008) | Styracaceae. | ICBN |
| Mellisuga | Apodiformes | Clements (2007) | . | ICZN |
| Mellivora | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Mellonympha | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Melobesia | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Melocactus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Melocalamus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Melocanna | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Melocarpum | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Melochia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Melocichla | Passeriformes | Clements (2007) | . | ICZN |
| Melodinus | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Melodorum | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Melogale | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Melolobium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Melomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Melonanchora | Poecilosclerida | Van Soest (2002) | . | ICZN |
| Melonis | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nonionidae. | ICZN |
| Melonycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Melophlus | Astrophorida | Uriz (2002) | . | ICZN |
| Melophus | Passeriformes | Clements (2007) | . | ICZN |
| Melophysa | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Melopsittacus | Psittaciformes | Clements (2007) | . | ICZN |
| Melopyrrha | Passeriformes | Clements (2007) | . | ICZN |
| Melosperma | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Melospiza | Passeriformes | Clements (2007) | . | ICZN |
| Melothria | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Melothrianthus | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Melozone | Passeriformes | Clements (2007) | . | ICZN |
| Melpomene | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Melursus | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Membranella | Erythropeltidales | Schneider & Wynne (2007); | . | ICBN |
| Membranicola | Tintinnida | Lynn (2008) | . | ICZN |
| Membranoptera | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Membranosporus | Plasmodiophorida | Kirk et al. (2008) | . | ICZN |
| Memecylon | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Mena | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Menais | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Mendoncia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Mendoravia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Menella | Alcyonacea | Bayer (1981) | Plexauridae. | ICZN |
| Menepetalum | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Menetes | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Menetia | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Meniscogyne | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Meniscus | Cytophagales | Garrity et al. (2005); Ludwig et al. (2011) | . | ICNB |
| Menispermum | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Menkea | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Menoidium | Rhabdomonadales | Leedale (1967); Leedale (2000) | . | ICBN |
| Menonvillea | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Menospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Mentha | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Mentzelia | Cornales | Mabberley (2008) | Loasaceae. | ICBN |
| Menura | Passeriformes | Clements (2007) | . | ICZN |
| Menyanthes | Asterales | Mabberley (2008) | Menyanthaceae. | ICBN |
| Menzbieria | Neogregarinorida | Perkins et al. (2000) | . | ICZN |
| Mephitis | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Merciera | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Mercurialis | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Meredithia | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Merga | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Merganetta | Anseriformes | Clements (2007) | . | ICZN |
| Mergellus | Anseriformes | Clements (2007) | . | ICZN |
| Mergonemertes | Pelagica | Gibson (1995) | . | ICZN |
| Mergus | Anseriformes | Clements (2007) | . | ICZN |
| Meriandra | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Meriania | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Merianthera | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Mericarpaea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Meriderma | Stemonitales | Poulain et al. (2011) | . | ICBN |
| Meridianimaribacter | Flavobacteriales | Wang et al. (2010) | . | ICNB |
| Meridiocolax | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Meringosphaera | | Ettl (1978); Silva (1979) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. Possibly Xanthophyceae or Chrysophyceae. | ICBN |
| Merinthopodium | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Meriones | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Merismogloea | Mischococcales | Ettl (1978) | . | ICBN |
| Merismopedia | Synechococcales | Hoffmann et al. (2005) | . | ICBN |
| Meristiella | Gigartinales | Schneider & Wynne (2007) | Later synonym of Meristotheca. | ICBN |
| Meristocarpus | Stolidobranchia | Monniot & Monniot (1972); Kott (1998) | Junior synonym of Molgula. | ICZN |
| Meristogenys | Anura | Vitt & Caldwell (2009) | Ranidae. | ICZN |
| Meristotheca | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Merlia | Poecilosclerida | Hajdu & Van Soest (2002) | . | ICZN |
| Merocinta | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Merocystis | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Merodinium | Syndinida | Fensome et al. (1993) | . | ICZN |
| Merogregarina | Archigregarinorida | Perkins et al. (2000) | . | ICZN |
| Meroles | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Merona | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Merope | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Meropogon | Coraciiformes | Clements (2007) | . | ICZN |
| Merops | Coraciiformes | Clements (2007) | . | ICZN |
| Meroselenidium | Archigregarinorida | Perkins et al. (2000) | . | ICZN |
| Merostachys | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Merotricha | Raphidomonadales | Heywood & Leedale (2000) | . | ICBN |
| Merremia | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Merrillanthus | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Merrillia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Merrilliobryum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Merrilliodendron | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Merrilliopanax | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Merrittia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mertensia | Cydippida | Harbison & Madin (1982) | . | ICZN |
| Mertensia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Mertensiella | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Mertensophryne | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Merulaxis | Passeriformes | Clements (2007) | . | ICZN |
| Merulina | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Merumea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Merwilla | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Merxmuellera | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Meryta | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Mesacmaea | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Mesactinia | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Mesadenella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mesadenus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mesalina | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Mesanophrys | Philasterida | Lynn (2008) | . | ICZN |
| Mesanthemum | Poales | Mabberley (2008) | Eriocaulaceae. | ICBN |
| Mesanthophora | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mesaspis | Squamata | Vitt & Caldwell (2009) | Anguidae. | ICZN |
| Mesechinus | Erinaceomorpha | Hutterer (2005) | . | ICZN |
| Mesechites | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mesembrinibis | Ciconiiformes | Clements (2007) | . | ICZN |
| Mesembriomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Mesembryanthemum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Meseres | Sporadotrichida | Lynn (2008) | . | ICZN |
| Mesitornis | Gruiformes | Clements (2007) | . | ICZN |
| Mesnilella | Astomatida | Lynn (2008) | . | ICZN |
| Mesnilium | Haemospororida | Perkins et al. (2000) | . | ICZN |
| Mesobaena | Squamata | Vitt & Caldwell (2009) | Amphisbaenidae. | ICZN |
| Mesocapromys | Rodentia | Woods & Kilpatrick (2005) | . | ICZN |
| Mesoceros | Notothyladales | Renzaglia et al. (2009) | . | ICBN |
| Mesochaete | Aulacomniales | Stech & Frey (2008); Goffinet et al. (2009) | . | ICBN |
| Mesochordaeus | Appendicularia | Fenaux (1998) | . | ICZN |
| Mesocricetus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Mesocrista | Parachela | Kinchin (1994) | . | ICZN |
| Mesodasys | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Mesodinium | Cyclotrichiida | Lynn (2008) | . | ICZN |
| Mesofila | Cryptofilida | Bass et al. (2009) | . | ICZN |
| Mesoflavibacter | Flavobacteriales | Asker et al. (2007) | . | ICNB |
| Mesoglossus | Helminthomorpha | Deland et al. (2010) | Harrimaniidae. | ICZN |
| Mesognatharia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Mesogramma | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mesogymnus | Pleuronematida | Lynn (2008) | Nomen nudum. | ICZN |
| Mesogyne | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Mesoikopleura | Appendicularia | Fenaux (1998) | . | ICZN |
| Mesolembus | Philasterida | Lynn (2008) | . | ICZN |
| Mesolenticulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Mesomelaena | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Mesomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Mesonia | Flavobacteriales | Nedashkovskaya et al. (2003) | . | ICNB |
| Mesonodon | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Mesopatellina | Spirillinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Patellinidae. | ICZN |
| Mesopateoris | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Mesopedinella | Pedinellales | Sekiguchi et al. (2003) | . | ICBN |
| Mesoperipatus | Euonychophora | Peck (1975) | Peripatidae. | ICZN |
| Mesophilobacter | Pseudomonadales | Garrity et al. (2005) | . | ICNB |
| Mesophylla | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mesophyllum | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Mesoplasma | Entomoplasmatales | Garrity et al. (2005) | . | ICNB |
| Mesoplodon | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Mesoporos | Prorocentrales | Dodge & Lee (2000) | . | ICBN |
| Mesoporos | Prorocentrales | Fensome et al. (1993); Greuter (1993) | Not "Mosoporus". | ICBN |
| Mesoptychia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Mesorhizobium | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Mesosagitta | Aphragmophora | Bieri (1991) | Sagittidae. | ICZN |
| Mesoscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Mesosetum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mesosigmoilina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Mesospinidium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mesostigma | Mesostigmatales | Marin & Melkonian (1999) | . | ICBN |
| Mesostygarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Mesotaenium | Zygnematales | Gontcharov (2008) | . | ICBN |
| Mesothamnium | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Mesotriton | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Mesotus | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Mespilus | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Messemvriella | Euglyphida | Meisterfeld (2000) | . | ICZN |
| Mestoklema | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Mesua | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Metabakuella | Urostylida | Lynn (2008) | . | ICZN |
| Metabolos | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Metabolus | Passeriformes | Clements (2007) | . | ICZN |
| Metabriggsia | Lamiales | Mabberley (2008); Weber et al. (2011) | Gesneriaceae. Later synonym of Hemiboea. | ICBN |
| Metacalypogeia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Metacanthocephaloides | Echinorhynchida | Amin (1985) | . | ICZN |
| Metacanthocephalus | Echinorhynchida | Amin (1985) | . | ICZN |
| Metachaos | Euamoebida | Rogerson & Patterson (2000); Smirnov et al. (2005); Smirnov et al. (2011) | Amoebidae. | ICZN |
| Metachirus | Ameridelphia | McKenna & Bell (1997) | . | ICZN |
| Metacineta | Exogenida | Lynn (2008) | . | ICZN |
| Metaclevelandella | Clevelandellida | Lynn (2008) | . | ICZN |
| Metacollinia | | Lynn (2008) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Ciliophora - Subphylum Intramacronucleata. Vestibuliferida or Apostomatida. | ICZN |
| Metacoronympha | Cristamonadida | Cepicka et al. (2010) | . | ICZN |
| Metacrinia | Anura | Vitt & Caldwell (2009) | Myobatrachidae. | ICZN |
| Metacylis | Tintinnida | Lynn (2008) | . | ICZN |
| Metacystis | Prostomatida | Lynn (2008) | . | ICZN |
| Metadevescovina | Cristamonadida | Cepicka et al. (2010) | . | ICZN |
| Metadina | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Metadinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Metadinophysis | Dinophysiales | Fensome et al. (1993) | . | ICBN |
| Metadistichophyllum | Hookeriales | Goffinet et al. (2009) | . | ICBN |
| Metafolliculina | Heterotrichida | Lynn (2008) | . | ICZN |
| Metagentiana | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Metagoniolithon | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Metahygrobiella | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Metalasia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Metalcyonium | Alcyonacea | Bayer (1981) | Alcyoniidae. | ICZN |
| Metalejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Metalingulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glandulinidae. | ICZN |
| Metallogorgia | Alcyonacea | Bayer (1981) | Chrysogorgiidae. | ICZN |
| Metallosphaera | Sulfolobales | Garrity et al. (2005) | . | ICNB |
| Metallura | Apodiformes | Clements (2007) | . | ICZN |
| Metamastophora | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Metamera | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Metamorphe | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Metandrocarpa | Stolidobranchia | Monniot & Monniot (1972) | Styelidae. | ICZN |
| Metaneckera | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Metanema | Sphenomonadales | Leedale (2000); Özdikmen (2009) | Junior homonym. Substituted by Semihia. | ICBN |
| Metanemone | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Metania | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Metanophrys | Philasterida | Lynn (2008) | . | ICZN |
| Metanyctotherus | Clevelandellida | Lynn (2008) | . | ICZN |
| Metapanax | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Metapatellina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ungulatellidae. | ICZN |
| Metapeachia | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Metaperipatus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Metapetrocosmea | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Metapeyssonnelia | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Metaphalacroma | Dinophysiales | Fensome et al. (1993) | . | ICBN |
| Metaphrya | Apostomatida | Lynn (2008) | . | ICZN |
| Metaphrynella | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Metaphryniscus | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Metaplexis | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Metapolymorphina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Polymorphinidae. | ICZN |
| Metaporana | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Metaptychostomum | Thigmotrichida | Lynn (2008) | . | ICZN |
| Metaracoelophrya | Astomatida | Lynn (2008) | . | ICZN |
| Metaradiophrya | Astomatida | Lynn (2008) | . | ICZN |
| Metarhadinorhynchus | Echinorhynchida | Amin (1985) | . | ICZN |
| Metarhodactis | Corallimorpharia | Fautin et al. (2007) | . | ICZN |
| Metarotaliella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rotaliellidae. | ICZN |
| Metarungia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Metascardovia | Bifidobacteriales | Okamoto et al. (2007); Ludwig et al. (2012) | . | ICNB |
| Metasequoia | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Metasicuophora | Clevelandellida | Lynn (2008) | . | ICZN |
| Metastachydium | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Metastomum | Astomatida | Lynn (2008) | . | ICZN |
| Metastrombidium | Strombidiida | Lynn (2008) | . | ICZN |
| Metastrongylidium | Stichotrichida | Xu & Lei (2007) | . | ICZN |
| Metatrichia | Trichiales | Yamamoto (1998) | . | ICBN |
| Metatrophis | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Metauroleptus | Stichotrichida | Foissner et al. (2008) | . | ICZN |
| Metaurostylopsis | Urostylida | Lynn (2008) | . | ICZN |
| Metaxya | Cyatheales | Christenhusz et al. (2011) | . | ICBN |
| Metcalfia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Metcalfina | Salpida | Godeaux (1998) | . | ICZN |
| Metchnikovella | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Metedwardsia | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Meteoridium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Meteoriella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Meteoriopsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Meteorium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Meteoromyrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Metephelota | Exogenida | Lynn (2008) | . | ICZN |
| Meterostachys | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Methanimicrococcus | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanobacterium | Methanobacteriales | Garrity et al. (2005) | . | ICNB |
| Methanobrevibacter | Methanobacteriales | Garrity et al. (2005) | . | ICNB |
| Methanocalculus | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanocaldococcus | Methanococcales | Garrity et al. (2005) | . | ICNB |
| Methanocella | Methanocellales | Sakai et al. (2008) | . | ICNB |
| Methanococcoides | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanococcus | Methanococcales | Garrity et al. (2005) | . | ICNB |
| Methanocorpusculum | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanoculleus | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanofollis | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanogenium | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanohalobium | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanohalophilus | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanolacinia | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanolinea | Methanomicrobiales | Imachi et al. (2008) | . | ICNB |
| Methanolobus | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanomassiliicoccus | | Dridi et al. (2012) | Domain Archaea - Kingdom Euryarchaeota - Phylum Euryarchaeota. Validly published by Validation List no. 148. | ICNB |
| Methanomethylovorans | Methanosarcinales | Lomans et al. (1999) | . | ICNB |
| Methanomicrobium | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanomicrococcus | Methanosarcinales | Garrity et al. (2005) | Incorrect spelling of Methanimicrococcus. | ICNB |
| Methanoplanus | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanopyrus | Methanopyrales | Garrity et al. (2005) | . | ICNB |
| Methanoregula | Methanomicrobiales | Bräuer et al. (2011); Yashiro et al. (2011) | . | ICNB |
| Methanosaeta | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanosalsum | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanosarcina | Methanosarcinales | Garrity et al. (2005) | . | ICNB |
| Methanosphaera | Methanobacteriales | Garrity et al. (2005) | . | ICNB |
| Methanosphaerula | Methanomicrobiales | Cadillo-Quiroz et al. (2009) | . | ICNB |
| Methanospirillum | Methanomicrobiales | Garrity et al. (2005) | . | ICNB |
| Methanothermobacter | Methanobacteriales | Garrity et al. (2005) | . | ICNB |
| Methanothermococcus | Methanococcales | Garrity et al. (2005) | . | ICNB |
| Methanothermus | Methanobacteriales | Garrity et al. (2005) | . | ICNB |
| Methanothrix | Methanosarcinales | Garrity et al. (2005) | Earlier synonym of Methanosaeta. Rejected in opinion 75.. | ICNB |
| Methanotorris | Methanococcales | Garrity et al. (2005) | . | ICNB |
| Metharme | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Methermicoccus | Methanosarcinales | Cheng et al. (2007) | . | ICNB |
| Methylarcula | Rhodobacterales | Garrity et al. (2005) | . | ICNB |
| Methylibium | Burkholderiales | Nakatsu et al. (2006) | . | ICNB |
| Methylobacillus | Methylophilales | Garrity et al. (2005) | . | ICNB |
| Methylobacter | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylobacterium | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methylocaldum | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylocapsa | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methylocella | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methylococcus | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylocystis | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methyloferula | Rhizobiales | Vorobev et al. (2011) | . | ICNB |
| Methylogaea | Methylococcales | Geymonat et al. (2011) | . | ICNB |
| Methylohalobius | Methylococcales | Heyer et al. (2005) | . | ICNB |
| Methylohalomonas | Chromatiales | Sorokin et al. (2007) | . | ICNB |
| Methylomicrobium | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylomonas | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylonatrum | Chromatiales | Sorokin et al. (2007) | . | ICNB |
| Methylophaga | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Methylophilus | Methylophilales | Garrity et al. (2005) | . | ICNB |
| Methylopila | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methylorhabdus | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methylorosula | Rhizobiales | Berestovskaya et al. (2012) | . | ICNB |
| Methylosarcina | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylosinus | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Methylosoma | Methylococcales | Rahalkar et al. (2007) | . | ICNB |
| Methylosphaera | Methylococcales | Garrity et al. (2005) | . | ICNB |
| Methylotenera | Methylophilales | Kalyuzhnaya et al. (2006) | . | ICNB |
| Methylothermus | Methylococcales | Tsubota et al. (2005) | . | ICNB |
| Methyloversatilis | Rhodocyclales | Kalyuzhnaya et al. (2006) | . | ICNB |
| Methylovirgula | Rhizobiales | Vorob'ev et al. (2009) | . | ICNB |
| Methylovorus | Methylophilales | Garrity et al. (2005) | . | ICNB |
| Methylovulum | Methylococcales | Iguchi et al. (2011) | . | ICNB |
| Metoikos | Philasterida | Lynn (2008) | Nomen nudum. | ICZN |
| Metopidius | Charadriiformes | Clements (2007) | . | ICZN |
| Metopion | Metopiida | Howe et al. (2009) | . | ICZN |
| Metopium | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Metopothrix | Passeriformes | Clements (2007) | . | ICZN |
| Metopus | Armophorida | Lynn (2008) | . | ICZN |
| Metoxypetalum | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Metridium | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Metriopelia | Columbiformes | Clements (2007) | . | ICZN |
| Metrodorea | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Metromonas | Metromonadida | Bass & Cavalier-Smith (2004) | . | ICZN |
| Metrosideros | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Metroxylon | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Metschnikowia | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Metteniusa | Metteniusales | Mabberley (2008) | Metteniusaceae. | ICBN |
| Metternichia | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Metzgeria | Metzgeriales | Crandall-Stotler et al. (2009) | . | ICBN |
| Meum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mexacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Mexerion | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mexianthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Meximalva | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Mexipedium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Meyenia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Meyerella | Chlorellales | Luo et al. (2009) | Chlorella clade in Chlorellaceae. | ICBN |
| Meyerophytum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Meyna | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mezia | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Meziella | Saxifragales | Mabberley (2008) | Haloragaceae. | ICBN |
| Mezilaurus | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Mezobromelia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Mezoneuron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mezzettia | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Miamiensis | Philasterida | Lynn (2008) | . | ICZN |
| Mibora | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Micaelamys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Micatuba | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Micavibrio | Bdellovibrionales | Garrity et al. (2005) | . | ICNB |
| Micconemertes | Heteronemertea | Kajihara et al. (2008) | . | ICZN |
| Michaelsarsia | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Syracosphaeraceae. | ICBN |
| Michauxia | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Michelsonia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Micholitzia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mickelia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Micklethwaitia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Miconia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Micoureus | Ameridelphia | McKenna & Bell (1997) | . | ICZN |
| Micrablepharus | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Micracanthodinium | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae. | ICBN |
| Micracanthorhynchina | Echinorhynchida | Amin (1985) | . | ICZN |
| Micractinium | Chlorellales | Luo et al. (2009) | Chlorella clade in Chlorellaceae. | ICBN |
| Micractis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Micraeschynanthus | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Micraira | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Micralsopsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Micramphora | Tectofilosida | Meisterfeld (2000); Cavalier-Smith & Chao (2003) | Psammonobiotidae. | ICZN |
| Micrandra | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Micrandropsis | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Micranthemum | Lamiales | Mabberley (2008) | Linderniaceae. | ICBN |
| Micrantheum | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Micranthocereus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Micranthus | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Micrargeria | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Micrargeriella | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Micrasepalum | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Micrasterias | Desmidiales | Gontcharov (2008) | . | ICBN |
| Micrastur | Falconiformes | Clements (2007) | . | ICZN |
| Micrathene | Strigiformes | Clements (2007) | . | ICZN |
| Micrelaps | Squamata | Vitt & Caldwell (2009) | Serpentes. Atractaspididae. | ICZN |
| Micrella | Heteronemertea | Gibson (1995) | . | ICZN |
| Micrellides | Heteronemertea | Gibson (1995) | . | ICZN |
| Micrixalus | Anura | Vitt & Caldwell (2009) | Micrixalidae. | ICZN |
| Microacontias | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Microaerobacter | Bacillales | Khelifi et al. (2010) | . | ICNB |
| Microakodontomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microbacterium | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Microbates | Passeriformes | Clements (2007) | . | ICZN |
| Microbatrachella | Anura | Vitt & Caldwell (2009) | Pyxicephalidae. | ICZN |
| Microberlinia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Microbiota | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Microbispora | Streptosporangiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Microbriza | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Microbryum | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Microbulbifer | Alteromonadales | Garrity et al. (2005) | . | ICNB |
| Microcachrys | Araucariales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Microcaecilia | Gymnophiona | Vitt & Caldwell (2009) | "Caeciliidae". | ICZN |
| Microcalamus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Microcampana | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Microcampylopus | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Microcardiosoma | Haptorida | Lynn (2008) | . | ICZN |
| Microcarpaea | Lamiales | Mabberley (2008) | Linderniaceae. | ICBN |
| Microcaryum | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Microcavia | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microcebus | Primates | McKenna & Bell (1997) | . | ICZN |
| Microcella | Micrococcales | Tiago et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Microcephala | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Microceratium | Ptychodiscales | Fensome et al. (1993) | . | ICBN |
| Microcerculus | Passeriformes | Clements (2007) | . | ICZN |
| Microcetella | Vestibuliferida | Lynn (2008) | . | ICZN |
| Microchaete | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Microcharis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Microchera | Apodiformes | Clements (2007) | . | ICZN |
| Microchilus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microchlamys | Arcellinida | Meisterfeld (2000) | Arcellina -- Microchlamyiidae. | ICZN |
| Microchloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Microchoanostoma | Haptorida | Lynn (2008) | . | ICZN |
| Microcladia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Microcnemum | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Micrococca | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Micrococcus | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Microcodon | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Microcodon | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Microcoelia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microcolax | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Microcoleus | Oscillatoriales | Hoffmann et al. (2005) | . | ICBN |
| Microcometes | | Bass et al. (2009) | Domain Eucarya - Phylum Cercozoa - Class Granofilosea. | ICZN |
| Microcometes | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Lagynidae. | ICZN |
| Microcorycia | Arcellinida | Meisterfeld (2000) | Arcellina -- Microcoryciidae. | ICZN |
| Microcorys | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Microcos | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Microcosmus | Stolidobranchia | Monniot & Monniot (1972); Monniot (2001) | Pyuridae. | ICZN |
| Microcrocis | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Microctenidium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Microcybe | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Microcycas | Cycadales | Mabberley (2008); Christenhusz et al. (2011) | . | ICBN |
| Microcyema | Heterocyemida | Stunkard (1982); Furuya et al. (2007) | . | ICZN |
| Microcystis | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Microcytos | Haplosporida | Bass et al. (2009) | . | ICZN |
| Microdesmis | Malpighiales | Mabberley (2008) | Pandaceae. | ICBN |
| Microdiaphanosoma | Cyrtolophosidida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Microdillus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microdipodops | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microdon | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Microdracoides | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Microdynamis | Cuculiformes | Clements (2007) | . | ICZN |
| Microeca | Passeriformes | Clements (2007) | . | ICZN |
| Microfilum | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Microgale | Afrosoricida | McKenna & Bell (1997); Stanhope et al. (1998) | Tenrecidae. | ICZN |
| Microgastra | Phlebobranchia | Kott (1998) | Plurellidae. | ICZN |
| Microgemma | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Microgilia | Ericales | Mabberley (2008) | Polemoniaceae. | ICBN |
| Microglena | | Kristiansen & Preisig (2001) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. | ICBN |
| Microglomus | Protosteliales | Olive & Stoianovitch (1977) | . | ICBN |
| Microglossa | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Microgramma | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Microgromia | | Bass et al. (2009) | Domain Eucarya - Phylum Cercozoa - Class Granofilosea. | ICZN |
| Microgyne | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Microgynoecium | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Microheliella | Microhelida | Yabuki et al. (2012) | . | ICZN |
| Microhierax | Falconiformes | Clements (2007) | . | ICZN |
| Microhydromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microhydrula | Stauromedusae | Bouillon et al. (2006); Miranda et al. (2010) | Later synonym of Haliclystus. | ICZN |
| Microhyla | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Microhypsibius | Parachela | Kinchin (1994) | . | ICZN |
| Microjoenia | Spirotrichonymphida | Cepicka et al. (2010) | . | ICZN |
| Microlaena | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Microlagenaria | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Microlejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Microlepia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Microlepidium | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Microlepis | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Microliabum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Microlicia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Microligea | Passeriformes | Clements (2007) | . | ICZN |
| Microlobius | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Microloma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Microlophus | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Microlunatus | Propionibacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Micromacronus | Passeriformes | Clements (2007) | . | ICZN |
| Micromastigotes | Spirotrichonymphida | Cepicka et al. (2010) | . | ICZN |
| Micromelum | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Micromeria | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Micrometopion | | Howe et al. (2011) | Domain Eucarya - Phylum Cercozoa - Class Metromonadea. | ICZN |
| Micrometula | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Micromidas | Haptorida | Lynn (2008) | . | ICZN |
| Micromitrium | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Micromonacha | Galbuliformes | Clements (2007) | . | ICZN |
| Micromonas | Clostridiales | Garrity et al. (2005); Tindall & Euzéby (2006) | Later homony. Replaced by Parvimonas. | ICNB |
| Micromonas | Mamiellales | Moestrup (2000); Marin & Melkonian (2010) | . | ICBN |
| Micromonospora | Micromonosporales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Micromurexia | Dasyuromorphia | Groves (2005) | . | ICZN |
| Micromussa | Scleractinia | Veron (2000) | . | ICZN |
| Micromyrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Micromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Micronisus | Falconiformes | Clements (2007) | . | ICZN |
| Micronoma | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Micronuclearia | Micronucleariida | Cavalier-Smith et al. (2008) | . | ICZN |
| Micronychia | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Micronycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Micronyctus | Clevelandellida | Lynn (2008) | . | ICZN |
| Microparra | Charadriiformes | Clements (2007) | . | ICZN |
| Micropechis | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Micropera | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microperoryctes | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Micropeuce | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Micropholis | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Microphyes | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Microphyllum | Rhodymeniales | Schneider & Wynne (2007) | . | ICBN |
| Microphysa | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Micropisthodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Micropleura | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Microplumeria | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Micropolypodium | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Micropora | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Microposthia | Acoela | Faubel & Noreña (2001) | . | ICZN |
| Micropotamogale | Afrosoricida | McKenna & Bell (1997); Stanhope et al. (1998) | Tenrecidae. | ICZN |
| Micropruina | Propionibacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Micropsammella | Tectofilosida | Meisterfeld (2000); Cavalier-Smith & Chao (2003) | Psammonobiotidae. | ICZN |
| Micropsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Micropsitta | Psittaciformes | Clements (2007) | . | ICZN |
| Micropteropus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Micropterygium | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Micropus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Micropygia | Gruiformes | Clements (2007) | . | ICZN |
| Micropyropsis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Micropyrum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Microquadrula | Arcellinida | Meisterfeld (2000) | Difflugina -- Lesquereusiidae. | ICZN |
| Microregma | Haptorida | Lynn (2008) | . | ICZN |
| Microrhinus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Microrhopalodina | Oxymonadida | Brugerolle & Lee (2000) | . | ICZN |
| Microrhopias | Passeriformes | Clements (2007) | . | ICZN |
| Microrphium | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Microryzomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microsaccus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microscalabotes | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Microsciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Microscilla | Cytophagales | Garrity et al. (2005); Ludwig et al. (2011) | . | ICNB |
| Microsciurus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microscleroderma | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Scleritodermidae. | ICZN |
| Microsechium | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Microsentis | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Microseris | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Microsorex | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001); Hutterer (2005) | Later synonym of Sorex. | ICZN |
| Microsorum | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Microspermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Microsphaera | Frankiales | Garrity et al. (2005); Tao et al. (2004) | Later homonym. Replaced by Nakamurella. | ICNB |
| Microspiretta | Stichotrichida | Lynn (2008) | . | ICZN |
| Microstachys | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Microstegium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Microsteira | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Microstigma | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Microstilbon | Apodiformes | Clements (2007) | . | ICZN |
| Microstrobos | Araucariales | Farjon (2001); Christenhusz et al. (2011) | Later synonym of Pherosphaera. | ICBN |
| Microtatorchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microtea | Caryophyllales | Mabberley (2008) | Phytolaccaceae. | ICBN |
| Microterangis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microterricola | Micrococcales | Matsumoto et al. (2008); Ludwig et al. (2012) | . | ICNB |
| Microtetraspora | Streptosporangiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Microthamnion | Microthamniales | Lewis & McCourt (2004) | . | ICBN |
| Microtheciella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Microthelys | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microthorax | Microthoracida | Lynn (2008) | . | ICZN |
| Microtis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Microtoena | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Microtropis | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Microtus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Microtylostylifer | Poecilosclerida | Hajdu & Van Soest (2002) | . | ICZN |
| Microula | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Microvirga | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Microvirgula | Neisseriales | Garrity et al. (2005) | . | ICNB |
| Microxina | Haplosclerida | Desqueyroux-Faúndez & Valentine (2002) | . | ICZN |
| Microxistyla | Halichondrida | Hooper (2002) | . | ICZN |
| Microxysma | Dysteriida | Lynn (2008) | . | ICZN |
| Micruncus | Haptorida | Lynn (2008) | . | ICZN |
| Micrundella | Tintinnida | Lynn (2008) | . | ICZN |
| Micrura | Heteronemertea | Gibson (1995) | . | ICZN |
| Micrurides | Heteronemertea | Gibson (1995) | . | ICZN |
| Micrurimorpha | Heteronemertea | Gibson (1995) | . | ICZN |
| Micrurina | Heteronemertea | Gibson (1995) | . | ICZN |
| Micrurinella | Heteronemertea | Gibson (1995) | . | ICZN |
| Micruroides | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Micrurus | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Micryletta | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Mictopholis | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Mida | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Mielichhoferia | Bryales | Goffinet et al. (2009) | . | ICBN |
| Miersia | Asparagales | Mabberley (2008) | Alliaceae. | ICBN |
| Miersiella | Dioscoreales | Mabberley (2008) | Burmanniaceae. | ICBN |
| Migros | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Pseudogaudryinidae. | ICZN |
| Mikamiella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Mikania | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mikaniopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mikrocodides | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Mila | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Mildbraedia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Mildbraediodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mildella | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Milesina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Discorbinellidae. | ICZN |
| Miliammellus | Silicoloculinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992); Sen Gupta (1999) | Silicoloculinidae. | ICZN |
| Miliammina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rzehakinidae. | ICZN |
| Milicia | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Miliolinella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Milium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Miliusa | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Milla | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Millardia | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Millardiana | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Millepora | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Milleria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Millettia | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Millettiidae. | ICZN |
| Millettia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Millettiana | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Cymbaloporidae. | ICZN |
| Milligania | Asparagales | Mabberley (2008) | Asteliaceae. | ICBN |
| Millingtonia | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Millisia | Corynebacteriales | Soddell et al. (2006); Ludwig et al. (2012) | . | ICNB |
| Millotia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Milnesium | Apochela | Kinchin (1994) | . | ICZN |
| Miltitzia | Boraginales | Mabberley (2008) | Hydrophyllaceae. | ICBN |
| Miltonia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Miltoniopsis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Milvago | Falconiformes | Clements (2007) | . | ICZN |
| Milvus | Falconiformes | Clements (2007) | . | ICZN |
| Mimetanthe | Lamiales | Mabberley (2008) | Phrymaceae. | ICBN |
| Mimetes | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Mimetillus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mimetridium | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Mimizuku | Strigiformes | Clements (2007) | . | ICZN |
| Mimon | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mimophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Mimophrya | Astomatida | Lynn (2008) | . | ICZN |
| Mimophytum | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Mimosa | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mimosina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trimosinidae. | ICZN |
| Mimosiphonops | Gymnophiona | Vitt & Caldwell (2009) | "Caeciliidae". | ICZN |
| Mimozyganthus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mimulicalyx | Lamiales | Mabberley (2008) | Phrymaceae. | ICBN |
| Mimulopsis | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Mimulus | Lamiales | Mabberley (2008) | Phrymaceae. | ICBN |
| Mimus | Passeriformes | Clements (2007) | . | ICZN |
| Mimusops | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Minabea | Alcyonacea | Bayer (1981) | Alcyoniidae. | ICZN |
| Minakatella | Liceales | Yamamoto (1998) | . | ICBN |
| Minaria | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Minasia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Minchinella | Lithonida | Vacelet et al. (2002) | . | ICZN |
| Minchinia | Haplosporida | Bass et al. (2009) | . | ICZN |
| Mindeniella | Rhipidiales | Dick (2001); Kirk et al. (2008) | Rhipidiaceae. | ICBN |
| Minerva | Bangiales | Schneider & Wynne (2007) | . | ICBN |
| Minervarya | Anura | Vitt & Caldwell (2009) | Dicroglossidae. | ICZN |
| Miniacina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Homotrematidae. | ICZN |
| Minibiotus | Parachela | Kinchin (1994) | . | ICZN |
| Minictena | Cydippida | Carré & Carré (1993) | . | ICZN |
| Miniimonas | Micrococcales | Ue et al. (2011); Ludwig et al. (2012) | . | ICNB |
| Minimassisteria | Leucodictyida | Howe et al. (2011) | . | ICZN |
| Miniopterus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Minipera | Stolidobranchia | Monniot (2001) | Pyuridae. | ICZN |
| Ministeria | Ministeriida | Cavalier-Smith (1998) | . | ICZN |
| Minium | Rhodymeniales | Schneider & Wynne (2007) | . | ICBN |
| Minla | Passeriformes | Clements (2007) | . | ICZN |
| Mino | Passeriformes | Clements (2007) | . | ICZN |
| Minquartia | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Minthostachys | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Minuartia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Minuisis | Alcyonacea | Bayer (1981) | Isididae. | ICZN |
| Minuria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Minuscula | Peridiniales | Fensome et al. (1993) | . | ICBN |
| Minutanemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Minyas | Actiniaria | Fautin et al. (2007) | Junior homonym. Replaced by Actinecta. | ICZN |
| Minyobates | Anura | Vitt & Caldwell (2009) | Dendrobatidae. | ICZN |
| Minyplanetes | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Mionandra | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Mionectes | Passeriformes | Clements (2007) | . | ICZN |
| Miopithecus | Primates | Groves (2005) | . | ICZN |
| Miquelia | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Miqueliopuntia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Mirabilis | Caryophyllales | Mabberley (2008) | Nyctaginaceae. | ICBN |
| Miracella | Phaeogymnocellida | Takahashi & Anderson (2000) | . | ICZN |
| Mirafra | Passeriformes | Clements (2007) | . | ICZN |
| Miraglossum | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mirandea | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Mirbelia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Miricacalia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mirodysteria | Dysteriida | Lynn (2008) | . | ICZN |
| Mirofolliculina | Heterotrichida | Lynn (2008) | . | ICZN |
| Mironia | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Miroscyllium | Squaliformes | Nelson (2006) | . | ICZN |
| Mirounga | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Mirza | Primates | Groves (2005) | . | ICZN |
| Misacineta | Evaginogenida | Lynn (2008) | . | ICZN |
| Misbrookea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Miscanthus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mischarytera | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Mischobulbum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mischocarpus | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Mischococcus | Mischococcales | Ettl (1978) | . | ICBN |
| Mischodon | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Mischogyne | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Misodendrum | Santalales | Mabberley (2008) | Misodendraceae. | ICBN |
| Misopates | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Mississippina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Mississippinidae. | ICZN |
| Mistarcon | Exogenida | Lynn (2008) | . | ICZN |
| Mistoprayina | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Mitchella | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mitella | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Mitostemma | Malpighiales | Mabberley (2008) | Passifloraceae. | ICBN |
| Mitostigma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mitracarpus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mitragyna | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mitranthes | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Mitrantia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Mitraria | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Mitrasacme | Gentianales | Mabberley (2008) | Loganiaceae. | ICBN |
| Mitrasacmopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mitrastema | Malpighiales | Mabberley (2008); Reveal (2010) | Orthographic variant of "Mitrastemon." Conservation of "Mitrastemon" was proposed by Reveal (2010). | ICBN |
| Mitrastemma | Malpighiales | Mabberley (2008); Reveal (2010) | Original incorrect spelling of "Mitrastemon." Conservation of "Mitrastemon" was proposed by Reveal (2010). | ICBN |
| Mitrastemon | Malpighiales | Mabberley (2008); Reveal (2010) | Conservation of "Mitrastemon" against "Mitrastema" and "Mitrastemma" was proposed by Reveal (2010). | ICBN |
| Mitrella | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Mitreola | Gentianales | Mabberley (2008) | Loganiaceae. | ICBN |
| Mitrephanes | Passeriformes | Clements (2007) | . | ICZN |
| Mitrephora | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Mitriostigma | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mitrobryum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Mitrocoma | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Mitrocomella | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Mitrophyllum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Mitrospingus | Passeriformes | Clements (2007) | . | ICZN |
| Mitsuaria | Burkholderiales | Amakata et al. (2005) | . | ICNB |
| Mitsukurina | Lamniformes | Nelson (2006) | . | ICZN |
| Mitsuokella | Selenomonadales | Garrity et al. (2005); Marchandin et al. (2010) | . | ICNB |
| Mittenia | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Mittenothamnium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Mitthyridium | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Mitu | Galliformes | Clements (2007) | . | ICZN |
| Miuraea | Bangiales | Sutherland et al. (2011) | . | ICBN |
| Mixibius | Parachela | Kinchin (1994) | . | ICZN |
| Mixolineus | Heteronemertea | Gibson (1995) | . | ICZN |
| Mixophyes | Anura | Vitt & Caldwell (2009) | Myobatrachidae. | ICZN |
| Mixotricha | Cristamonadida | Cepicka et al. (2010) | . | ICZN |
| Mixtophrya | Astomatida | Lynn (2008) | . | ICZN |
| Miyabea | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Miyamayomena | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mizutania | Metzgeriales | Crandall-Stotler et al. (2009) | . | ICBN |
| Mkilua | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Mnemiopsis | Lobata | Harbison & Madin (1982) | . | ICZN |
| Mnesithea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mniobia | Bdelloida | Segers (2002); Segers (2007) | . | ICZN |
| Mniobryoides | Bryales | Goffinet et al. (2009) | . | ICBN |
| Mniochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mniodendron | Hypnodendrales | Goffinet et al. (2009) | . | ICBN |
| Mniodes | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mnioloma | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Mniomalia | Bryales | Goffinet et al. (2009) | . | ICBN |
| Mniotilta | Passeriformes | Clements (2007) | . | ICZN |
| Mnium | Bryales | Goffinet et al. (2009) | . | ICBN |
| Moacroton | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Mobilabium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mobilicoccus | Micrococcales | Hamada et al. (2010); Ludwig et al. (2012) | Dermatophilaceae. | ICNB |
| Mobiluncus | Actinomycetales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Mobula | Myliobatiformes | Nelson (2006) | . | ICZN |
| Mochlus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Mocquerysia | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Modeeria | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Modestobacter | Frankiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Modicisalibacter | Oceanospirillales | Ben Ali Gam et al. (2007) | . | ICNB |
| Modiola | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Modiolastrum | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Modulatrix | Passeriformes | Clements (2007) | . | ICZN |
| Moebjergarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Moehringia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Moellerella | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Moenchia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Moerckia | Fossombroniales | He-Nygrén et al. (2006); Crandall-Stotler et al. (2009) | . | ICBN |
| Moerisia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Moestrupia | | Hansen & Daugbjerg (2011) | . | ICBN |
| Mogera | Soricomorpha | Hutterer (2005) | . | ICZN |
| Mogibacterium | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Mogoltavia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mohavea | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Moho | Passeriformes | Clements (2007) | . | ICZN |
| Mohoua | Passeriformes | Clements (2007) | . | ICZN |
| Mojavia | Nostocales | Rehakova et al. (2007) | . | ICBN |
| Moldenhawera | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Molendoa | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Molgula | Stolidobranchia | Monniot & Monniot (1972); Monniot (2001) | Molgulidae. | ICZN |
| Molguloides | Stolidobranchia | Monniot & Monniot (1972); Monniot (2001) | Molgulidae. | ICZN |
| Molinadendron | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Molinaea | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Molineria | Asparagales | Mabberley (2008) | Hypoxidaceae. | ICBN |
| Molinia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mollia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Mollimonas | Glissomonadida | Howe et al. (2011) | . | ICZN |
| Mollinedia | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Mollisquama | Squaliformes | Nelson (2006) | . | ICZN |
| Mollugo | Caryophyllales | Mabberley (2008) | Molluginaceae. | ICBN |
| Molluskocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Moloch | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Molongum | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Molopanthera | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Molopospermum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Molossops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Molossus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Molothrus | Passeriformes | Clements (2007) | . | ICZN |
| Moltkia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Moltkiopsis | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Moluccella | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Mommsenia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Momordica | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Momotus | Coraciiformes | Clements (2007) | . | ICZN |
| Monachather | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Monachella | Passeriformes | Clements (2007) | . | ICZN |
| Monachosorum | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Monachus | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Monactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Monactis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monallantus | Mischococcales | Ettl (1978) | . | ICBN |
| Monalysidium | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Peneroplidae. | ICZN |
| Monanchora | Poecilosclerida | Van Soest (2002) | . | ICZN |
| Monandrocarpa | Stolidobranchia | Monniot & Monniot (1972) | Styelidae. | ICZN |
| Monanthes | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Monanthochloe | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Monanthocitrus | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Monanthotaxis | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Monarcha | Passeriformes | Clements (2007) | . | ICZN |
| Monarda | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Monardella | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Monarrhenus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monarthrocarpus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Monasa | Galbuliformes | Clements (2007) | . | ICZN |
| Monaster | Ptychodiscales | Fensome et al. (1993) | . | ICBN |
| Mondia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Monelytrum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Moneses | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Moneuplotes | Euplotida | Lynn (2008) | . | ICZN |
| Mongoliicoccus | Cytophagales | Liu et al. (2012) | . | ICNB |
| Mongoliitalea | Cytophagales | Yang et al. (2012) | . | ICNB |
| Monias | Gruiformes | Clements (2007) | . | ICZN |
| Monilaria | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Monilicaryon | Haptorida | Lynn (2008) | . | ICZN |
| Moniliformis | Moniliformida | Amin (1985) | . | ICZN |
| Monimia | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Monimiastrum | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Monimopetalum | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Monintranstylum | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Monizia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Monniera | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Monnina | Fabales | Mabberley (2008) | Polygalaceae. | ICBN |
| Monniotus | Aplousobranchia | Kott (1998) | Protopolyclinidae. | ICZN |
| Monobotryllus | Stolidobranchia | Monniot & Monniot (1972); Kott (1998) | Junior synonym of Polyzoa. | ICZN |
| Monobrachium | Limnomedusae | Bouillon et al. (2006) | . | ICZN |
| Monocarpia | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Monocarpus | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Monocercomonas | Tritrichomonadida | Cepicka et al. (2010) | . | ICZN |
| Monocercomonoides | Oxymonadida | Brugerolle & Lee (2000) | . | ICZN |
| Monochaetum | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Monochasma | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Monochilum | Tetrahymenida | Lynn (2008) | . | ICZN |
| Monochilus | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Monochoria | Commelinales | Mabberley (2008) | Pontederiaceae. | ICBN |
| Monochrysis | | Kristiansen & Preisig (2001) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. | ICBN |
| Monoclea | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Monococcus | Caryophyllales | Mabberley (2008) | Phytolaccaceae. | ICBN |
| Monocoronella | Urostylida | Chen et al. (2011) | . | ICZN |
| Monocoryne | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Monocosta | Acanthoecida | Leadbeater & Thomsen (2000) | . | ICZN |
| Monocostus | Zingiberales | Mabberley (2008) | Costaceae. | ICBN |
| Monocrepidium | Halichondrida | Alvarez & Van Soest (2002) | . | ICZN |
| Monoculus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monocyclanthus | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Monocymbium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Monocystella | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Monocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Monodactylopsis | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Monodelphis | Ameridelphia | McKenna & Bell (1997) | . | ICZN |
| Monodia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Monodinium | Haptorida | Lynn (2008) | . | ICZN |
| Monodon | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Monodontophrya | Astomatida | Lynn (2008) | . | ICZN |
| Monodopsis | Eustigmatales | Hibberd (1981): Hegewald et al. (2007) | . | ICBN |
| Monodora | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Monoductus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Monodus | Mischococcales | Ettl (1978) | . | ICBN |
| Monogereion | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monogramma | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Monohedotrochus | Scleractinia | Kitahara & Cairns (2005) | . | ICZN |
| Monoica | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Monolena | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Monolepis | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Monolopia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monomastix | Monomastigales | Marin & Melkonian (2010) | . | ICBN |
| Monomeria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Monommata | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Monomorphina | Euglenales | Marin et al. (2003) | . | ICBN |
| Monomyces | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Mononemertes | Pelagica | Gibson (1995) | . | ICZN |
| Monopeltis | Squamata | Vitt & Caldwell (2009) | Amphisbaenidae. | ICZN |
| Monopera | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Monophrynium | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Monophyllaea | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Monophyllanthe | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Monophyllorchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Monophyllus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Monoplectroninia | Lithonida | Vacelet et al. (2002) | . | ICZN |
| Monoporus | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Monoposthium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Monopsis | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Monopteryx | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Monoptilon | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monopyle | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Monopylocystis | Lyromonadida | O'Kelly et al. (2003); Cavalier-Smith & Nikolaev (2008) | . | ICZN |
| Monorhaphis | Amphidiscosida | Tabachnick (2002) | . | ICZN |
| Monosalpinx | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Monoserius | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Monosiga | Craspedida | Leadbeater & Thomsen (2000) | . | ICZN |
| Monosolenium | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Monosporus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Monostaechas | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Monotagma | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Monotalea | Lituolida | Kaminski (2000) | Monotaleinae, Verneuilinacea. | ICZN |
| Monotaxis | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Monotes | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Monotheca | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Monothecella | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Monothecium | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Monotoca | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Monotrema | Poales | Mabberley (2008) | Rapateaceae. | ICBN |
| Monotrichomonas | Honigbergiellida | Cepicka et al. (2010) | . | ICZN |
| Monotropa | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Monotropastrum | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Monotropsis | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Monsonia | Geraniales | Mabberley (2008) | Geraniaceae. | ICBN |
| Monstera | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Montanoa | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Montaspis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Montastraea | Scleractinia | De Blainville (1830); Cairns et al. (1999); Veron (2000) | Not "Montastrea". | ICZN |
| Montatheris | Squamata | Mattison (2007); Vitt & Caldwell (2009) | Serpentes. Viperidae. Not "Monatatheris". | ICZN |
| Monteiroa | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Montemaria | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Montfortella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Cibicididae. | ICZN |
| Montia | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Monticalia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Monticola | Passeriformes | Clements (2007) | . | ICZN |
| Monticolomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Montifringilla | Passeriformes | Clements (2007) | . | ICZN |
| Montigena | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Montigyra | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Montinia | Solanales | Mabberley (2008) | Montiniaceae. | ICBN |
| Montiopsis | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Montipora | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Montrichardia | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Montrouziera | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Monttea | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Monurceolaria | Mobilida | Lynn (2008) | . | ICZN |
| Moolabalia | Alcyonacea | Alderslade (2001) | Clavulariidae. | ICZN |
| Moonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Moorea | Oscillatoriales | Engene et al. (2012) | . | ICBN |
| Moorella | Thermoanaerobacterales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Moorochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mopsea | Alcyonacea | Bayer (1981) | Isididae. | ICZN |
| Mopsechiniscus | Echiniscoidea | Kinchin (1994) | . | ICZN |
| Mopsella | Alcyonacea | Bayer (1981) | Melithaeidae. | ICZN |
| Moquiniella | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Mora | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Moraea | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Moratia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Moraxella | Pseudomonadales | Garrity et al. (2005) | . | ICNB |
| Morchellana | Alcyonacea | Bayer (1981) | Nephtheidae. | ICZN |
| Morchellium | Aplousobranchia | Kott (1998) | Polyclinidae. | ICZN |
| Mordacia | Petromyzontiformes | Nelson (2006) | . | ICZN |
| Morelia | Squamata | Vitt & Caldwell (2009) | Serpentes. Pythonidae. | ICZN |
| Morelia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Morella | Fagales | Mabberley (2008) | Myricaceae. | ICBN |
| Morelotia | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Morenia | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Morethia | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Morettia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Morganella | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Morgania | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Moricandia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Moriera | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Morierina | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Morina | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Morinda | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Morindopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Moringa | Brassicales | Mabberley (2008) | Moringaceae. | ICBN |
| Morisia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Morisonia | Brassicales | Mabberley (2008) | Capparaceae. | ICBN |
| Moritella | Alteromonadales | Garrity et al. (2005) | . | ICNB |
| Morithamnus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Moritizia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Morkillia | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Mormodes | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mormolyca | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mormoops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mormopterus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Morococcus | Neisseriales | Garrity et al. (2005) | . | ICNB |
| Morococcyx | Cuculiformes | Clements (2007) | . | ICZN |
| Moronobea | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Morphnus | Falconiformes | Clements (2007) | . | ICZN |
| Morrenia | Gentianales | Mabberley (2008); Rapini et al. (2011) | Later synonym of Araujia. | ICBN |
| Morsacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Mortensenia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Mortonia | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Mortoniella | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mortoniodendron | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Morulaeplecta | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spiroplectamminidae. | ICZN |
| Morunasaurus | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Morus | Pelecaniformes | Clements (2007) | . | ICZN |
| Morus | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Moryella | Clostridiales | Carlier et al. (2007) | . | ICNB |
| Mosannona | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Moscharia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Moschiola | Artiodactyla | Grubb (2005) | . | ICZN |
| Moschopsis | Asterales | Mabberley (2008) | Calyceraceae. | ICBN |
| Moschus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Mosdenia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Moseleya | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Moseniella | Splachnales | Goffinet et al. (2009) | . | ICBN |
| Moseria | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Mosia | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mosiera | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Mosla | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Mosquitoxylum | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Mossia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Mostacillastrum | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Mostuea | Gentianales | Mabberley (2008) | Gelsemiaceae. | ICBN |
| Motacilla | Passeriformes | Clements (2007) | . | ICZN |
| Motandra | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Motherwellia | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Motilibacter | Frankiales | Lee (2012); Ludwig et al. (2012) | . | ICNB |
| Motleyia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mougeotia | Zygnematales | Gontcharov (2008) | . | ICBN |
| Mougeotiopsis | Zygnematales | Gontcharov (2008) | . | ICBN |
| Moullava | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Moultonianthus | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Mourera | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Mouretia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mouriri | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Moussonia | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Moutabea | Fabales | Mabberley (2008) | Polygalaceae. | ICBN |
| Moya | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Mozaffariania | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mrazekia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Mrazekiella | Astomatida | Lynn (2008) | . | ICZN |
| Msuata | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mtonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Mucidosphaerium | Chlorellales | Bock et al. (2011) | . | ICBN |
| Mucilaginibacter | Sphingobacteriales | Pankratov et al. (2007) | . | ICNB |
| Mucilago | Physarales | Yamamoto (1998) | . | ICBN |
| Mucispirillum | Geovibriales | Robertson et al. (2005) | . | ICNB |
| Mucoa | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Mucophrya | Endogenida | Lynn (2008) | . | ICZN |
| Mucosphaera | Chromulinales | Kristiansen & Preisig (2001) | Chromulinaceae (uniflagellate). | ICBN |
| Mucotrichidium | Stichotrichida | Lynn (2008) | . | ICZN |
| Mucronea | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Mucronina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nodosariidae. | ICZN |
| Mucuna | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Muehlenbeckia | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Muellera | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Muelleranthus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Muellerargia | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Muellerena | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Muellerina | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Muellerobryum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Muellerolimon | Caryophyllales | Mabberley (2008) | Plumbaginaceae. | ICBN |
| Muggiaea | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Muhlenbergia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Muilla | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Muiradinium | Peridiniales | Fensome et al. (1993) | Holocene. | ICBN |
| Muiriantha | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Muiriella | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae - Subclass Peridiniphycidae. Holocene. | ICBN |
| Mukdenia | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Mukundaella | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Mulinum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mulleripicus | Piciformes | Clements (2007) | . | ICZN |
| Mullerochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Mullinia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Alfredinidae. | ICZN |
| Mullinoides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Asterigerinatidae. | ICZN |
| Multicilia | Holomastigida | Cavalier-Smith (1996/97) | . | ICZN |
| Multidentia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Multifasciculatum | Evaginogenida | Lynn (2008) | . | ICZN |
| Multifidella | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Eggerellidae. | ICZN |
| Multimonas | Apusomonadida | Cavalier-Smith & Chao (2010) | . | ICZN |
| Multisentis | Oligacanthorhynchida | Smales (1997) | Oligacanthorhynchida. | ICZN |
| Multispinula | Peridiniales | Fensome et al. (1993) | Holocene. | ICBN |
| Mundulea | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mungos | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Mungotictis | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Muniziella | Vestibuliferida | Lynn (2008) | . | ICZN |
| Munnozia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Munroa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Munroidendron | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Munronia | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Muntiacus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Muntingia | Malvales | Mabberley (2008) | Muntingiaceae. | ICBN |
| Munzothamnus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Muraltia | Fabales | Mabberley (2008) | Polygalaceae. | ICBN |
| Murbeckiella | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Murchisonia | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Murdannia | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Murdochiella | Clostridiales | Ulger-Toprak et al. (2010) | . | ICNB |
| Murexechinus | Dasyuromorphia | Groves (2005) | . | ICZN |
| Murexia | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Muricaria | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Muricauda | Flavobacteriales | Garrity et al. (2005) | . | ICNB |
| Muriceides | Alcyonacea | Bayer (1981) | Plexauridae. | ICZN |
| Muricella | Alcyonacea | Bayer (1981) | Acanthogorgiidae. | ICZN |
| Muricellisis | Alcyonacea | Bayer (1981) | Isididae. | ICZN |
| Muriceopsis | Alcyonacea | Bayer (1981) | Plexauridae. | ICZN |
| Muricoccus | Rhodospirillales | Garrity et al. (2005)); Sánchez-Porro et al. (2009) | Later synonym of Roseomonas. | ICNB |
| Muriculus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Muriella | Chlorellales | Neustupa et al. (2011) | . | ICBN |
| Muriicola | Flavobacteriales | Kahng et al. (2010) | . | ICNB |
| Murina | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Murinocardiopsis | Streptosporangiales | Kämpfer et al. (2010); Ludwig et al. (2012) | Nocardiopsaceae. | ICNB |
| Murraya | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Murrayella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Murrayinella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glabratellidae. | ICZN |
| Murrayon | Parachela | Kinchin (1994) | . | ICZN |
| Murrayona | Murrayonida | Vacelet et al. (2002) | . | ICZN |
| Mus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Musa | Zingiberales | Mabberley (2008) | Musaceae. | ICBN |
| Musajevella | Kiitrichida | Lynn (2008) | . | ICZN |
| Musanga | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Muscardinus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Muscari | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Muschleria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Muscicapa | Passeriformes | Clements (2007) | . | ICZN |
| Muscicapella | Passeriformes | Clements (2007) | . | ICZN |
| Muscigralla | Passeriformes | Clements (2007) | . | ICZN |
| Muscipipra | Passeriformes | Clements (2007) | . | ICZN |
| Muscipula | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Muscisaxicola | Passeriformes | Clements (2007) | . | ICZN |
| Muscoherzogia | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Musella | Zingiberales | Mabberley (2008) | Musaceae. | ICBN |
| Musellifer | Chaetonotida | Balsamo et al. (2009); Hummon & Todaro (2010) | . | ICZN |
| Musgravea | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Musineon | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Musonycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Musophaga | Cuculiformes | Clements (2007) | . | ICZN |
| Mussa | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Mussaenda | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mussaendopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Musschia | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Mussismilia | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Mustela | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Mustelus | Carcharhiniformes | Nelson (2006) | . | ICZN |
| Mutellina | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Mutisia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Myadestes | Passeriformes | Clements (2007) | . | ICZN |
| Myagrum | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Mycale | Poecilosclerida | Van Soest & Hajdu (2002) | . | ICZN |
| Mycedium | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Myceligenerans | Micrococcales | Cui et al. (2004); Ludwig et al. (2012) | . | ICNB |
| Myceliospongia | | Vacelet et al. (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae. | ICZN |
| Mycerinus | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Mycerobas | Passeriformes | Clements (2007) | . | ICZN |
| Mycetia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Mycetocola | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Mycetophyllia | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Mychodea | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Mychodeophyllum | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Mychostomina | Spirillinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spirillinidae. | ICZN |
| Mycobacterium | Corynebacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Mycochrysis | Ochromonadales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Chromulinaceae (biflagellate). | ICBN |
| Mycoplana | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Mycoplasma | Mycoplasmatales | Garrity et al. (2005) | . | ICNB |
| Mycteria | Ciconiiformes | Clements (2007) | . | ICZN |
| Mycterothrix | Colpodida | Lynn (2008) | . | ICZN |
| Mydaus | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Myersinella | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Myersiohyla | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Myersophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Myiagra | Passeriformes | Clements (2007) | . | ICZN |
| Myiarchus | Passeriformes | Clements (2007) | . | ICZN |
| Myiobius | Passeriformes | Clements (2007) | . | ICZN |
| Myioborus | Passeriformes | Clements (2007) | . | ICZN |
| Myiodynastes | Passeriformes | Clements (2007) | . | ICZN |
| Myiopagis | Passeriformes | Clements (2007) | . | ICZN |
| Myioparus | Passeriformes | Clements (2007) | . | ICZN |
| Myiophobus | Passeriformes | Clements (2007) | . | ICZN |
| Myiopsitta | Psittaciformes | Clements (2007) | . | ICZN |
| Myiornis | Passeriformes | Clements (2007) | . | ICZN |
| Myiotheretes | Passeriformes | Clements (2007) | . | ICZN |
| Myiotriccus | Passeriformes | Clements (2007) | . | ICZN |
| Myiozetetes | Passeriformes | Clements (2007) | . | ICZN |
| Mykophagophrys | Colpodida | Lynn (2008) | . | ICZN |
| Mylestoma | Odontostomatida | Lynn (2008) | . | ICZN |
| Mylia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Myliobatis | Myliobatiformes | Nelson (2006) | . | ICZN |
| Myliusia | Hexactinosida | Reiswig & Wheeler (2002) | . | ICZN |
| Mylomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myobatrachus | Anura | Vitt & Caldwell (2009) | Myobatrachidae. | ICZN |
| Myocastor | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myodes | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Myodocarpus | Apiales | Mabberley (2008) | Myodocarpaceae. | ICBN |
| Myoictis | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Myoisophagos | Heteronemertea | Gibson (1995); Kajihara et al. (2008) | Junior synonym of Ramphogordius. | ICZN |
| Myomimus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myomys | Rodentia | McKenna & Bell (1997); Musser & Carleton (2005) | Later synonym of Mastomys. | ICZN |
| Myomyscus | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Myonanthus | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Myonima | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Myonycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Myopea | Acoela | Crezée (1975) | . | ICZN |
| Myophonus | Passeriformes | Clements (2007) | . | ICZN |
| Myopordon | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Myoporum | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Myoprocta | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myopterus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Myopus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myorhynchonemertes | Heteronemertea | Kajihara et al. (2008) | . | ICZN |
| Myornis | Passeriformes | Clements (2007) | . | ICZN |
| Myoschilos | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Myoschiston | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Myosciurus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myoscyphidia | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Myosoma | Coloniales | Emschermann (1972); Nielsen (1982) | Pedicellinidae. | ICZN |
| Myosorex | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Myosotidium | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Myosotis | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Myosoton | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Myospalax | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Myosurus | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Myotis | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Myotomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Myoxanthus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Myoxus | Rodentia | McKenna & Bell (1997); Holden (2005) | Later synonym of Glis. | ICZN |
| Myrceugenia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrcia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrcianthes | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrciaria | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myriactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Myriactis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Myrialepis | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Myrianthus | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Myriaspora | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Myrica | Fagales | Mabberley (2008) | Myricaceae. | ICBN |
| Myricanthe | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Myricaria | Caryophyllales | Mabberley (2008) | Tamaricaceae. | ICBN |
| Myrinia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Myriocarpa | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Myriocephalus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Myriocladus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Myriocolea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Myriocoleopsis | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Myriogramme | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Myriokaryon | Haptorida | Lynn (2008) | . | ICZN |
| Myriolimon | Caryophyllales | Mabberley (2008) | Plumbaginaceae. | ICBN |
| Myrionecta | Cyclotrichiida | Lynn (2008) | . | ICZN |
| Myrionema | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Myriopathes | Antipatharia | Opresko (2001) | . | ICZN |
| Myriophyllum | Saxifragales | Mabberley (2008) | Haloragaceae. | ICBN |
| Myriopteron | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Myriospora | Protococcidiorida | Perkins et al. (2000) | . | ICZN |
| Myriosporides | Protococcidiorida | Perkins et al. (2000) | . | ICZN |
| Myriostachya | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Myripnois | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Myristica | Magnoliales | Mabberley (2008) | Myristicaceae. | ICBN |
| Myrmechis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Myrmecia | Trebouxiales | Friedl (1995) | . | ICBN |
| Myrmeciza | Passeriformes | Clements (2007) | . | ICZN |
| Myrmecobius | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Myrmecocichla | Passeriformes | Clements (2007) | . | ICZN |
| Myrmecodia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Myrmeconauclea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Myrmecophaga | Xenarthra | McKenna & Bell (1997) | . | ICZN |
| Myrmekioderma | Halichondrida | Hooper (2002) | . | ICZN |
| Myrmephytum | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Myrmia | Apodiformes | Clements (2007) | . | ICZN |
| Myrmoborus | Passeriformes | Clements (2007) | . | ICZN |
| Myrmochanes | Passeriformes | Clements (2007) | . | ICZN |
| Myrmorchilus | Passeriformes | Clements (2007) | . | ICZN |
| Myrmornis | Passeriformes | Clements (2007) | . | ICZN |
| Myrmothera | Passeriformes | Clements (2007) | . | ICZN |
| Myrmotherula | Passeriformes | Clements (2007) | . | ICZN |
| Myrocarpus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Myroides | Flavobacteriales | Garrity et al. (2005) | . | ICNB |
| Myron | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Myrosma | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Myrosmodes | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Myrospermum | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Myrothamnus | Gunnerales | Mabberley (2008) | Myrothamnaceae. | ICBN |
| Myroxylon | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Myrrhidendron | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Myrrhinium | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrrhis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Myrsine | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Myrtama | Caryophyllales | Mabberley (2008) | Tamaricaceae. | ICBN |
| Myrtastrum | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrtella | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrteola | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Myrtillocactus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Myrtis | Apodiformes | Clements (2007) | . | ICZN |
| Myrtopsis | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Myrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Mysanthus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Mysateles | Rodentia | Woods & Kilpatrick (2005) | . | ICZN |
| Mystacidium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Mystacina | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Mystacornis | Passeriformes | Clements (2007) | . | ICZN |
| Mysticella | Peridiniales | Carbonell-Moore (1994) | . | ICBN |
| Mystromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Mystropetalon | Santalales | Mabberley (2008) | Balanophoraceae. | ICBN |
| Mystroxylon | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Mytilaria | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Mytilina | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Mytilophilus | Pleuronematida | Lynn (2008) | . | ICZN |
| Mytilopsis | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Myurella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Myurium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Myuroclada | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Myxidium | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Myxilla | Poecilosclerida | Van Soest (2002) | . | ICZN |
| Myxine | Myxiniformes | Nelson (2006) | . | ICZN |
| Myxobaktron | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Myxobilatus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Myxobolus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Myxochloris | Rhizochloridales | Ettl (1978) | . | ICBN |
| Myxochrysis | | Kristiansen & Preisig (2001) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. | ICBN |
| Myxococcus | Myxococcales | Garrity et al. (2005) | . | ICNB |
| Myxodictyium | | Bass et al. (2009) | Domain Eucarya - Rhizaria - incertae sedis - Family Rhizoplasmidae. | ICZN |
| Myxodinium | | Fensome et al. (1993); Skovgaard et al. (2007) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Dinozoa - Class Dinophyceae. Former Blastodiniales. | ICBN |
| Myxodoryx | Poecilosclerida | Van Soest (2002) | . | ICZN |
| Myxohyella | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Myxopappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Myxoproteus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Myxopyrum | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Myxosarcina | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Myxotheca | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Lagynidae. | ICZN |
| Myza | Passeriformes | Clements (2007) | . | ICZN |
| Myzocytiopsis | Myzocytiopsidales | Dick (2001); Kirk et al. (2008) | Myzocytiopsidaceae. | ICBN |
| Myzocytium | Pythiales | Dick (2001); Kirk et al. (2008) | Pythiaceae. | ICBN |
| Myzomela | Passeriformes | Clements (2007) | . | ICZN |
| Myzopoda | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Myzornis | Passeriformes | Clements (2007) | . | ICZN |
| N | |
| Nabaluia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nabalus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nabranella | Arcellinida | Snegovaya & Alekperov (2009) | Closely related to Pontigulasia?. | ICZN |
| Naccaria | Bonnemaisoniales | Schneider & Wynne (2007) | . | ICBN |
| Nactus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Nadelspora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nadina | Acoela | Dörjes (1968); Faubel & Noreña (2001) | . | ICZN |
| Nadinella | Tectofilosida | Meisterfeld (2000); Cavalier-Smith & Chao (2003) | Psammonobiotidae. | ICZN |
| Nadzikambia | Squamata | Tilbury & Tolley (2009) | Chamaeleonidae. | ICZN |
| Naegeliella | Hibberdiales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Chrysocapsaceae (biflagellate). | ICBN |
| Naegleria | Schizopyrenida | Patterson et al. (2000) | . | ICZN |
| Naemorhedus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Nageia | Araucariales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Nageliella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Naiadocystis | Eugregarinorida | Clopton et al. (2004) | . | ICZN |
| Naja | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Najas | Alismatales | Mabberley (2008) | Hydrocharitaceae. | ICBN |
| Nakamurella | Frankiales | Tao et al. (2004); Ludwig et al. (2012) | . | ICNB |
| Nama | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Namacodon | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Namaquanthus | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Namataea | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Namhaeicola | Flavobacteriales | Jung et al. (2012) | . | ICNB |
| Namibia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Namibornis | Passeriformes | Clements (2007) | . | ICZN |
| Namiella | Phlebobranchia | Monniot & Monniot (1972) | Ascidiidae. | ICZN |
| Namophila | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Nanaloricus | Nanaloricida | Heiner & Kristensen (2009) | . | ICZN |
| Nananthea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nananthus | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Nancythalia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nandayus | Psittaciformes | Clements (2007) | . | ICZN |
| Nandina | Ranunculales | Mabberley (2008) | Berberidaceae. | ICBN |
| Nandinia | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Nanger | Artiodactyla | Grubb (2005) | . | ICZN |
| Nangura | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Nannochloris | Chlorellales | Somogyi et al. (2011); Neustupa et al. (2011) | As Nannochloris-like clade. | ICBN |
| Nannochloropsis | Eustigmatales | Hibberd (1981): Hegewald et al. (2007) | . | ICBN |
| Nannocoryne | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Nannocystis | Myxococcales | Garrity et al. (2005) | . | ICNB |
| Nannoeca | Acanthoecida | Leadbeater & Thomsen (2000) | . | ICZN |
| Nannoglottis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nannonemertes | Pelagica | Gibson (1995) | . | ICZN |
| Nannophrya | Haptorida | Lynn (2008) | . | ICZN |
| Nannophryne | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Nannophrys | Anura | Vitt & Caldwell (2009) | Dicroglossidae. | ICZN |
| Nannopsittaca | Psittaciformes | Clements (2007) | . | ICZN |
| Nannorrhops | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Nannoscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Nannosciurus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nannospalax | Rodentia | McKenna & Bell (1997); Musser & Carleton (2005) | Later synonym of Spalax. | ICZN |
| Nanochilus | Zingiberales | Mabberley (2008) | Zingiberaceae. | ICBN |
| Nanocnide | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Nanodea | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Nanofila | Cryptofilida | Bass et al. (2009) | . | ICZN |
| Nanognathia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Nanomarsupella | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nanomia | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Nanomitriella | Funariales | Goffinet et al. (2009) | . | ICBN |
| Nanomitriopsis | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Nanonycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nanopera | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nanophyton | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nanorana | Anura | Vitt & Caldwell (2009) | Dicroglossidae. | ICZN |
| Nanorrhinum | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Nanos | Pseudodendromonadales | Kim et al. (2009) | . | ICZN |
| Nanothamnus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nanothecium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Nanozostera | Alismatales | Mabberley (2008) | Zosteraceae. | ICBN |
| Napaea | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Napaeozapus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Napamichum | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Napeanthus | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Napoleonaea | Ericales | Mabberley (2008) | Lecythidaceae. | ICBN |
| Napothera | Passeriformes | Clements (2007) | . | ICZN |
| Naravelia | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Narcine | Torpediniformes | Nelson (2006) | . | ICZN |
| Narcissus | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Nardia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nardophyllum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nardostachys | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Narduroides | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Nardus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Narella | Alcyonacea | Bayer (1981) | Primnoidae. | ICZN |
| Nargedia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Naringi | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Narke | Torpediniformes | Nelson (2006) | . | ICZN |
| Narrabeeba | Dictyoceratida | Cook & Bergquist (2002) | . | ICZN |
| Narthecium | Dioscoreales | Mabberley (2008) | Nartheciaceae. | ICBN |
| Narudasia | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Narvalina | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nasa | Cornales | Mabberley (2008) | Loasaceae. | ICBN |
| Nasalis | Primates | McKenna & Bell (1997) | . | ICZN |
| Nashia | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Nasica | Passeriformes | Clements (2007) | . | ICZN |
| Nasikabatrachus | Anura | Vitt & Caldwell (2009) | Sooglossidae. | ICZN |
| Nasirana | Anura | Vitt & Caldwell (2009) | Ranidae. | ICZN |
| Nasolamia | Carcharhiniformes | Nelson (2006) | . | ICZN |
| Nassauvia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nassella | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Nassula | Nassulida | Lynn (2008) | . | ICZN |
| Nassulides | Nassulida | Lynn (2008) | . | ICZN |
| Nassulopsis | Synhymeniida | Lynn (2008) | Later synonym of Enneameron?. | ICZN |
| Nasturtiopsis | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Nasturtium | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Nastus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Nasua | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Nasuella | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Natalobatrachus | Anura | Vitt & Caldwell (2009) | Pyxicephalidae. | ICZN |
| Natalus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Natator | Testudinata | Vitt & Caldwell (2009) | Cheloniidae. | ICZN |
| Nathaliella | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Nathella | Clevelandellida | Lynn (2008) | nomen dubium. | ICZN |
| Natlandia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992); Özdikmen (2009) | Junior homonym. Substituted by Doyrana. | ICZN |
| Natonemertes | Pelagica | Gibson (1995) | . | ICZN |
| Natranaerobius | Natranaerobiales | Mesbah et al. (2007) | . | ICNB |
| Natranaerovirga | Clostridiales | Sorokin et al. (2012) | . | ICNB |
| Natrialba | Halobacteriales | Garrity et al. (2005) | . | ICNB |
| Natribacillus | Bacillales | Echigo et al. (2012) | . | ICNB |
| Natriciteres | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Natrinema | Halobacteriales | Garrity et al. (2005) | . | ICNB |
| Natrix | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Natroniella | Halanaerobiales | Garrity et al. (2005) | . | ICNB |
| Natronincola | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Natronoarchaeum | Halobacteriales | Shimane et al. (2010) | . | ICNB |
| Natronobacillus | Bacillales | Sorokin et al. (2008) | . | ICNB |
| Natronobacterium | Halobacteriales | Garrity et al. (2005) | . | ICNB |
| Natronocella | Chromatiales | Sorokin et al. (2007) | . | ICNB |
| Natronococcus | Halobacteriales | Garrity et al. (2005) | . | ICNB |
| Natronoflexus | Bacteroidales | Sorokin et al. (2011) | . | ICNB |
| Natronolimnobius | Halobacteriales | Itoh et al. (2005) | . | ICNB |
| Natronomonas | Halobacteriales | Garrity et al. (2005) | . | ICNB |
| Natronorubrum | Halobacteriales | Garrity et al. (2005) | . | ICNB |
| Natronovirga | Natranaerobiales | Mesbah & Wiegel (2009) | . | ICNB |
| Natsiatopsis | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Natsiatum | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Nauclea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Naucleopsis | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Naudinia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Naufraga | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Naultinus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Naumannella | Propionibacteriales | Rieser et al. (2012) | . | ICNB |
| Naumovia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Nauphantopsis | Coronatae | Kramp (1961) | . | ICZN |
| Nausithoe | Coronatae | Kramp (1961) | "Nausithoë". | ICZN |
| Nautactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Nautella | Rhodobacterales | Vandecandelaere et al. (2009) | . | ICNB |
| Nautilia | Nautiliales | Garrity et al. (2005); Miroshnichenko et al. (2004) | . | ICNB |
| Nautilocalyx | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Nautonia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Navarretia | Ericales | Mabberley (2008) | Polemoniaceae. | ICBN |
| Navia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Navisolenia | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Calciosoleniaceae. | ICBN |
| Naxella | Nassulida | Lynn (2008) | . | ICZN |
| Naxibacter | Burkholderiales | Xu et al. (2005); Kämpfer et al. (2011) | Later synonym of Massilia. | ICNB |
| Nayariophyton | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Neacomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Neafrapus | Apodiformes | Clements (2007) | . | ICZN |
| Nealchornea | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Neamblysomus | Afrosoricida | Bronner & Jenkins (2005) | . | ICZN |
| Neamphius | Hadromerida | Rützler (2002) | . | ICZN |
| Neanotis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neatostema | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Nebela | Arcellinida | Meisterfeld (2000) | Difflugina -- Nebelidae. | ICZN |
| Nebelia | Bruniales | Mabberley (2008) | Bruniaceae. | ICBN |
| Neblinaea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neblinantha | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Neblinanthera | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Neblinathamnus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nebrius | Orectolobiformes | Nelson (2006) | . | ICZN |
| Necepsia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Nechamandra | Alismatales | Mabberley (2008) | Hydrocharitaceae. | ICBN |
| Neckera | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neckeropsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Necopinatum | Parachela | Kinchin (1994) | . | ICZN |
| Necromys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Necropsobacter | Pasteurellales | Christensen et al. (2011) | . | ICNB |
| Necrosyrtes | Falconiformes | Clements (2007) | . | ICZN |
| Nectactis | Corallimorpharia | Fautin et al. (2007) | . | ICZN |
| Nectandra | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Nectarinia | Passeriformes | Clements (2007) | . | ICZN |
| Nectaropetalum | Malpighiales | Mabberley (2008) | Erythroxylaceae. | ICBN |
| Nectaroscilla | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Nectocaecilia | Gymnophiona | Vitt & Caldwell (2009) | Typhlonectidae. | ICZN |
| Nectodamas | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Nectogale | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Nectomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nectonema | Nectonematoidea | Schmidt-Rhaesa (2002); Brusca & Brusca (2003) | . | ICZN |
| Nectonemertes | Pelagica | Gibson (1995) | . | ICZN |
| Nectophryne | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Nectophrynoides | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Nectopyramis | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Nectouxia | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Necturus | Caudata | Vitt & Caldwell (2009) | Proteidae. | ICZN |
| Neea | Caryophyllales | Mabberley (2008) | Nyctaginaceae. | ICBN |
| Needhamiella | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Neeopsis | Caryophyllales | Mabberley (2008) | Nyctaginaceae. | ICBN |
| Neeragrostis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neesenbeckia | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Neesia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Neesiochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neesioscyphus | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Neevea | Stylonematales | Schneider & Wynne (2007) | . | ICBN |
| Negaprion | Carcharhiniformes | Nelson (2006) | . | ICZN |
| Negativicoccus | Selenomonadales | Marchandin et al. (2010) | . | ICNB |
| Negombata | Poecilosclerida | Kelly & Samaai (2002) | . | ICZN |
| Negombo | Halichondrida | Hooper (2002) | . | ICZN |
| Negria | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Neillia | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Neis | Beroida | Harbison & Madin (1982) | . | ICZN |
| Neisseria | Neisseriales | Garrity et al. (2005) | . | ICNB |
| Nelia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Nelliemelba | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nellocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Nellymyces | Rhipidiales | Dick (2001); Kirk et al. (2008) | Rhipidiaceae. | ICBN |
| Nelmesia | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Nelsia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nelsonia | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nelsonia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Nelsonianthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nelsonophryne | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Nelumbo | Proteales | Mabberley (2008) | Nelumbonaceae. | ICBN |
| Nemacaulis | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Nemacladus | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Nemactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Nemalecium | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Nemalion | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Nemalionopsis | Thoreales | Schneider & Wynne (2007) | . | ICBN |
| Nemamyxine | Myxiniformes | Nelson (2006) | . | ICZN |
| Nemanthus | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Nemastoma | Nemastomatales | Schneider & Wynne (2007) | . | ICBN |
| Nemastylis | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Nematanthus | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Nematochrysis | | Kristiansen & Preisig (2001) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. | ICBN |
| Nematochrysopsis | Sarcinochrysidales | Andersen & Preisig (2000) | . | ICBN |
| Nematocladia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Nematocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Nematodinium | Gymnodiniales | Fensome et al. (1993) | . | ICBN |
| Nematoides | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Nematolepis | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Nematophora | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nematophthora | Leptomitales | Dick (2001); Kirk et al. (2008) | Leptolegniellaceae. | ICBN |
| Nematoplaca | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Nematopoa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Nematopsides | Gymnodiniales | Fensome et al. (1993) | . | ICBN |
| Nematopsis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Nematopteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Nematosphaeropsis | Gonyaulacales | Fensome et al. (1993) | Holocene. | ICBN |
| Nematostelium | Protosteliales | Olive (1975) | . | ICBN |
| Nematostella | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Nematostylis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nemenzophyllia | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Nemertellina | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Nemertellopsis | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Nemertesia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Nemertinoides | Nemertodermatida | Sterrer (1998) | . | ICZN |
| Nemertobus | Pelagica | Gibson (1995); Kajihara et al. (2008) | Junior synonym of Obnemertes. | ICZN |
| Nemertoderma | Nemertodermatida | Sterrer (1998) | . | ICZN |
| Nemertopsella | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Nemertopsis | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Nemertoscolex | Heteronemertea | Kajihara et al. (2008) | . | ICZN |
| Nemesia | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Nemogullmia | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Nemophila | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Nemopsis | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Nemosenecio | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nemosia | Passeriformes | Clements (2007) | . | ICZN |
| Nemuaron | Laurales | Mabberley (2008) | Atherospermataceae. | ICBN |
| Nemum | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Nenax | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nenga | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Neoabbottiella | Cryptonemiales | Silva (2002); Schneider & Wynne (2007) | . | ICBN |
| Neoacanthocephaloides | Echinorhynchida | Amin (1985) | . | ICZN |
| Neoachmandra | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Neoagardhiella | Gigartinales | Schneider & Wynne (2007) | Later synonym of Agardhiella. | ICBN |
| Neoaiptasia | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Neoalsomitra | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Neoapaloxylon | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neoarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Neoarmaueria | Pelagica | Gibson (1995) | . | ICZN |
| Neoasaia | Rhodospirillales | Yukphan et al. (2006) | . | ICNB |
| Neoastelia | Asparagales | Mabberley (2008) | Asteliaceae. | ICBN |
| Neoaulaxinia | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Phymatellidae. | ICZN |
| Neoaulocystis | Lychniscosida | Reiswig (2002) | . | ICZN |
| Neobaclea | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Neobakuella | Urostylida | Li et al. (2011) | . | ICZN |
| Neobalanocarpus | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Neobarbella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neobassia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Neobathiea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neobatrachus | Anura | Vitt & Caldwell (2009) | Limnodynastidae. | ICZN |
| Neobeguea | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Neobennettia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neobenthamia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neobertiera | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neobipteria | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Neoblakea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neobodo | Neobodonida | Moreira et al. (2004) | . | ICZN |
| Neobolusia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neobouteloua | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neoboutonia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Neobracea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Neobrittonia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Neobryophyllum | Haptorida | Lynn (2008) | . | ICZN |
| Neobuccella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trichohyalidae. | ICZN |
| Neobuchia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Neobursaridium | Peniculida | Lynn (2008) | . | ICZN |
| Neobuxbaumia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Neobyrnesia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Neocabreria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neocallitropsis | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Neocarya | Malpighiales | Mabberley (2008) | Chrysobalanaceae. | ICBN |
| Neocassidulina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Fursenkoinidae. | ICZN |
| Neocatena | Astrorhizida | Kaminski (2000); Özdikmen (2009) | Baculellidae. Substitute name for Catena. | ICZN |
| Neocentema | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Neocentrophyes | Homalorhagida | Higgins (1990) | . | ICZN |
| Neoceratium | Gonyaulacales | Gómez et al. (2010); Calado & Huisman (2010); Gómez (2010) | Probably a junior synonym of Tripos. | ICBN |
| Neoceratodus | Ceratodontiformes | Nelson (2006) | . | ICZN |
| Neocercomonas | Cercomonadida | Ekelund et al. (2004); Karpov et al. (2006) | Juniour synonym of Cercomonas. | ICZN |
| Neochamaelea | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Neocheiropteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Neochelidon | Passeriformes | Clements (2007) | . | ICZN |
| Neochen | Anseriformes | Clements (2007) | . | ICZN |
| Neochevalierodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neochildia | Acoela | Hooge & Tyler (2005) | . | ICZN |
| Neochlamydia | Chlamydiales | Garrity et al. (2005) | . | ICNB |
| Neochmia | Passeriformes | Clements (2007) | . | ICZN |
| Neochordodes | Gordioidea | Schmidt-Rhaesa (2002); Poinar Jr. (2008) | . | ICZN |
| Neocichla | Passeriformes | Clements (2007) | . | ICZN |
| Neocinnamomum | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Neocladia | Poecilosclerida | Vacelet (2008) | . | ICZN |
| Neocogniauxia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neocollettia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neocondylactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Neoconorbina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rosalinidae. | ICZN |
| Neocossyphus | Passeriformes | Clements (2007) | . | ICZN |
| Neocouma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Neocrex | Gruiformes | Clements (2007) | . | ICZN |
| Neocrosbyia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Bagginidae. | ICZN |
| Neoctantes | Passeriformes | Clements (2007) | . | ICZN |
| Neocuatrecasia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neodasys | Chaetonotida | Hummon & Todaro (2010) | . | ICZN |
| Neodelosina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Delosinidae. | ICZN |
| Neodicladiella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neodillenia | Dilleniales | Mabberley (2008) | Dilleniaceae. | ICBN |
| Neodilsea | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Neodiscorbinella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Discorbidae. | ICZN |
| Neodistemon | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Neodistoma | Aplousobranchia | Kott (1998) | Holozoidae. | ICZN |
| Neodolichomitra | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neodon | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Neodrepanis | Passeriformes | Clements (2007) | . | ICZN |
| Neodriessenia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Neodryas | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neoechinorhynchus | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Neoemplectonema | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Neoeplingia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Neoeponides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Discorbidae. | ICZN |
| Neofabricia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Neofelis | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Neofiber | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Neofibularia | Poecilosclerida | Hajdu & Van Soest (2002) | . | ICZN |
| Neofranciella | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neogaerrhinum | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Neogallitellia | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992); Özdikmen (2009) | Guembelitriidae. Substitute name for Gallitellia. | ICZN |
| Neogardneria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neogastroclonium | Rhodymeniales | Wynne & Schneider (2010) | . | ICBN |
| Neogeneia | Stichotrichida | Lynn (2008) | . | ICZN |
| Neoglabratella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glabratellidae. | ICZN |
| Neoglaziovia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Neogloboquadrina | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Globorotaliidae. | ICZN |
| Neogoezia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Neogoniolithon | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Neogontscharovia | Caryophyllales | Mabberley (2008) | Plumbaginaceae. | ICBN |
| Neogossea | Chaetonotida | Balsamo et al. (2009) | . | ICZN |
| Neogrollea | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Neoguillauminia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Neohalcampa | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Neohalosacciocolax | Palmariales | Schneider & Wynne (2007) | . | ICBN |
| Neoharmsia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neoharriotta | Chimaeriformes | Nelson (2006) | . | ICZN |
| Neohemsleya | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Neohenneguya | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Neohenricia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Neoheteromita | Glissomonadida | Howe et al. (2009) | . | ICZN |
| Neohirmocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Neohodgsonia | Neohodgsoniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Neoholmesia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neohydromys | Rodentia | McKenna & Bell (1997); Musser & Carleton (2005) | Later synonym of Pseudohydromys. | ICZN |
| Neohylomys | Erinaceomorpha | Hutterer (2005) | . | ICZN |
| Neohypnella | Hookeriales | Goffinet et al. (2009) | . | ICBN |
| Neohypophyllum | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neoichthyophthirius | Ophryoglenida | Lynn (2008) | . | ICZN |
| Neoizziella | Nemaliales | Lin et al. (2011) | . | ICBN |
| Neojeffreya | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neojobertia | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Neokeronopsis | Sporadotrichida | Lynn (2008) | . | ICZN |
| Neokomagataea | Rhodospirillales | Yukphan et al. (2011) | . | ICNB |
| Neolacunisoma | Polymorphida | Amin & Canaris (1997) | Centrorhynchidae. | ICZN |
| Neolalage | Passeriformes | Clements (2007) | . | ICZN |
| Neolamarckia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neolaugeria | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neolemonniera | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Neolenticulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Neolepisorus | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Neolestes | Passeriformes | Clements (2007) | . | ICZN |
| Neolindbergia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neolineus | Heteronemertea | Gibson (1995) | . | ICZN |
| Neolingulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nodosariidae. | ICZN |
| Neolitsea | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Neolloydia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Neololeba | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neoluederitzia | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Neomacounia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neomarica | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Neomecynostomum | Acoela | Faubel & Noreña (2001) | . | ICZN |
| Neomeesia | Splachnales | Goffinet et al. (2009) | . | ICBN |
| Neomezia | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Neomicrocalamus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neomillspaughia | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Neomirandea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neomixis | Passeriformes | Clements (2007) | . | ICZN |
| Neomonocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Neomoorea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neomorphus | Cuculiformes | Clements (2007) | . | ICZN |
| Neomortonia | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Neomussaenda | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neomyrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Neomys | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Neomyxine | Myxiniformes | Nelson (2006) | . | ICZN |
| Neomyxobolus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Neonauclea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neoncicola | Oligacanthorhynchida | Amin (1985) | . | ICZN |
| Neonelsonia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Neonema | Tribonematales | Ettl (1978) | . | ICBN |
| Neonesomia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neonicholsonia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Neonoguchia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neonosemoides | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Neonotonia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neonycteris | Chiroptera | Simmons (2005) | . | ICZN |
| Neonyctotherus | Clevelandellida | Lynn (2008) | . | ICZN |
| Neoorthocaulis | Jungermanniales | Söderström et al. (2010) | . | ICBN |
| Neopallasia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neoparacondylactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Neoparamoeba | Dactylopodida | Rogerson & Patterson (2000); Smirnov et al. (2005) | . | ICZN |
| Neoparrya | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Neoparvicapsula | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Neopateoris | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Neopelma | Passeriformes | Clements (2007) | . | ICZN |
| Neopelta | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Neopeltidae. | ICZN |
| Neopentanisia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neoperezia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Neopetrosia | Haplosclerida | Desqueyroux-Faúndez & Valentine (2002) | . | ICZN |
| Neophascogale | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Neophema | Psittaciformes | Clements (2007) | . | ICZN |
| Neophoca | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Neophocaena | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Neophoenix | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Neophrissospongia | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Corallistidae. | ICZN |
| Neophron | Falconiformes | Clements (2007) | . | ICZN |
| Neopileolus | Euglyphida | Meisterfeld (2000); Özdikmen (2009) | Substitute name for Pileolus. | ICZN |
| Neopipo | Passeriformes | Clements (2007) | . | ICZN |
| Neopodospongia | Poecilosclerida | Sim-Smith & Kelly (2011) | . | ICZN |
| Neopotamolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Neopringlea | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Neopsittacus | Psittaciformes | Clements (2007) | . | ICZN |
| Neopteryx | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Neoptilota | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neoptychocarpus | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Neoraimondia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Neoraja | Rajiformes | Nelson (2006) | . | ICZN |
| Neoraputia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Neorautanenia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neoregelia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Neoregnellia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Neorhadinorhynchus | Echinorhynchida | Amin (1985); Pichelin & Cribb (2001) | Junior synonym of Diplosentis. | ICZN |
| Neorhodella | Dixoniellales | Yokoyama et al. (2009) | . | ICBN |
| Neorhodomela | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neorhopias | Passeriformes | Clements (2007) | . | ICZN |
| Neorickettsia | Rickettsiales | Garrity et al. (2005) | . | ICNB |
| Neorites | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Neoroepera | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Neoromicia | Chiroptera | Simmons (2005) | . | ICZN |
| Neorudolphia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neorutenbergia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Neoschmidia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Neoschneideria | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Neoschrammeniella | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Corallistidae. | ICZN |
| Neoschumannia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Neosciadium | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Neoscortechinia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Neosemantis | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Neosepicaea | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Neosharpiella | Bartramiales | Goffinet et al. (2009) | . | ICBN |
| Neoshirakia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Neosiphonia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neosiphonia | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Phymatellidae. | ICZN |
| Neositta | Passeriformes | Clements (2007) | . | ICZN |
| Neosparton | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Neospiroloculina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spiroloculinidae. | ICZN |
| Neospiza | Passeriformes | Clements (2007) | . | ICZN |
| Neospongodes | Alcyonacea | Bayer (1981) | Nephtheidae. | ICZN |
| Neospora | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Neosprucea | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Neostapfia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neostapfiella | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neostenanthera | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Neostrearia | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Neostygarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Neotatea | Malpighiales | Mabberley (2008) | Bonnetiaceae. | ICBN |
| Neotenophycus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neotessmannia | Malvales | Mabberley (2008) | Muntingiaceae. | ICBN |
| Neotetracus | Erinaceomorpha | Hutterer (2005) | . | ICZN |
| Neothelohanellus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Neothorelia | Brassicales | Mabberley (2008) | Resedaceae. | ICBN |
| Neothraupis | Passeriformes | Clements (2007) | . | ICZN |
| Neotima | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Neotina | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Neotinea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neotis | Gruiformes | Clements (2007) | . | ICZN |
| Neotoma | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Neotomodon | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Neotomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Neotorularia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Neotragus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Neotrichocolea | Ptilidiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Neottia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neottianthe | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Neoturczaninowia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Neoturris | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Neotysonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neouvaria | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Neouvigerina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Uvigerinidae. | ICZN |
| Neovahlkampfia | Schizopyrenida | Brown & De Jonckheere (1999) | . | ICZN |
| Neoveitchia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Neovison | Carnivora | Wozencraft (2005) | . | ICZN |
| Neowerdermannia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Neoxolmis | Passeriformes | Clements (2007) | . | ICZN |
| Neozoanthus | Zoanthidea | Sinniger et al. (2005) | . | ICZN |
| Nepenthes | Caryophyllales | Mabberley (2008) | Nepenthaceae. | ICBN |
| Nepeta | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Nephelaphyllum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nephelium | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Nephelochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Nephelolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nephelornis | Passeriformes | Clements (2007) | . | ICZN |
| Nephopteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Nephradenia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Nephrangis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nephridiorhynchus | Oligacanthorhynchida | Amin (1985) | . | ICZN |
| Nephrochloris | Chloramoebales | Ettl (1978) | . | ICBN |
| Nephrococcus | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Nephrodesmus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Nephrodiella | Mischococcales | Ettl (1978) | . | ICBN |
| Nephroisospora | Eucoccidiorida | Wünschmann et al. (2010) | . | ICZN |
| Nephrolepis | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Nephromyces | | Cavalier-Smith (1996/7); Saffo et al. (2010) | Phylum Apicomplexa (phylogenetically within class Coccidea; order Piroplasmorida). | ICZN |
| Nephrophyllidium | Asterales | Mabberley (2008) | Menyanthaceae. | ICBN |
| Nephrophyllum | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Nephroselmis | Nephroselmidales | Nakayama et al. (2007) | . | ICBN |
| Nephrosperma | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Nephrospyis | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Nephrotheca | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nephrurus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Nephthea | Alcyonacea | Bayer (1981) | Nephtheidae. | ICZN |
| Nephtheis | Aplousobranchia | Kott (1998) | Clavellidae. | ICZN |
| Nephthyigorgia | Alcyonacea | Williams (2000) | Nidaliidae. | ICZN |
| Nephthytis | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Nepsera | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Neptunia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neptuniibacter | Oceanospirillales | Arahal et al. (2007) | . | ICNB |
| Neptunomonas | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Nerada | Pseudodendromonadales | Cavalier-Smith & Chao (2006) | . | ICZN |
| Neraudia | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Nereida | Rhodobacterales | Pujalte et al. (2005) | . | ICNB |
| Nereoginkgo | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Neriacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Nerine | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Nerisyrenia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Nerium | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Nernstia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nerodia | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Nervilia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nesaea | Myrtales | Mabberley (2008) | Lythraceae. | ICBN |
| Nesampelos | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nesasio | Strigiformes | Clements (2007) | . | ICZN |
| Nesillas | Passeriformes | Clements (2007) | . | ICZN |
| Nesiota | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Nesiotites | Soricomorpha | Hutterer (2005) | Recently extinct. | ICZN |
| Nesiotobacter | Rhodobacterales | Donachie et al. (2006) | . | ICNB |
| Neslia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Nesocaryum | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Nesocharis | Passeriformes | Clements (2007) | . | ICZN |
| Nesocichla | Passeriformes | Clements (2007) | . | ICZN |
| Nesoclopeus | Gruiformes | Clements (2007) | . | ICZN |
| Nesocodon | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Nesoctites | Piciformes | Clements (2007) | . | ICZN |
| Nesoenas | Columbiformes | Clements (2007) | . | ICZN |
| Nesofregetta | Procellariiformes | Clements (2007) | . | ICZN |
| Nesogenes | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Nesogordonia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Nesohedyotis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nesokia | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nesolagus | Lagomorpha | McKenna & Bell (1997) | . | ICZN |
| Nesolindsaea | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Nesoluma | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Nesomia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nesomimus | Passeriformes | Clements (2007) | . | ICZN |
| Nesomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nesophila | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Nesophontes | Soricomorpha | Hutterer (2005) | Recently extinct. | ICZN |
| Nesopsar | Passeriformes | Clements (2007) | . | ICZN |
| Nesoromys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Nesoryzomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nesoscaptor | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001); Hutterer (2005) | Later synonym of Mogera. | ICZN |
| Nesospingus | Passeriformes | Clements (2007) | . | ICZN |
| Nesospiza | Passeriformes | Clements (2007) | . | ICZN |
| Nesotriccus | Passeriformes | Clements (2007) | . | ICZN |
| Nesphostylis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Nessia | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Nestegis | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Nesterenkonia | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Nestlera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nestor | Psittaciformes | Clements (2007) | . | ICZN |
| Nestotus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Netocertoides | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Netrium | Zygnematales | Gontcharov (2008) | . | ICBN |
| Netrostoma | Rhizostomeae | Kramp (1961) | . | ICZN |
| Netta | Anseriformes | Clements (2007) | . | ICZN |
| Nettapus | Anseriformes | Clements (2007) | . | ICZN |
| Netzelia | Arcellinida | Meisterfeld (2000) | Difflugina -- Lesquereusiidae. | ICZN |
| Neuburgia | Gentianales | Mabberley (2008) | Loganiaceae. | ICBN |
| Neuontobotrys | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Neuracanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Neurachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neurada | Malvales | Mabberley (2008) | Neuradaceae. | ICBN |
| Neuradopsis | Malvales | Mabberley (2008) | Neuradaceae. | ICBN |
| Neurergus | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Neurocalyx | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Neurocaulon | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Neuroglossum | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neurolaena | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neurolakis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Neurolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Neurolepis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neuronemertes | Pelagica | Gibson (1995) | . | ICZN |
| Neuropeltis | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Neuropeltopsis | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Neuropoa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Neurotheca | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Neurotrichus | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Neurymenia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Neusticomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Neusticurus | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Neuwiedia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nevada | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Nevadne | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Nevillea | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Nevillina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Neviusia | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Nevskia | Xanthomonadales | Garrity et al. (2005) | . | ICNB |
| Newbouldia | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Newbya | Saprolegniales | Kirk et al. (2008) | Saprolegniaceae. | ICBN |
| Newcastelia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Newtonia | Passeriformes | Clements (2007) | . | ICZN |
| Newtonia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Neyraudia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Nezahualcoyotlia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Niabella | Sphingobacteriales | Kim et al. (2007) | . | ICNB |
| Niastella | Sphingobacteriales | Weon et al. (2006) | . | ICNB |
| Nicandra | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Nicator | Passeriformes | Clements (2007) | . | ICZN |
| Nicaule | Alcyonacea | Bayer (1981) | Plexauridae. | ICZN |
| Nicella | Alcyonacea | Bayer (1981); Bayer & Grasshoff (1994) | Ellisellidae. | ICZN |
| Nichallea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nicobariodendron | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Nicodemia | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Nicolasia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nicoletella | Pasteurellales | Kuhnert et al. (2004) | . | ICNB |
| Nicoliana | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Nicollella | Vestibuliferida | Lynn (2008) | . | ICZN |
| Nicolletia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nicotiana | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Nidalia | Alcyonacea | Bayer (1981) | Nidaliidae. | ICZN |
| Nidaliopsis | Alcyonacea | Bayer (1981); Williams (2000) | Nidaliidae. | ICZN |
| Nidema | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nidorella | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nidularium | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Niemarshallia | Tintinnida | Lynn (2008) | . | ICZN |
| Niemeyera | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Nienburgella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nienburgia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nierembergia | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Nietneria | Dioscoreales | Mabberley (2008) | Nartheciaceae. | ICBN |
| Nigella | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Nigrita | Passeriformes | Clements (2007) | . | ICZN |
| Nilaus | Passeriformes | Clements (2007) | . | ICZN |
| Nilopegamys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nilssonia | Testudinata | Vitt & Caldwell (2009) | Trionychidae. | ICZN |
| Niltava | Passeriformes | Clements (2007) | . | ICZN |
| Nimbaphrynoides | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Ningaui | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Ninia | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Ninox | Strigiformes | Clements (2007) | . | ICZN |
| Niobia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Niphaea | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Niphates | Haplosclerida | Desqueyroux-Faúndez & Valentine (2002) | . | ICZN |
| Niphidium | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Niphogeton | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Niphotrichum | Grimmiales | Goffinet et al. (2009) | . | ICBN |
| Nipponanthemum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nipponarcon | Exogenida | Lynn (2008) | . | ICZN |
| Nipponia | Ciconiiformes | Clements (2007) | . | ICZN |
| Nipponnemertes | Cratenemertea | Gibson (1995); Crandall & Gibson (1998) | . | ICZN |
| Nipponolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nipponomicrura | Heteronemertea | Kajihara et al. (2008) | . | ICZN |
| Nirarathamnos | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Nisaea | Rhodospirillales | Urios et al. (2008) | . | ICNB |
| Niscometes | Evaginogenida | Lynn (2008) | . | ICZN |
| Nissolia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Nitella | Charales | McCourt et al. (1999) | . | ICBN |
| Nitellopsis | Charales | McCourt et al. (1999) | . | ICBN |
| Nitophyllum | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nitospinosa | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nitraria | Sapindales | Mabberley (2008) | Nitrariaceae. | ICBN |
| Nitratifractor | Campylobacterales | Nakagawa et al. (2005) | . | ICNB |
| Nitratireductor | Rhizobiales | Labbé et al. (2004) | . | ICNB |
| Nitratiruptor | Campylobacterales | Nakagawa et al. (2005) | . | ICNB |
| Nitriliruptor | Nitriliruptorales | Sorokin et al. (2009); Ludwig et al. (2012) | . | ICNB |
| Nitrincola | Oceanospirillales | Dimitriu et al. (2005) | . | ICNB |
| Nitritalea | Cytophagales | Anil Kumar et al. (2010); Ludwig et al. (2011) | . | ICNB |
| Nitrobacter | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Nitrococcus | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Nitrophila | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nitrosococcus | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Nitrosolobus | Nitrosomonadales | Garrity et al. (2005) | . | ICNB |
| Nitrosomonas | Nitrosomonadales | Garrity et al. (2005) | . | ICNB |
| Nitrosospira | Nitrosomonadales | Garrity et al. (2005) | . | ICNB |
| Nitrospina | Desulfobacterales | Garrity et al. (2005) | . | ICNB |
| Nitrospira | Nitrospirales | Garrity et al. (2005) | . | ICNB |
| Nivaliella | Colpodida | Lynn (2008) | . | ICZN |
| Nivellea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nivenia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Niveoscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Niviventer | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nizymenia | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Njinella | Astomatida | Lynn (2008) | . | ICZN |
| Noaea | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Noahdendron | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Noblea | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Nobregaea | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Nocardia | Corynebacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Nocardioides | Propionibacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Nocardiopsis | Streptosporangiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Noccaea | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Noctilio | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Noctiluca | Noctilucales | Fensome et al. (1993) | . | ICBN |
| Nodellum | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Nodobaculariella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Fischerinidae. | ICZN |
| Nodocapitus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Nodocarpaea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Nodogenerina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Stilostomellidae. | ICZN |
| Nodonema | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Nodophthalmidium | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nubeculariidae. | ICZN |
| Nodosarella | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Pleurostomellidae. | ICZN |
| Nodosaria | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nodosariidae. | ICZN |
| Nodosilinea | Pseudanabaenales | Perkerson III et al. (2011) | . | ICBN |
| Nodosinum | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hormosinidae. | ICZN |
| Nodularia | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Nodulina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hormosinidae. | ICZN |
| Nogra | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Noguchiodendron | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Noisettia | Malpighiales | Mabberley (2008) | Violaceae. | ICBN |
| Nolaclusilis | Tintinnida | Lynn (2008) | . | ICZN |
| Nolana | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Nolandella | Nolandida | Rogerson & Patterson (2000); Smirnov et al. (2005) | . | ICZN |
| Nolandia | Prorodontida | Foissner et al. (2008) | Colepidae. | ICZN |
| Nolina | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Nolleria | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nolletia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Noltea | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Nomascus | Primates | Groves (2005) | . | ICZN |
| Nomlandia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Nomocharis | Liliales | Mabberley (2008) | Liliaceae. | ICBN |
| Nomonyx | Anseriformes | Clements (2007) | . | ICZN |
| Nomosa | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Nonea | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Nonion | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nonionidae. | ICZN |
| Nonionella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nonionidae. | ICZN |
| Nonionellina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nonionidae. | ICZN |
| Nonionoides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nonionidae. | ICZN |
| Nonlabens | Flavobacteriales | Lau et al. (2005) | . | ICNB |
| Nonnula | Galbuliformes | Clements (2007) | . | ICZN |
| Nonomuraea | Streptosporangiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Nopalea | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Norantea | Ericales | Mabberley (2008) | Marcgraviaceae. | ICBN |
| Nordenstamia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Norlevinea | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Norlindhia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Normanbya | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Normandiodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Normanina | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Komokiidae. | ICZN |
| Noronhia | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Noronhomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Norrisia | Gentianales | Mabberley (2008) | Loganiaceae. | ICBN |
| Norrisiella | Chlorarachniales | Ota et al. (2007) | . | ICBN |
| Norrissia | Cryptonemiales | Silva (2002); Schneider & Wynne (2007) | . | ICBN |
| Northia | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Northiella | Psittaciformes | Clements (2007) | . | ICZN |
| Nosema | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nosemoides | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nosocomiicoccus | Bacillales | Alves et al. (2008) | . | ICNB |
| Nostoc | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Nostochopsis | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Nostocoidia | Micrococcales | Garrity et al. (2005); Kämpfer & Groth (2012) | Misspelling of "Candidatus Nostocoida", which is a later synonym of Tetrasphaera. | ICNB |
| Nostolachma | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Notaden | Anura | Vitt & Caldwell (2009) | Limnodynastidae. | ICZN |
| Notanthera | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Notechidnopsis | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Notechis | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Notelaea | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Noteochordodes | Gordioidea | Schmidt-Rhaesa (2002); Poinar Jr. (2008) | . | ICZN |
| Noteonemertes | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Neesidae. | ICZN |
| Noteroclada | Pelliales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nothapodytes | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Notharchus | Galbuliformes | Clements (2007) | . | ICZN |
| Notheria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nothoalsomitra | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Nothobaccaurea | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Nothobaccharis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nothobachia | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Nothobartsia | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Nothocalais | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nothocercus | Tinamiformes | Clements (2007) | . | ICZN |
| Nothoceros | Dendrocerotales | Renzaglia et al. (2009) | . | ICBN |
| Nothocestrum | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Nothochelone | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Nothochilus | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Nothocladus | Batrachospermales | Schneider & Wynne (2007) | . | ICBN |
| Nothocnide | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Nothocrax | Galliformes | Clements (2007) | . | ICZN |
| Nothodoritis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nothofagus | Fagales | Mabberley (2008) | Nothofagaceae. | ICBN |
| Nothogenia | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Nothogymnomitrion | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nothoholosticha | Urostylida | Li et al. (2009) | . | ICZN |
| Notholaena | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Notholca | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Notholirion | Liliales | Mabberley (2008) | Liliaceae. | ICBN |
| Nothopegia | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Nothophryne | Anura | Vitt & Caldwell (2009) | Pyxicephalidae. | ICZN |
| Nothoprocta | Tinamiformes | Clements (2007) | . | ICZN |
| Nothopsis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Nothosaerva | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nothoscordum | Asparagales | Mabberley (2008) | Alliaceae. | ICBN |
| Nothosmyrnium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Nothospondias | Sapindales | Mabberley (2008) | Simaroubaceae. | ICBN |
| Nothostele | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nothostrepta | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nothotsuga | Pinales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Nothura | Tinamiformes | Clements (2007) | . | ICZN |
| Noticastrum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Notila | Oxymonadida | Brugerolle & Lee (2000) | . | ICZN |
| Notiochelidon | Passeriformes | Clements (2007) | . | ICZN |
| Notiomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Notiomystis | Passeriformes | Clements (2007) | . | ICZN |
| Notiosciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Notiosorex | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Notobasis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Notocelis | Acoela | Dörjes (1968); Faubel & Noreña (2001) | . | ICZN |
| Notocephalus | Urostylida | Lynn (2008) | . | ICZN |
| Notoceras | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Notochaete | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Notochelys | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Notochloe | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Notocyathus | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Notodanthonia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Notodendrodes | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Notodendrodidae. | ICZN |
| Notogaeanemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Notohymena | Sporadotrichida | Lynn (2008) | . | ICZN |
| Notoligotrichum | Polytrichales | Goffinet et al. (2009) | . | ICBN |
| Notommata | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Notomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Notomyxine | Myxiniformes | Nelson (2006) | . | ICZN |
| Notophthalmus | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Notophycus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Notophyllia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Notopleura | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Notopora | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Notopteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Notopterygium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Notoraja | Rajiformes | Nelson (2006) | . | ICZN |
| Notorotalia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Elphidiidae. | ICZN |
| Notoryctes | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Notorynchus | Hexanchiformes | Nelson (2006) | . | ICZN |
| Notoscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Notoscyphus | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Notoseris | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Notosolenus | Sphenomonadales | Leedale (1967); Leedale (2000) | . | ICBN |
| Notospermus | Heteronemertea | Gibson (1995) | . | ICZN |
| Notothixos | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Notothlaspi | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Notothylas | Notothyladales | Renzaglia et al. (2009) | . | ICBN |
| Nototriche | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Nototrichium | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nototriton | Caudata | Vitt & Caldwell (2009) | Plethodontidae. | ICZN |
| Notoxoma | Colpodida | Lynn (2008); Bourland et al. (2011) | . | ICZN |
| Notylia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Notyliopsis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Nouelia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Nouria | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nouriidae. | ICZN |
| Novechiniscus | Echiniscoidea | Kinchin (1994) | . | ICZN |
| Novenia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Novispirillum | Rhodospirillales | Yoon et al. (2007) | . | ICNB |
| Novistrombidium | Strombidiida | Lynn (2008) | . | ICZN |
| Novoeumeces | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Novosigmella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992); Özdikmen (2009) | Hauerinidae. Substitute name for Sigmella. | ICZN |
| Novosphingobium | Sphingomonadales | Garrity et al. (2005) | . | ICNB |
| Novotelnova | Peronosporales | Kirk et al. (2008) | Peronosporaceae. | ICBN |
| Nowellia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Nowickea | Caryophyllales | Mabberley (2008) | Phytolaccaceae. | ICBN |
| Nuarchus | Limnomedusae | Bouillon et al. (2006) | . | ICZN |
| Nubecularia | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nubeculariidae. | ICZN |
| Nubeculariella | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rhabdamminidae. | ICZN |
| Nubeculina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nubeculariidae. | ICZN |
| Nubeculinita | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nubeculariidae. | ICZN |
| Nubeculopsis | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nubeculariidae. | ICZN |
| Nubenocephalus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Nubiella | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Nubsella | Sphingobacteriales | Asker et al. (2008) | . | ICNB |
| Nuchterleinella | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Nucifraga | Passeriformes | Clements (2007) | . | ICZN |
| Nuclearia | Nucleariida | Cavalier-Smith (1998) | . | ICZN |
| Nucleocorbula | Thigmotrichida | Lynn (2008) | . | ICZN |
| Nucleospora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nucleotaenium | Zygnematales | Gontcharov & Melkonian (2010) | . | ICBN |
| Nucleotethya | Hadromerida | Sarà (2002) | . | ICZN |
| Nucras | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Nucularia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nudiamphisiella | Stichotrichida | Lynn (2008) | . | ICZN |
| Nudifila | | Howe et al. (2011) | Domain Eucarya - Phylum Cercozoa - Class Imbricatea. | ICZN |
| Nudispora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Nuditheca | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Nudospongilla | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Numenius | Charadriiformes | Clements (2007) | . | ICZN |
| Numida | Galliformes | Clements (2007) | . | ICZN |
| Nummoloculina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Nummulites | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nummulitidae. | ICZN |
| Nummulopyrgo | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spiroloculinidae. | ICZN |
| Nuphar | Nymphaeales | Mabberley (2008) | Nymphaeaceae. | ICBN |
| Nuttallanthus | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Nuttallides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Epistomariidae. | ICZN |
| Nuxia | Lamiales | Mabberley (2008) | Stilbaceae. | ICBN |
| Nuytsia | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Nwynea | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Nyctaginia | Caryophyllales | Mabberley (2008) | Nyctaginaceae. | ICBN |
| Nyctalus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nyctanassa | Ciconiiformes | Clements (2007) | . | ICZN |
| Nyctanolis | Caudata | Vitt & Caldwell (2009) | Plethodontidae. | ICZN |
| Nyctanthes | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Nyctereutes | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Nycteria | Haemospororida | Perkins et al. (2000) | . | ICZN |
| Nycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nyctibates | Anura | Vitt & Caldwell (2009) | Arthroleptidae. | ICZN |
| Nyctibatrachus | Anura | Vitt & Caldwell (2009) | Nyctibatrachidae. | ICZN |
| Nyctibius | Caprimulgiformes | Clements (2007) | . | ICZN |
| Nycticalanthus | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Nycticebus | Primates | McKenna & Bell (1997) | . | ICZN |
| Nycticeinops | Chiroptera | Simmons (2005) | . | ICZN |
| Nycticeius | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nycticorax | Ciconiiformes | Clements (2007) | . | ICZN |
| Nyctidromus | Caprimulgiformes | Clements (2007) | . | ICZN |
| Nyctiellus | Chiroptera | Simmons (2005) | . | ICZN |
| Nyctimantis | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Nyctimene | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nyctinomops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nyctiphrynus | Caprimulgiformes | Clements (2007) | . | ICZN |
| Nyctiprogne | Caprimulgiformes | Clements (2007) | . | ICZN |
| Nyctixalus | Anura | Vitt & Caldwell (2009) | Rhacophoridae. | ICZN |
| Nyctocalos | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Nyctomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Nyctophilus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Nyctositum | Clevelandellida | Lynn (2008) | . | ICZN |
| Nyctotheroides | Clevelandellida | Lynn (2008) | . | ICZN |
| Nyctotherus | Clevelandellida | Lynn (2008) | . | ICZN |
| Nyctyornis | Coraciiformes | Clements (2007) | . | ICZN |
| Nyholmiella | Orthotrichales | Sawicki et al. (2010) | . | ICBN |
| Nymania | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Nymphaea | Nymphaeales | Mabberley (2008) | Nymphaeaceae. | ICBN |
| Nymphargus | Anura | Vitt & Caldwell (2009) | Centrolenidae. | ICZN |
| Nymphicus | Psittaciformes | Clements (2007) | . | ICZN |
| Nymphoides | Asterales | Mabberley (2008) | Menyanthaceae. | ICBN |
| Nypa | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Nyssa | Cornales | Mabberley (2008) | Nyssaceae. | ICBN |
| Nyssanthes | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Nystalus | Galbuliformes | Clements (2007) | . | ICZN |
| O | |
| Obelia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Oberonia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Obertrumia | Nassulida | Lynn (2008) | . | ICZN |
| Obesumbacterium | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Obetia | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Oblea | Peridiniales | Fensome et al. (1993) | . | ICBN |
| Obliquilingulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glandulinidae. | ICZN |
| Obliquostoma | Haptorida | Lynn (2008) | Junior homonym. | ICZN |
| Oblivia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oblongichytrium | Thraustochytriales | Yokoyama & Honda (2007) | . | ICBN |
| Obnemertes | Pelagica | Gibson (1995) | . | ICZN |
| Obolaria | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Obregonia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Obtegomaria | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Obtusifolium | Jungermanniales | Vilnet et al. (2008) | . | ICBN |
| Obuergeria | Eumonostilifera | Gibson (1995); Chernyshev (2003) | Obürgeria. | ICZN |
| Obvallatus | Eucoccidiorida | Perkins et al. (2000); Özdikmen (2009) | Substitute name for Adelina. | ICZN |
| Ocadia | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Occidozyga | Anura | Vitt & Caldwell (2009) | Dicroglossidae. | ICZN |
| Occiperipatoides | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Occultammina | Psamminida | Gooday & Tendal (2000) | . | ICZN |
| Oceanactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Oceanapia | Haplosclerida | Desqueyroux-Faúndez & Valentine (2002) | . | ICZN |
| Oceania | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Oceanibaculum | Rhodospirillales | Lai et al. (2009) | . | ICNB |
| Oceanibulbus | Rhodobacterales | Wagner-Döbler, I. et al. (2004) | . | ICNB |
| Oceanicaulis | | Strömpl, C. et al. (2003); Williams et al. (2007) | Domain Bacteria - Phylum Proteobacteria - Class Alphaproteobacteria. Hyphomonadaceae. | ICNB |
| Oceanicella | Rhodobacterales | Albuquerque et al. (2012) | . | ICNB |
| Oceanicola | Rhodobacterales | Cho & Giovannoni (2004) | . | ICNB |
| Oceanimonas | Aeromonadales | Garrity et al. (2005) | . | ICNB |
| Oceaniserpentilla | Oceanospirillales | Schlösser et al. (2008) | . | ICNB |
| Oceanisphaera | Aeromonadales | Romanenko et al. (2003) | . | ICNB |
| Oceanitalea | Micrococcales | Fu et al. (2012) | . | ICNB |
| Oceanites | Procellariiformes | Clements (2007) | . | ICZN |
| Oceanithermus | Thermales | Garrity et al. (2005) | . | ICNB |
| Oceanobacillus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Oceanobacter | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Oceanodroma | Procellariiformes | Clements (2007) | . | ICZN |
| Oceanospirillum | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Oceanotoga | Thermotogales | Jayasinghearachchi & Lal (2011) | . | ICNB |
| Ochagavia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Ochanostachys | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Ochetophila | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Ochetorhynchus | Passeriformes | Clements (2007) | . | ICZN |
| Ochiobryum | Bryales | Goffinet et al. (2009) | . | ICBN |
| Ochlandra | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ochmapexus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Ochna | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Ochoterenaea | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Ochoterenaia | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Ochotona | Lagomorpha | McKenna & Bell (1997) | . | ICZN |
| Ochotonophila | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Ochradenus | Brassicales | Mabberley (2008) | Resedaceae. | ICBN |
| Ochreinauclea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Ochridanus | Astomatida | Lynn (2008) | . | ICZN |
| Ochridaspongia | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Ochrobactrum | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Ochrobryum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Ochrocephala | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ochroma | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Ochromonas | Ochromonadales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Chromulinaceae (biflagellate). | ICBN |
| Ochrosia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Ochrosperma | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Ochrosphaera | Coccolithales | Jordan et al. (2004) | Hymenomonadaceae. | ICBN |
| Ochrostylon | Ochromonadales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Chromulinaceae (biflagellate). | ICBN |
| Ochrotomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Ochthephilus | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Ochthocharis | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Ochthochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ochthocosmus | Malpighiales | Mabberley (2008) | Ixonanthaceae. | ICBN |
| Ochthodium | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Ochthoeca | Passeriformes | Clements (2007) | . | ICZN |
| Ochthornis | Passeriformes | Clements (2007) | . | ICZN |
| Ochtodes | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Ochyraea | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Ocimum | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Oclemena | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ocotea | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Ocreatus | Apodiformes | Clements (2007) | . | ICZN |
| Octacanthium | Desmidiales | Gerrath (2003) | . | ICBN |
| Octacnemus | Phlebobranchia | Monniot & Monniot (1972); Monniot (2001) | Octacnemidae. | ICZN |
| Octadecabacter | Rhodobacterales | Garrity et al. (2005) | . | ICNB |
| Octamyrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Octarrhena | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Octineon | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Octoblepharum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Octobulbacea | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Octocanna | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Octocannoides | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Octoceras | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Octocirrus | Sporadotrichida | Lynn (2008) | nomen dubium. | ICZN |
| Octodendron | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Octodon | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Octodontomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Octogonade | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Octoknema | Santalales | Mabberley (2008) | Erythropalaceae. | ICBN |
| Octolepis | Malvales | Mabberley (2008) | Thymelaeaceae. | ICBN |
| Octolobus | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Octomeles | Cucurbitales | Mabberley (2008) | Datiscaceae. | ICBN |
| Octomeria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Octomitus | Diplomonadida | Brugerolle & Lee (2000) | . | ICZN |
| Octomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Octomyxa | Plasmodiophorida | Cavalier-Smith (1993); Kirk et al. (2008) | . | ICZN |
| Octophellia | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Octophialucium | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Octopoma | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Octopyle | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Octorathkea | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Octospina | Multivalvulida | Lom & Dyková (2006) | . | ICZN |
| Octospinifer | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Octospiniferoides | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Octosporea | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Octosporella | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Octotetraspora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Octotiara | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Octotrocha | Flosculariaceae | Segers (2002); Segers (2007) | . | ICZN |
| Octotropis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oculina | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Oculinaria | Stolidobranchia | Monniot & Monniot (1972) | Styelidae. | ICZN |
| Oculocincta | Passeriformes | Clements (2007) | . | ICZN |
| Oculosagitta | Aphragmophora | Bieri (1991) | Sagittidae. | ICZN |
| Oculosiphon | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rhabdamminidae. | ICZN |
| Ocyalus | Passeriformes | Clements (2007) | . | ICZN |
| Ocyceros | Coraciiformes | Clements (2007) | . | ICZN |
| Ocyropsis | Lobata | Harbison & Madin (1982) | . | ICZN |
| Oddoniodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Odessia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Odixia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Odobenus | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Odocoileus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Odonaticola | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Odonellia | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Odontadenia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Odontanthera | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Odontaspis | Lamniformes | Nelson (2006) | . | ICZN |
| Odontelytrum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Odonthalia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Odontitella | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Odontites | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Odontocarya | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Odontochilus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Odontochlamys | Chlamydodontida | Lynn (2008) | . | ICZN |
| Odontocline | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Odontoglossum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Odontolaingia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Odontolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Odontonema | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Odontophorella | Tintinnida | Lynn (2008) | . | ICZN |
| Odontophorus | Galliformes | Clements (2007) | . | ICZN |
| Odontophorus | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Odontophrynus | Anura | Vitt & Caldwell (2009) | Cycloramphidae. | ICZN |
| Odontorchilus | Passeriformes | Clements (2007) | . | ICZN |
| Odontorrhynchus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Odontoschisma | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Odontoseries | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Odontosoria | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Odontospiza | Passeriformes | Clements (2007) | . | ICZN |
| Odontostelma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Odontostomum | Asparagales | Mabberley (2008) | Tecophilaeaceae. | ICBN |
| Odoribacter | Bacteroidales | Hardham et al. (2008) | . | ICNB |
| Odorrana | Anura | Vitt & Caldwell (2009) | Ranidae. | ICZN |
| Odosicyos | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Odyssea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Odyssella | Rickettsiales | Garrity et al. (2005) | . | ICNB |
| Oeceoclades | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oecomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Oecopetalum | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Oedematopus | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Oedera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oedibasis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oedicladium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Oedina | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Oedipina | Caudata | Vitt & Caldwell (2009) | Plethodontidae. | ICZN |
| Oedipodiella | Gigaspermales | Goffinet et al. (2009) | . | ICBN |
| Oedipodium | Oedipodiales | Goffinet et al. (2009) | . | ICBN |
| Oedura | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Oemleria | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Oena | Columbiformes | Clements (2007) | . | ICZN |
| Oenanthe | Passeriformes | Clements (2007) | . | ICZN |
| Oenanthe | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oenocarpus | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Oenococcus | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Oenomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Oenophorachona | Exogemmida | Lynn (2008) | . | ICZN |
| Oenothera | Myrtales | Mabberley (2008) | Onagraceae. | ICBN |
| Oenotrichia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Oeonia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oeoniella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oerskovia | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Oerstedella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oerstedia | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Oerstedina | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Oestlundia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ofaiston | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Oftia | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Ogastemma | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Ogdeniella | Tectofilosida | Meisterfeld (2000); Cavalier-Smith & Chao (2003) | Psammonobiotidae. | ICZN |
| Ogimotoa | Vestibuliferida | Lynn (2008) | . | ICZN |
| Ogimotopsis | Vestibuliferida | Lynn (2008) | . | ICZN |
| Oglifa | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ogmodon | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Ognorhynchus | Psittaciformes | Clements (2007) | . | ICZN |
| Ohridospongilla | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Ohtaekwangia | Cytophagales | Yoon et al. (2011) | . | ICNB |
| Ohwia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oikomonas | Chromulinales | Kristiansen & Preisig (2001) | Chromulinaceae (uniflagellate). | ICBN |
| Oikopleura | Appendicularia | Fenaux (1998) | . | ICZN |
| Oiospermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Okamejei | Rajiformes | Nelson (2006) | . | ICZN |
| Okamia | Stolidobranchia | Monniot & Monniot (1972); Kott (1998) | Junior synonym of Metandrocarpa. | ICZN |
| Okamuraea | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Okapia | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Okenia | Caryophyllales | Mabberley (2008) | Nyctaginaceae. | ICBN |
| Okibacterium | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Okoubaka | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Olallamys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Olax | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Oldenburgia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oldenlandia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oldenlandiopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oldfeltia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oldfieldia | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Olea | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Oleandra | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Olearia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oleibacter | Oceanospirillales | Teramoto et al. (2011) | . | ICNB |
| Oleiphilus | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Oleispira | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Oleolophozia | Jungermanniales | Söderström et al. (2010) | . | ICBN |
| Olfersia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Olgaea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Olgantha | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Oligacanthorhynchus | Oligacanthorhynchida | Amin (1985) | . | ICZN |
| Oligactis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oliganthes | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oligella | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Oligocarpa | Stolidobranchia | Monniot & Monniot (1972) | Styelidae. | ICZN |
| Oligocarpus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oligoceras | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Oligochaeta | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oligochaetocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Oligochoerus | Acoela | Dörjes (1968); Hooge & Tyler (2005) | . | ICZN |
| Oligocladella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Oligocladus | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oligocodon | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oligodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Oligofilomorpha | Acoela | Faubel & Noreña (2001) | . | ICZN |
| Oligoisotricha | Vestibuliferida | Lynn (2008) | . | ICZN |
| Oligomeris | Brassicales | Mabberley (2008) | Resedaceae. | ICBN |
| Oligonema | Trichiales | Yamamoto (1998) | . | ICBN |
| Oligophyton | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oligoryzomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Oligosagitta | Aphragmophora | Kasatkina (1971); Kasatkina & Selivanova (2003) | Sagittidae. Now checking. | ICZN |
| Oligosoma | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Oligostachyum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oligoterorhynchus | Polymorphida | Amin (1985) | . | ICZN |
| Oligothrix | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oligotrema | Aspiraculata | Kott (1989); Monniot & Monniot (1990) | . | ICZN |
| Oligotrichum | Polytrichales | Goffinet et al. (2009) | . | ICBN |
| Oligotropha | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Olimarabidopsis | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Olindagorgia | Alcyonacea | Bayer (1981) | Gorgoniidae. | ICZN |
| Olindias | Limnomedusae | Bouillon et al. (2006) | . | ICZN |
| Olinia | Myrtales | Mabberley (2008) | Crypteroniaceae. | ICBN |
| Olisthodiscus | | Heywood & Leedale (2000); Yamaguchi et al. (2010) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. Informally excluded from Raphidomonadales (Yamaguchi et al., 2010). | ICBN |
| Olisthomys | Rodentia | McKenna & Bell (1997); Thorington, Jr. & Hoffmann (2005) | Later synonym of Petinomys. | ICZN |
| Olivaea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oliverella | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Oliveria | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oliveriana | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Olivibacter | Sphingobacteriales | Ntougias et al. (2007) | . | ICNB |
| Olleya | Flavobacteriales | Mancuso Nichols et al. (2005) | . | ICNB |
| Ollicola | Ochromonadales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Dinobryaceae (biflagellate). | ICBN |
| Ollotis | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Olmeca | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Olmediella | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Olneya | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Olpidiomorpha | Rozellopsidales | Dick (2001); Kirk et al. (2008) | Rozellopsidales. | ICBN |
| Olpidiopsis | Olpidiopsidales | Dick (2001); Kirk et al. (2008) | Olpidiopsidaceae. | ICBN |
| Olsenella | Coriobacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Olsynium | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Olyra | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Omanodinium | Peridiniales | Fensome et al. (1993) | Holocene. | ICBN |
| Omanosaura | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Ombellula | Pennatulacea | Williams (1995) | . | ICZN |
| Ombrana | Anura | Vitt & Caldwell (2009) | Dicroglossidae. | ICZN |
| Ombrocharis | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Ombronesus | Ptychomniales | Goffinet et al. (2009) | . | ICBN |
| Ombrophytum | Santalales | Mabberley (2008) | Balanophoraceae. | ICBN |
| Omegandra | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Omegastrombidium | Strombidiida | Lynn (2008) | . | ICZN |
| Omiltemia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Ommatodiscus | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Ommatophoca | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Ommatotriton | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Omoea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Omphacomeria | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Omphalanthus | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Omphalea | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Omphalocarpum | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Omphalodes | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Omphalogonus | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Omphalogramma | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Omphalolappula | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Omphalopappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Omphalopus | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Omphalotrix | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Oncella | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Oncicola | Oligacanthorhynchida | Amin (1985) | . | ICZN |
| Oncidium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oncinema | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Oncinocalyx | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Oncinotis | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Oncoba | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Oncocalamus | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Oncocalyx | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Oncophorus | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Oncosclera | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Oncosiphon | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oncosonderia | Plagiopylida | Lynn (2008) | . | ICZN |
| Oncosperma | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Oncostemum | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Oncostoma | Passeriformes | Clements (2007) | . | ICZN |
| Oncostylus | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Oncotheca | Oncothecales | Mabberley (2008) | Oncothecaceae. | ICBN |
| Ondatra | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Ondetia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ongokea | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Onikusa | Gelidiales | Schneider & Wynne (2007) | Later synonym of Gelidium. | ICBN |
| Onira | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Onkonema | Chroococcales | Yamagishi (2007) | . | ICBN |
| Onobrychis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Onoclea | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Ononis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Onopordum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Onoseris | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Onosma | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Onosmodium | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Onotia | Hadromerida | Rützler (2002) | . | ICZN |
| Onubactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Onuris | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Onychium | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Onychocolax | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Onychodactylus | Caudata | Vitt & Caldwell (2009) | Hynobiidae. | ICZN |
| Onychodromopsis | Sporadotrichida | Lynn (2008) | . | ICZN |
| Onychodromus | Sporadotrichida | Lynn (2008) | . | ICZN |
| Onychogalea | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Onychognathia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Onychognathus | Passeriformes | Clements (2007) | . | ICZN |
| Onychomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Onychopetalum | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Onychoprion | Charadriiformes | Clements (2007) | . | ICZN |
| Onychorhynchus | Passeriformes | Clements (2007) | . | ICZN |
| Onychosepalum | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Oocardium | Desmidiales | Gontcharov (2008) | . | ICBN |
| Oocephalus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Oocystidium | Chlorellales | Krienitz & Bock (2011) | As Oocystis-clade or Oocystaceae. | ICBN |
| Oocystis | Chlorellales | Darienko et al. (2010); Paž;outová et al. (2010) | As Oocystis-clade or Oocystaceae. | ICBN |
| Oodinioides | | Fensome et al. (1993); Skovgaard et al. (2007) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Dinozoa - Class Dinophyceae. Former Blastodiniales. | ICBN |
| Oodinium | | Fensome et al. (1993); Skovgaard et al. (2007) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Dinozoa - Class Dinophyceae. Former Blastodiniales. | ICBN |
| Oolina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ellipsolagenidae. | ICZN |
| Oolithotus | Coccolithales | Jordan et al. (2004) | "Oolithus" is an incorrect spelling. Calcidiscaceae. | ICBN |
| Oonautes | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Oonopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ooperipatellus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Ooperipatus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Oophaga | Anura | Vitt & Caldwell (2009) | Dendrobatidae. | ICZN |
| Oophytum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Ooplanctella | Chlorellales | Pažoutová et al. (2010) | As Oocystis-clade or Oocystaceae. | ICBN |
| Oopsacas | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Oopyxis | Arcellinida | Meisterfeld (2000) | incertae sedis. | ICZN |
| Opalina | Opalinales | Delvinquier & Patterson (2000) | . | ICZN |
| Opalinopsis | Astomatophorida | Lynn (2008) | . | ICZN |
| Oparanthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Opephyllum | Ceramiales | Schneider & Wynne (2007) | Later synonym of Martensia. | ICBN |
| Opercularella | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Opercularia | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Opercularia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Operculariella | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Operculicarya | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Operculigera | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Operculina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nummulitidae. | ICZN |
| Operculina | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Opheodrys | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Ophiaster | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Syracosphaeraceae. | ICBN |
| Ophidiocephalus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Ophidiogorgia | Alcyonacea | Bayer (1981) | Primnoidae. | ICZN |
| Ophidion | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ophidocladus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Ophinella | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Ophiobotrys | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Ophiocaryon | Sabiales | Mabberley (2008) | Sabiaceae. | ICBN |
| Ophiochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ophiocolea | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Ophiocytium | Mischococcales | Ettl (1978) | . | ICBN |
| Ophiodes | Squamata | Vitt & Caldwell (2009) | Anguidae. | ICZN |
| Ophiodiscus | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Ophioglossella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ophioglossum | Ophioglossales | Christenhusz et al. (2011) | . | ICBN |
| Ophioidina | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Ophiomorus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Ophionella | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Ophiophagus | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Ophiopogon | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Ophiorrhiza | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Ophiorrhiziphyllon | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Ophioscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Ophiothrix | Nostocales | Sant'Anna et al. (2010) | . | ICBN |
| Ophiotuba | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Lagynidae. | ICZN |
| Ophisaurus | Squamata | Vitt & Caldwell (2009) | Anguidae. | ICZN |
| Ophisops | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Ophiuraespira | Apostomatida | Lynn (2008) | . | ICZN |
| Ophiurephelota | Exogenida | Lynn (2008) | . | ICZN |
| Ophiuros | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ophlitaspongia | Poecilosclerida | Hooper (2002) | . | ICZN |
| Ophrestia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ophryacus | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Ophrydium | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Ophryocephalus | Exogenida | Lynn (2008) | . | ICZN |
| Ophryocystis | Neogregarinorida | Perkins et al. (2000) | . | ICZN |
| Ophryodendron | Exogenida | Lynn (2008) | . | ICZN |
| Ophryoglena | Ophryoglenida | Lynn (2008) | . | ICZN |
| Ophryophryne | Anura | Vitt & Caldwell (2009) | Megophryidae. | ICZN |
| Ophryoscolex | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Ophryosporus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ophrypetalum | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Ophrys | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ophthalmina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ophthalmidiidae. | ICZN |
| Ophthalmoblapton | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Opilia | Santalales | Mabberley (2008) | Opiliaceae. | ICBN |
| Opipeuter | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Opisthiolepis | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Opisthocentra | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Opisthocomus | Gruiformes | Clements (2007) | . | ICZN |
| Opisthodon | Pleurostomatida | Lynn (2008) | . | ICZN |
| Opisthodon | Anura | Vitt & Caldwell (2009) | Limnodynastidae. | ICZN |
| Opisthonecta | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Opisthopappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Opisthopatus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Opisthoplus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Opisthoprora | Apodiformes | Clements (2007) | . | ICZN |
| Opisthostomatella | Colpodida | Lynn (2008) | . | ICZN |
| Opisthostyla | Peritrichida | Lynn (2008); Zhan et al. (2009) | Later synonym of Rhabdostyla. | ICZN |
| Opisthothylax | Anura | Vitt & Caldwell (2009) | Hyperoliidae. | ICZN |
| Opisthotrichum | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Opisthotropis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Opithandra | Lamiales | Mabberley (2008); Möller et al. (2011) | Gesneriaceae. Later synonym of Oreocharis. | ICBN |
| Opitutus | Opitutales | Garrity et al. (2005); Choo et al. (2007) | . | ICNB |
| Opizia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oplismenopsis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oplismenus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oplonia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Oplopanax | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Oplorhiza | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Oplurus | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Opocunonia | Oxalidales | Mabberley (2008) | Cunoniaceae. | ICBN |
| Opoideia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Opopanax | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oporornis | Passeriformes | Clements (2007) | . | ICZN |
| Opsicarpium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Opuntia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Opuntiella | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Opydorscus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Oractis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Oramoeba | Schizopyrenida | De Jonckheere et al. (2011) | . | ICZN |
| Orangaslia | Alcyonacea | Alderslade (2001) | Xeniidae. | ICZN |
| Orania | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Oraniopsis | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Orbea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Orbexilum | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Orbitina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Discorbidae. | ICZN |
| Orbocephalus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Orbopercularia | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Orbopyxidiella | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Orborhabdostyla | Peritrichida | Foissner et al. (2009) | . | ICZN |
| Orbulina | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Globigerinidae. | ICZN |
| Orbulinelloides | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Saccamminidae. | ICZN |
| Orbus | | Volkmann et al. (2010) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria. | ICNB |
| Orcadia | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hastigerinidae. | ICZN |
| Orcaella | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Orcavia | | Lynn (2008) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Ciliophora. | ICZN |
| Orchadocarpa | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Orcheobius | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Orchesticus | Passeriformes | Clements (2007) | . | ICZN |
| Orchidantha | Zingiberales | Mabberley (2008) | Lowiaceae. | ICBN |
| Orchipedum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Orchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Orchistoma | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Orchistomella | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Orchitophrya | Philasterida | Lynn (2008) | . | ICZN |
| Orcinus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Orculifilum | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Orcuttia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ordospora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Oreacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Oreamnos | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Oreanthes | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Oreas | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Orectanthe | Poales | Mabberley (2008) | Xyridaceae. | ICBN |
| Orectolobus | Orectolobiformes | Nelson (2006) | . | ICZN |
| Orectostomina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spiroplectamminidae. | ICZN |
| Oreella | Echiniscoidea | Kinchin (1994) | . | ICZN |
| Oregodasys | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Oreithales | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Orenia | Halanaerobiales | Garrity et al. (2005) | . | ICNB |
| Oreobambos | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oreobates | Anura | Vitt & Caldwell (2009) | Brachycephalidae. | ICZN |
| Oreobliton | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Oreobolopsis | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Oreobolus | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Oreocalamus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Oreocallis | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Oreocereus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Oreochaenactis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oreocharis | Passeriformes | Clements (2007) | . | ICZN |
| Oreocharis | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Oreochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oreochrysum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oreocnide | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Oreocome | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oreocomopsis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oreodeira | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Oreogrammitis | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Oreoica | Passeriformes | Clements (2007) | . | ICZN |
| Oreolalax | Anura | Vitt & Caldwell (2009) | Megophryidae. | ICZN |
| Oreoleysera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oreoloma | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Oreomanes | Passeriformes | Clements (2007) | . | ICZN |
| Oreomitra | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Oreomunnea | Fagales | Mabberley (2008) | Juglandaceae. | ICBN |
| Oreomyrrhis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oreomystis | Passeriformes | Clements (2007) | . | ICZN |
| Oreonana | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oreonax | Primates | Groves (2005) | . | ICZN |
| Oreonesion | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Oreonympha | Apodiformes | Clements (2007) | . | ICZN |
| Oreopanax | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Oreophasis | Galliformes | Clements (2007) | . | ICZN |
| Oreopholus | Charadriiformes | Clements (2007) | . | ICZN |
| Oreophryne | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Oreophrynella | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Oreophylax | Passeriformes | Clements (2007) | . | ICZN |
| Oreophysa | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oreophyton | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Oreopolus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oreopsittacus | Psittaciformes | Clements (2007) | . | ICZN |
| Oreorchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Oreornis | Passeriformes | Clements (2007) | . | ICZN |
| Oreortyx | Galliformes | Clements (2007) | . | ICZN |
| Oreoschimperella | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oreoscoptes | Passeriformes | Clements (2007) | . | ICZN |
| Oreoscopus | Passeriformes | Clements (2007) | . | ICZN |
| Oreosolen | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Oreosparte | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Oreostemma | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oreostruthus | Passeriformes | Clements (2007) | . | ICZN |
| Oreothraupis | Passeriformes | Clements (2007) | . | ICZN |
| Oreotragus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Oreotrochilus | Apodiformes | Clements (2007) | . | ICZN |
| Oreoweisia | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Oreoxis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oresitrophe | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Orestias | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Orfilea | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Oribacterium | Clostridiales | Carlier et al. (2004) | . | ICNB |
| Oridorsalis | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Oridorsalidae. | ICZN |
| Orientia | Rickettsiales | Garrity et al. (2005) | . | ICNB |
| Origanum | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Origma | Passeriformes | Clements (2007) | . | ICZN |
| Orinus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oriocalotes | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Oriolia | Passeriformes | Clements (2007) | . | ICZN |
| Oriolus | Passeriformes | Clements (2007) | . | ICZN |
| Oriotarus | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Orites | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Oritrophium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oriturus | Passeriformes | Clements (2007) | . | ICZN |
| Orixa | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Orlaya | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Orleanesia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Orlikia | Alcyonacea | Williams (2000) | Nidaliidae. | ICZN |
| Orlitia | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Ormieresia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Ormocarpopsis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ormocarpum | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ormopterum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Ormosciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Ormosella | Tintinnida | Lynn (2008) | . | ICZN |
| Ormosia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ormosolenia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Ornamentula | Chaetonotida | Balsamo et al. (2009) | . | ICZN |
| Ornichia | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Ornithinibacillus | Bacillales | Mayr et al. (2006) | . | ICNB |
| Ornithinibacter | Micrococcales | Xiao et al. (2011); Ludwig et al. (2012) | Intrasporangiaceae. | ICNB |
| Ornithinicoccus | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Ornithinimicrobium | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Ornithion | Passeriformes | Clements (2007) | . | ICZN |
| Ornithobacterium | Flavobacteriales | Garrity et al. (2005) | . | ICNB |
| Ornithoboea | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Ornithocarpa | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Ornithocephalus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ornithocercus | Dinophysiales | Fensome et al. (1993) | . | ICBN |
| Ornithochilus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ornithogalum | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Ornithoglossum | Liliales | Mabberley (2008) | Colchicaceae. | ICBN |
| Ornithopus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ornithorhynchus | Monotremata | McKenna & Bell (1997) | . | ICZN |
| Ornithostaphylos | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Oroaetus | Falconiformes | Clements (2007) | . | ICZN |
| Orobanche | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Orochaenactis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Orogenia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Orontium | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Orontobryum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Oroperipatus | Euonychophora | Peck (1975) | Peripatidae. | ICZN |
| Oropetium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Orophea | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Orophochilus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Orostachys | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Oroxylum | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Oroya | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Orphanodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Orphium | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Orsomia | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Ortachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ortalis | Galliformes | Clements (2007) | . | ICZN |
| Ortegia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Ortegocactus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Orthaea | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Orthanthera | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Orthilia | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Orthion | Malpighiales | Mabberley (2008) | Violaceae. | ICBN |
| Orthiopteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Orthoamblystegium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthoamphisiella | Stichotrichida | Lynn (2008) | . | ICZN |
| Orthocarpus | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Orthocaulis | Jungermanniales | Söderström et al. (2010) | . | ICBN |
| Orthoceras | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Orthoclada | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Orthodicranum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Orthodonella | Synhymeniida | Lynn (2008) | . | ICZN |
| Orthodontium | Orthodontiales | Stech & Frey (2008); Goffinet et al. (2009) | . | ICBN |
| Orthodontopsis | Orthodontiales | Stech & Frey (2008); Goffinet et al. (2009) | . | ICBN |
| Orthogeomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Orthogoneuron | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Orthogonys | Passeriformes | Clements (2007) | . | ICZN |
| Orthogynium | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Orthokreyella | Cyrtolophosidida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Ortholinea | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Orthomene | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Orthomnion | Bryales | Goffinet et al. (2009) | . | ICBN |
| Orthomorphina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Stilostomellidae. | ICZN |
| Orthonyx | Passeriformes | Clements (2007) | . | ICZN |
| Orthophytum | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Orthopichonia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Orthoplecta | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Cassidulinidae. | ICZN |
| Orthopsittaca | Psittaciformes | Clements (2007) | . | ICZN |
| Orthopterum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Orthopterygium | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Orthopyxis | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Orthoraphium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Orthorhyncus | Apodiformes | Clements (2007) | . | ICZN |
| Orthorrhynchidium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthorrhynchium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthosia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Orthosiphon | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Orthosomella | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Orthosphenia | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Orthostichella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthostichidium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthostichopsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthothecium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Orthothylax | Commelinales | Mabberley (2008) | Philydraceae. | ICBN |
| Orthotomus | Passeriformes | Clements (2007) | . | ICZN |
| Orthotrichum | Orthotrichales | Goffinet et al. (2009) | . | ICBN |
| Orthotrochilia | Dysteriida | Lynn (2008) | . | ICZN |
| Orthrosanthus | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Orthurceolaria | Mobilida | Lynn (2008) | . | ICZN |
| Orthurus | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Ortygospiza | Passeriformes | Clements (2007) | . | ICZN |
| Ortyxelos | Gruiformes | Clements (2007) | . | ICZN |
| Orychophragmus | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Oryctanthus | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Orycteropus | Tubulidentata | McKenna & Bell (1997) | . | ICZN |
| Oryctes | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Oryctina | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Oryctoderma | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hemisphaeramminidae. | ICZN |
| Oryctolagus | Lagomorpha | McKenna & Bell (1997) | . | ICZN |
| Oryx | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Oryxis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oryza | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oryzidium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oryzihumus | Micrococcales | Kageyama et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Oryzoborus | Passeriformes | Clements (2007) | . | ICZN |
| Oryzolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Oryzomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Oryzopsis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oryzorictes | Afrosoricida | McKenna & Bell (1997); Stanhope et al. (1998) | Tenrecidae. | ICZN |
| Orzeliscus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Osa | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Osangularia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Osangulariidae. | ICZN |
| Osbeckia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Osbertia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Osbornia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Osbornictis | Carnivora | McKenna & Bell (1997); Wozencraft (2005) | Later synonym of Genetta. | ICZN |
| Oscaecilia | Gymnophiona | Vitt & Caldwell (2009) | "Caeciliidae". | ICZN |
| Oscarella | Homosclerophorida | Muricy & Díaz (2002) | . | ICZN |
| Oschatzia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oscillatoria | Oscillatoriales | Hoffmann et al. (2005) | . | ICBN |
| Oscillibacter | Clostridiales | Iino et al. (2007) | . | ICNB |
| Oscillochloris | Chloroflexales | Garrity et al. (2005) | . | ICNB |
| Oscillosignum | Dactylopodida | Rogerson & Patterson (2000); Smirnov et al. (2005) | Vexilliferidae. | ICZN |
| Oscillospira | Clostridiales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Oscularia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Osculatia | Bryales | Goffinet et al. (2009) | . | ICBN |
| Oserya | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Osgoodomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Osmadenia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Osmanthus | Lamiales | Mabberley (2008) | Oleaceae. | ICBN |
| Osmelia | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Osmiopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Osmitopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Osmolindsaea | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Osmorhiza | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Osmoxylon | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Osmunda | Osmundales | Christenhusz et al. (2011) | . | ICBN |
| Osmundaria | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Osmundastrum | Osmundales | Christenhusz et al. (2011) | . | ICBN |
| Osmundea | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Osornophryne | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Ossaea | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Ossiculum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ossiella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Osteocarpum | Caryophyllales | Mabberley (2008) | Chenopodiaceae. | ICBN |
| Osteocephalus | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Osteolaemus | Crocodylia | Vitt & Caldwell (2009) | Crocodylidae. | ICZN |
| Osteomeles | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Osteophloeum | Magnoliales | Mabberley (2008) | Myristicaceae. | ICBN |
| Osteopilus | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Osteospermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Osterwaldiella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Ostiobaculites | Lituolida | Kaminski (2000) | Ammomarginulininae. | ICZN |
| Ostiophyllum | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Ostodes | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Ostracodinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Ostrearia | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Ostreococcus | Mamiellales | Marin & Melkonian (2010) | . | ICBN |
| Ostreopsis | Gonyaulacales | Fensome et al. (1993) | . | ICBN |
| Ostrowskia | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Ostrya | Fagales | Mabberley (2008) | Betulaceae. | ICBN |
| Ostryocarpus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ostryopsis | Fagales | Mabberley (2008) | Betulaceae. | ICBN |
| Oswaldella | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Osyridicarpos | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Osyris | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Otacanthus | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Otachyrium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Otaria | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Otariodibacter | Pasteurellales | Hansen et al. (2012) | . | ICNB |
| Otatea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oteiza | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Otholobium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Othonna | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Otidiphaps | Columbiformes | Clements (2007) | . | ICZN |
| Otion | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Otiophora | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Otis | Gruiformes | Clements (2007) | . | ICZN |
| Otoba | Magnoliales | Mabberley (2008) | Myristicaceae. | ICBN |
| Otocarpus | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Otocelis | Acoela | Dörjes (1968); Faubel & Noreña (2001) | . | ICZN |
| Otochilus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Otocryptis | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Otocyon | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Otoglossum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Otohydra | Actinulida | Bouillon et al. (2006) | . | ICZN |
| Otolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Otolemur | Primates | Groves (2005) | . | ICZN |
| Otomeria | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Otomops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Otomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Otonemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Otonephelium | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Otonycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Otonyctomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Otopappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Otophryne | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Otoporpa | Narcomedusae | Bouillon et al. (2006) | . | ICZN |
| Otoptera | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Otopteropus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Otospermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Otosphaera | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Otostegia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Otostephanos | Bdelloida | Segers (2002); Segers (2007) | . | ICZN |
| Otostylis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ototylomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Ototyphlonemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Ottelia | Alismatales | Mabberley (2008) | Hydrocharitaceae. | ICBN |
| Ottleya | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ottoa | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Ottochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ottoschmidtia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Ottoschulzia | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Ottosonderia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Ottowia | Burkholderiales | Spring et al. (2004) | . | ICNB |
| Ottowphrya | Platyophryida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Otus | Strigiformes | Clements (2007) | . | ICZN |
| Oubanguia | Ericales | Mabberley (2008) | Lecythidaceae. | ICBN |
| Ougeinia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oulactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Oulangia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Oulastrea | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Oulophyllia | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Ouratea | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Ourebia | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Ourisia | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Outreya | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ovabunda | Alcyonacea | Alderslade (2001) | Xeniidae. | ICZN |
| Ovactis | Ceriantharia | Tiffon (1987) | . | ICZN |
| Ovalopodium | Himatismenida | Rogerson & Patterson (2000); Cavalier-Smith et al. (2004); Smirnov et al. (2011) | . | ICZN |
| Ovalorhabdos | Haptorida | Lynn (2008) | . | ICZN |
| Ovammina | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Saccamminidae. | ICZN |
| Ovanthula | Ceriantharia | Tiffon (1987) | . | ICZN |
| Ovatisporangium | Pythiales | Bala et al. (2010); Uzuhashi et al. (2010) | Later synonym of Phytopythium. | ICBN |
| Ovavesicola | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Ovibos | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Ovicides | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Carcinonemertidae. | ICZN |
| Ovidia | Malvales | Mabberley (2008) | Thymelaeaceae. | ICBN |
| Ovipleistophora | Microsporida | Pekkarinen & Nilsen (2002) | . | ICZN |
| Ovis | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Ovivora | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Ovolembus | Philasterida | Lynn (2008) | . | ICZN |
| Ovophis | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Ovulinata | Euglyphida | Meisterfeld (2000); Cavalier-Smith & Chao (2003); Howe et al. (2011) | . | ICZN |
| Owenia | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Owenweeksia | Flavobacteriales | Lau et al. (2005) | . | ICNB |
| Owilfordia | Polymorphida | Amin (1985) | . | ICZN |
| Oxalicibacterium | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Oxalis | Oxalidales | Mabberley (2008) | Oxalidaceae. | ICBN |
| Oxalobacter | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Oxalophagus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Oxandra | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Oxera | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Oxnerella | | Mikrjukov et al. (2000); Cavalier-Smith & von der Heyden (2007); Yabuki et al. (2012) | Domain Eucarya - Phylum Heliozoa - Class Centrohelea. | ICZN |
| Oxobacter | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Oxyanthus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oxybelis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Oxycarpha | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oxycaryum | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Oxyceros | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Oxychloe | Poales | Mabberley (2008) | Juncaceae. | ICBN |
| Oxychloris | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oxychonina | Cryptogemmida | Lynn (2008) | . | ICZN |
| Oxycorynia | Aplousobranchia | Monniot & Monniot (1972); Kott (1998) | Junior synonym of Nephtheis. | ICZN |
| Oxydactyla | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Oxydendrum | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Oxygonum | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Oxygraphis | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Oxygyne | Dioscoreales | Mabberley (2008) | Thismiaceae. | ICBN |
| Oxylabes | Passeriformes | Clements (2007) | . | ICZN |
| Oxylobium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oxylobus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oxymitra | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Oxymonas | Oxymonadida | Brugerolle & Lee (2000) | . | ICZN |
| Oxymycterus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Oxynotus | Squaliformes | Nelson (2006) | . | ICZN |
| Oxyosmyles | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Oxypappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oxypetalum | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Oxyphyllum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oxyphysis | Dinophysiales | Fensome et al. (1993) | . | ICBN |
| Oxypogon | Apodiformes | Clements (2007) | . | ICZN |
| Oxypolella | Heteronemertea | Gibson (1995) | . | ICZN |
| Oxypolia | Heteronemertea | Gibson (1995) | . | ICZN |
| Oxypolis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Oxypora | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Oxyposthia | Acoela | Dörjes (1968); Hooge & Tyler (2005) | . | ICZN |
| Oxyrhabdium | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Oxyrhachis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oxyrhopus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Oxyrhynchus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oxyria | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Oxyrrhis | Oxyrrhida | Dodge & Lee (2000) | . | ICZN |
| Oxyrrhynchium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Oxyruncus | Passeriformes | Clements (2007) | . | ICZN |
| Oxysmilia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Oxyspora | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Oxystelma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Oxystigma | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oxystylis | Brassicales | Mabberley (2008) | Cleomaceae. | ICBN |
| Oxytenanthera | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Oxytenia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Oxytethya | Hadromerida | Sarà (2002) | . | ICZN |
| Oxytheca | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Oxytoxum | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae - Subclass Peridiniphycidae. | ICBN |
| Oxytricha | Sporadotrichida | Lynn (2008) | . | ICZN |
| Oxytropis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Oxyura | Anseriformes | Clements (2007) | . | ICZN |
| Oxyuranus | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Oyedaea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ozawaia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Elphidiidae. | ICZN |
| Ozdikmenella | | Bass et al. (2009); Özdikmen (2009) | Domain Eucarya - Phylum Cercozoa - Class Granofilosea. Substitute name for Clathrella. | ICZN |
| Ozophora | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Ozoroa | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Ozothamnus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ozotoceros | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |