| Genus |
Order |
Reference |
Note |
Nomenclature |
| T | |
| Tabachnickia | Amphidiscosida | Tabachnick & Menshenina (2002); Özdikmen (2010) | Replacement name for Platella. | ICZN |
| Tabanispora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Tabebuia | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Tabernaemontana | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tabernanthe | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tabulocalyx | Haplosclerida | Desqueyroux-Faúndez & Valentine (2002) | . | ICZN |
| Tacarcuna | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Tacazzea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tacca | Dioscoreales | Mabberley (2008) | Taccaceae. | ICBN |
| Taccarum | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Tachia | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Tachiadenus | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Tachigali | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tachornis | Apodiformes | Clements (2007) | . | ICZN |
| Tachuris | Passeriformes | Clements (2007) | . | ICZN |
| Tachybaptus | Podicipediformes | Clements (2007) | . | ICZN |
| Tachyblaston | Exogenida | Lynn (2008) | . | ICZN |
| Tachycineta | Passeriformes | Clements (2007) | . | ICZN |
| Tachycnemis | Anura | Vitt & Caldwell (2009) | Hyperoliidae. | ICZN |
| Tachyeres | Anseriformes | Clements (2007) | . | ICZN |
| Tachyglossus | Monotremata | McKenna & Bell (1997) | . | ICZN |
| Tachygyia | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Tachymarptis | Apodiformes | Clements (2007) | . | ICZN |
| Tachymenis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tachyoryctes | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tachyphonus | Passeriformes | Clements (2007) | . | ICZN |
| Tachysoma | Sporadotrichida | Lynn (2008) | . | ICZN |
| Tacinga | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Tadarida | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Tadehagi | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tadorna | Anseriformes | Clements (2007) | . | ICZN |
| Taeniatherum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Taenidia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Taeniella | Ichthyophonida | Cafaro (2005); Kirk et al. (2008) | Eccrinales in mycology. | ICZN |
| Taeniellopsis | Ichthyophonida | Cafaro (2005); Kirk et al. (2008) | Eccrinales in mycology. | ICZN |
| Taeniocineta | Thigmotrichida | Lynn (2008) | . | ICZN |
| Taeniocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Taenioma | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Taeniophallus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Taeniophyllum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Taeniopygia | Passeriformes | Clements (2007) | . | ICZN |
| Taeniorhachis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Taeniorrhiza | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Taeniotriccus | Passeriformes | Clements (2007) | . | ICZN |
| Taenitis | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Taeniura | Myliobatiformes | Nelson (2006) | . | ICZN |
| Taeromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tagetes | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tagonemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003); Kajihara et al. (2008) | Junior synonym of Amphiporus. | ICZN |
| Taiaroa | Alcyonacea | Bayer (1981) | Taiaroidae. | ICZN |
| Tainia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Taiwania | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Taiwanobryum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Takakia | Takakiales | Goffinet et al. (2009) | . | ICBN |
| Takayama | Gymnodiniales | de Salas et al. (2003) | . | ICBN |
| Takayanagia | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Cassidulinidae. | ICZN |
| Takhtajania | Canellales | Mabberley (2008) | Winteraceae. | ICBN |
| Takydromus | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Talbotiella | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Talegalla | Galliformes | Clements (2007) | . | ICZN |
| Taliaferria | Vestibuliferida | Lynn (2008) | . | ICZN |
| Talinaria | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Talinella | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Talinopsis | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Talinum | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Talisia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Talitrochilodon | Chlamydodontida | Lynn (2008) | . | ICZN |
| Talizona | Endogenida | Lynn (2008) | . | ICZN |
| Talpa | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Tamamschjanella | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tamamschjania | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tamananthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tamandua | Xenarthra | McKenna & Bell (1997) | . | ICZN |
| Tamarindus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tamarisca | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tamarix | Caryophyllales | Mabberley (2008) | Tamaricaceae. | ICBN |
| Tamaulipa | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tambourissa | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Tamias | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tamiasciurus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tamijea | Zingiberales | Mabberley (2008) | Zingiberaceae. | ICBN |
| Tamilnadia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tamiops | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tamlana | Flavobacteriales | Lee (2007) | . | ICNB |
| Tammsia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tamonea | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Tamoya | Cubomedusae | Kramp (1961) | . | ICZN |
| Tamridaea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tana | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tanacetipathes | Antipatharia | Opresko (2001) | . | ICZN |
| Tanacetopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tanacetum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tanakaea | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Tanakaella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tanaorhamphus | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Tanarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Tangara | Passeriformes | Clements (2007) | . | ICZN |
| Tannerella | Bacteroidales | Garrity et al. (2005) | . | ICNB |
| Tannodia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Tanquana | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Tantalophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tanticharoenia | Rhodospirillales | Yukphan et al. (2008) | . | ICNB |
| Tantilla | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tantillita | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tanygnathus | Psittaciformes | Clements (2007) | . | ICZN |
| Tanysiptera | Coraciiformes | Clements (2007) | . | ICZN |
| Tanystomium | Philasterida | Lynn (2008) | Nomen nudum. | ICZN |
| Taoniscus | Tinamiformes | Clements (2007) | . | ICZN |
| Taonura | Dictyoceratida | Cook & Bergquist (2002) | . | ICZN |
| Tapecomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Tapeinia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Tapeinidium | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Tapeinochilos | Zingiberales | Mabberley (2008) | Costaceae. | ICBN |
| Tapeinodasya | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tapeinosperma | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Tapeinostemon | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Tapera | Cuculiformes | Clements (2007) | . | ICZN |
| Tapheocarpa | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Taphozous | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Taphrocampa | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Taphrolesbia | Apodiformes | Clements (2007) | . | ICZN |
| Tapinanthus | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Tapinothrix | Pseudanabaenales | Hoffmann et al. (2005) | . | ICBN |
| Tapirira | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Tapirus | Perissodactyla | McKenna & Bell (1997) | . | ICZN |
| Tapiscia | Huerteales | Mabberley (2008) | Tapisciaceae. | ICBN |
| Taplinia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tapoides | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Tappanella | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glandulinidae. | ICZN |
| Taprobanea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tapura | Malpighiales | Mabberley (2008) | Dichapetalaceae. | ICBN |
| Tara | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Taraba | Passeriformes | Clements (2007) | . | ICZN |
| Taralea | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tarasa | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Taraxacum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Taraxia | Myrtales | Mabberley (2008) | Onagraceae. | ICBN |
| Taraxis | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Tarchonanthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tardiphaga | Rhizobiales | De Meyer et al. (2012) | . | ICNB |
| Tardivesicula | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Tarenna | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tarennoidea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tarentola | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Targionia | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Taricha | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Tarigidia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tarrhomyos | Heteronemertea | Gibson (1995) | . | ICZN |
| Tarsiger | Passeriformes | Clements (2007) | . | ICZN |
| Tarsipes | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Tarsius | Primates | McKenna & Bell (1997) | . | ICZN |
| Tarsomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tasmacetus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Tasmanaria | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tasmanipatus | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Tassadia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tateanthus | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tateomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tatera | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Taterillus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tateyamaria | Rhodobacterales | Kurahashi & Yokota (2007) | . | ICNB |
| Tatianyx | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tatumella | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Taudactylus | Anura | Vitt & Caldwell (2009) | Myobatrachidae. | ICZN |
| Tauraco | Cuculiformes | Clements (2007) | . | ICZN |
| Taurida | Acoela | Faubel & Noreña (2001) | . | ICZN |
| Tauriella | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Taurotragus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Tauscheria | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Tauschia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tavaresia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Taverniera | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tawitawia | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Textulariidae. | ICZN |
| Taxidea | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Taxilejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Taxillus | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Taxipathes | Antipatharia | Opresko (2002) | . | ICZN |
| Taxiphyllopsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Taxiphyllum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Taxitheliella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Taxithelium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Taxodiomeria | Cupressales | Mabberley (2008) | xTaxodiomeria. Taxodium x Cryptomeria hybrids. | ICBN |
| Taxodium | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Taxus | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Tayassu | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Taylorella | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Tayloria | Splachnales | Goffinet et al. (2009) | . | ICBN |
| Tayloriella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tayloriophyton | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Taylorophycus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Tchadorhynchus | Oligacanthorhynchida | Amin (1985) | . | ICZN |
| Tchagra | Passeriformes | Clements (2007) | . | ICZN |
| Tchihatchewia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Teagueia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tealianthus | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Tealidium | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Technitella | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Saccamminidae. | ICZN |
| Teclaia | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tecoma | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Tecomanthe | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Tecomella | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Tecophilaea | Asparagales | Mabberley (2008) | Tecophilaeaceae. | ICBN |
| Tectaria | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Tectatodinium | Gonyaulacales | Fensome et al. (1993) | Holocene. | ICBN |
| Tectibacter | Rickettsiales | Garrity et al. (2005) | . | ICNB |
| Tecticornia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Tectillaria | Appendicularia | Fenaux (1998) | . | ICZN |
| Tectiphiala | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Tectitethya | Hadromerida | Sarà (2002) | . | ICZN |
| Tectohymena | Bursariomorphida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Tectona | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Tecunumania | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Tedania | Poecilosclerida | Van Soest & Hajdu (2002) | . | ICZN |
| Tedaniophorbas | Poecilosclerida | Hooper (2002) | . | ICZN |
| Teedia | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Teesdalia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Tegicornia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Tegorhynchus | Echinorhynchida | Amin (1985) | . | ICZN |
| Tehuana | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Teichococcus | Rhodospirillales | Garrity et al. (2005); Sánchez-Porro et al. (2009) | Later synonym of Roseomonas. | ICNB |
| Teichonopsis | Leucosolenida | Borojevic et al. (2002) | . | ICZN |
| Teijsmanniodendron | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Teilingia | Desmidiales | Gontcharov (2008) | . | ICBN |
| Teira | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Teissiera | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Teius | Squamata | Vitt & Caldwell (2009) | Teiidae. | ICZN |
| Teixeiranthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Telacanthura | Apodiformes | Clements (2007) | . | ICZN |
| Telactinia | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Telammina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Telamminidae. | ICZN |
| Telamodinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Telanthophora | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Telaranea | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Teleaulax | Pyrenomonadales | Clay et al. (1999); Novarino (2003) | . | ICBN |
| Telectadium | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Teledromas | Passeriformes | Clements (2007) | . | ICZN |
| Telekia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Telephium | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Telescopus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Telespiza | Passeriformes | Clements (2007) | . | ICZN |
| Telesto | Alcyonacea | Bayer (1981) | Clavulariidae. | ICZN |
| Telestula | Alcyonacea | Bayer (1981) | Clavulariidae. | ICZN |
| Telfairia | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Telipogon | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Telitoxicum | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Tellima | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Telluria | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Telmatactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Telmatobacter | Acidobacteriales | Pankratov et al. (2012) | . | ICNB |
| Telmatobius | Anura | Vitt & Caldwell (2009) | Ceratophryidae. | ICZN |
| Telmatobufo | Anura | Vitt & Caldwell (2009) | Calyptocephalellidae. | ICZN |
| Telmatocola | Planctomycetales | Kulichevskaya et al. (2012) | . | ICNB |
| Telmatophila | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Telmatospirillum | Rhodospirillales | Sizova et al. (2007) | . | ICNB |
| Telomyxa | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Telonema | Telonemida | Cavalier-Smith (1996/7) | . | ICZN |
| Telopea | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Telophorus | Passeriformes | Clements (2007) | . | ICZN |
| Telosentis | Echinorhynchida | Amin (1985) | . | ICZN |
| Telosma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Telostomatella | Colpodida | Lynn (2008); Bourland et al. (2011) | . | ICZN |
| Telotrochidium | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Temburongia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Temenuchus | Passeriformes | Clements (2007) | . | ICZN |
| Temera | Torpediniformes | Nelson (2006) | . | ICZN |
| Temnadenia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Temnocalyx | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Temnogametum | Zygnematales | Gontcharov (2008) | . | ICBN |
| Temnoma | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Temnopteryx | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Temnotrochus | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Temnurus | Passeriformes | Clements (2007) | . | ICZN |
| Temochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Templetonia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tenacibaculum | Flavobacteriales | Garrity et al. (2005) | . | ICNB |
| Tenaciphyllum | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Tenarea | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Tengia | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Teniolophora | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Tennantia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tenrec | Afrosoricida | McKenna & Bell (1997); Stanhope et al. (1998) | Tenrecidae. | ICZN |
| Tenrhynea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tentorina | Spirophorida | Hooper & Van Soest (2002) | . | ICZN |
| Tentorium | Hadromerida | Boury-Esnault (2002) | . | ICZN |
| Tenuibacillus | Bacillales | Ren & Zhou (2005) | . | ICNB |
| Tenuignathia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Tenuilineus | Heteronemertea | Gibson (1995) | . | ICZN |
| Tenuiproboscis | Echinorhynchida | Amin (1985) | . | ICZN |
| Tenuisagitta | Aphragmophora | Bieri (1991) | Sagittidae. | ICZN |
| Tenuisentis | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Tenuitella | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Candeinidae. | ICZN |
| Tephrocactus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Tephrodornis | Passeriformes | Clements (2007) | . | ICZN |
| Tephroseris | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tephrosia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tephrozosterops | Passeriformes | Clements (2007) | . | ICZN |
| Tepidamorphus | Rhizobiales | Albuquerque et al. (2010) | . | ICNB |
| Tepidanaerobacter | Thermoanaerobacterales | Sekiguchi et al. (2006) | . | ICNB |
| Tepidibacter | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Tepidicella | Burkholderiales | França et al. (2006) | . | ICNB |
| Tepidimicrobium | Clostridiales | Slobodkin et al. (2006) | . | ICNB |
| Tepidimonas | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Tepidiphilus | Hydrogenophilales | Manaia et al. (2003) | . | ICNB |
| Tepualia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Tepuia | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Tepuianthus | Malvales | Mabberley (2008) | Thymelaeaceae. | ICBN |
| Tepuihyla | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Teramnus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Teranympha | Trichonymphida | Cepicka et al. (2010) | . | ICZN |
| Terasakiella | | Garrity et al. (2005); Wiese et al. (2009) | Domain Bacteria - Phylum Proteobacteria - Class Alphaproteobacteria; Possibly related to Kiloniellales. | ICNB |
| Terathopius | Falconiformes | Clements (2007) | . | ICZN |
| Teratodinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Teratolepis | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Teratophyllum | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Teratoscincus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Terebrospira | Apostomatida | Lynn (2008) | . | ICZN |
| Teredinibacter | Alteromonadales | Garrity et al. (2005) | . | ICNB |
| Terenotriccus | Passeriformes | Clements (2007) | . | ICZN |
| Terenura | Passeriformes | Clements (2007) | . | ICZN |
| Teretistris | Passeriformes | Clements (2007) | . | ICZN |
| Teretomonas | Glissomonadida | Howe et al. (2009) | . | ICZN |
| Teretrichodina | Mobilida | Lynn (2008) | . | ICZN |
| Teretrurus | Squamata | Vitt & Caldwell (2009) | Serpentes. Uropeltidae. | ICZN |
| Tergivelum | Helminthomorpha | Holland et al. (2009); Osborn et al. (2012) | Torquaratoridae. | ICZN |
| Terminalia | Myrtales | Mabberley (2008) | Combretaceae. | ICBN |
| Terminaliopsis | Myrtales | Mabberley (2008) | Combretaceae. | ICBN |
| Termitophrya | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Ternstroemia | Ericales | Mabberley (2008) | Pentaphylacaceae. | ICBN |
| Terpios | Hadromerida | Van Soest (2002) | . | ICZN |
| Terpsichore | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Terpsiphone | Passeriformes | Clements (2007) | . | ICZN |
| Terrabacter | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Terracoccus | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Terrapene | Testudinata | Vitt & Caldwell (2009) | Emydidae. | ICZN |
| Terrazoanthus | Zoanthidea | Reimer & Fujii (2010) | . | ICZN |
| Terribacillus | Bacillales | An et al. (2007) | . | ICNB |
| Terricirra | Sporadotrichida | Lynn (2008) | . | ICZN |
| Terriglobus | Acidobacteriales | Eichorst et al. (2007); Fukunaga et al. (2008) | . | ICNB |
| Terrimonas | Sphingobacteriales | Xie & Yokota (2006) | . | ICNB |
| Territricha | Sporadotrichida | Lynn (2008) | . | ICZN |
| Tersina | Passeriformes | Clements (2007) | . | ICZN |
| Tersonia | Brassicales | Mabberley (2008) | Gyrostemonaceae. | ICBN |
| Tesia | Passeriformes | Clements (2007) | . | ICZN |
| Tesnospira | Armophorida | Lynn (2008) | Later synonym of Metopus?. | ICZN |
| Tessaracoccus | Propionibacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Tessaria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tessellaria | Synurales | Kristiansen & Preisig (2001) | Synuraceae. | ICBN |
| Tesseranthelia | Alcyonacea | Bayer (1981) | Clavulariidae. | ICZN |
| Tesserogastria | Trachymedusae | Bouillon et al. (2006) | . | ICZN |
| Tessmannia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tessmanniacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Tessmannianthus | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Testechiniscus | Echiniscoidea | Kinchin (1994) | . | ICZN |
| Testudinella | Flosculariaceae | Segers (2002); Segers (2007) | . | ICZN |
| Testudo | Testudinata | Vitt & Caldwell (2009) | Testudinidae. | ICZN |
| Testudodinium | | Horiguchi et al. (2012) | . | ICBN |
| Testulea | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Testulorhiza | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rhabdamminidae. | ICZN |
| Tethocyathus | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Tethya | Hadromerida | Sarà (2002) | . | ICZN |
| Tethyastra | Hadromerida | Sarà (2002) | . | ICZN |
| Tethycometes | Hadromerida | Sarà (2002) | . | ICZN |
| Tethyopsis | Astrophorida | Uriz (2002) | . | ICZN |
| Tethyspira | Halichondrida | Van Soest et al. (2002) | . | ICZN |
| Tethytimea | Hadromerida | Sarà (2002) | . | ICZN |
| Tetilla | Spirophorida | Van Soest & Rützler (2002) | . | ICZN |
| Tetilla | Geraniales | Mabberley (2008) | Francoaceae. | ICBN |
| Tetmemena | Sporadotrichida | Lynn (2008) | . | ICZN |
| Tetmemorus | Desmidiales | Gontcharov (2008) | . | ICBN |
| Tetraberlinia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tetracanna | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tetracapsula | Malacovalvulida | Lom & Dyková (2006) | Junior synonym of Buddenbrockia. | ICZN |
| Tetracapsuloides | Malacovalvulida | Lom & Dyková (2006) | . | ICZN |
| Tetracarpaea | Saxifragales | Mabberley (2008) | Haloragaceae. | ICBN |
| Tetracentron | Trochodendrales | Mabberley (2008) | Trochodendraceae. | ICBN |
| Tetracera | Dilleniales | Mabberley (2008) | Dilleniaceae. | ICBN |
| Tetracerus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Tetrachaete | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tetrachlorella | Chlorellales | Pažoutová et al. (2010) | As Oocystis-clade or Oocystaceae. | ICBN |
| Tetrachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tetrachondra | Lamiales | Mabberley (2008) | Tetrachondraceae. | ICBN |
| Tetrachrysis | Phaeothamniales | Bailey et al. (1998) | . | ICBN |
| Tetrachyron | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetraclea | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Tetraclinis | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Tetracme | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Tetracoccus | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Tetracoscinodon | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Tetractinospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Tetractis | Actiniaria | Fautin et al. (2007) | Junior homonym, but no replacement name was published. | ICZN |
| Tetractomia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Tetracymbaliella | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Tetradactylus | Squamata | Vitt & Caldwell (2009) | Cordylidae. | ICZN |
| Tetradenia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Tetradiclis | Sapindales | Mabberley (2008) | Nitrariaceae. | ICBN |
| Tetradimorpha | Axomonadida | Bass et al. (2009); Yabuki et al. (2012) | . | ICZN |
| Tetradinium | Phytodiniales | Fensome et al. (1993) | . | ICBN |
| Tetradium | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Tetradymia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetraedriella | Mischococcales | Ettl (1978) | Tetraëdriella. | ICBN |
| Tetraedrophrya | Endogenida | Lynn (2008) | . | ICZN |
| Tetraedrospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Tetraena | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Tetragastris | Sapindales | Mabberley (2008) | Burseraceae. | ICBN |
| Tetragenococcus | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Tetragonia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Tetragonostomina | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Textulariidae. | ICZN |
| Tetragonotheca | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetrahymena | Tetrahymenida | Lynn (2008) | . | ICZN |
| Tetrakentron | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Tetraktis | Mischococcales | Ettl (1978) | . | ICBN |
| Tetralepis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tetralithoides | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Syracosphaerales ?. | ICBN |
| Tetralix | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Tetralocularia | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Tetralonche | Arthracanthida | Febvre et al. (2000) | . | ICZN |
| Tetralophozia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Tetramastigamoeba | Schizopyrenida | Patterson et al. (2000) | . | ICZN |
| Tetrameles | Cucurbitales | Mabberley (2008) | Datiscaceae. | ICBN |
| Tetrameraden | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Tetrameranthus | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Tetrameridionospinospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Tetramerista | Ericales | Mabberley (2008) | Tetrameristaceae. | ICBN |
| Tetramerium | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Tetramicra | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Tetramicra | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tetramitus | Schizopyrenida | Patterson et al. (2000) | . | ICZN |
| Tetramolopium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetramys | Heteronemertea | Gibson (1995); Kajihara et al. (2008) | . | ICZN |
| Tetramyxa | Plasmodiophorida | Cavalier-Smith (1993); Kirk et al. (2008) | . | ICZN |
| Tetranchyroderma | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Tetranema | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Tetranemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Tetraneuris | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetraneuronemertes | | Sundberg et al. (2007) | Domain Eucarya - Kingdom Animalia - Phylum Nemertea - Class Hoplonemertea - Subclass Monostilifera. Now checking. | ICZN |
| Tetranthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetrao | Galliformes | Clements (2007) | . | ICZN |
| Tetraogallus | Galliformes | Clements (2007) | . | ICZN |
| Tetraophasis | Galliformes | Clements (2007) | . | ICZN |
| Tetraotoporpa | Narcomedusae | Bouillon et al. (2006) | . | ICZN |
| Tetrapanax | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Tetraparma | Parmales | Booth & Marchant (1987) | . | ICBN |
| Tetrapathes | Antipatharia | Opresko (2004) | . | ICZN |
| Tetraperone | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tetraphidopsis | Ptychomniales | Goffinet et al. (2009) | . | ICBN |
| Tetraphis | Tetraphidales | Goffinet et al. (2009) | . | ICBN |
| Tetraphyllaster | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tetraphyllum | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Tetrapion | Phaeothamniales | Bailey et al. (1998) | . | ICBN |
| Tetraplandra | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Tetraplasandra | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Tetraplektron | Mischococcales | Ettl (1978) | . | ICBN |
| Tetrapleura | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tetrapleurodon | Petromyzontiformes | Nelson (2006) | . | ICZN |
| Tetraplodon | Splachnales | Goffinet et al. (2009) | . | ICBN |
| Tetrapocillon | Poecilosclerida | Hajdu & Lerner (2002) | . | ICZN |
| Tetrapogon | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tetrapollinia | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Tetrapoma | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tetraposthia | Acoela | Dörjes (1968) | . | ICZN |
| Tetrapterocarpon | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tetrapteron | Myrtales | Mabberley (2008) | Closely related to Camissonia. | ICBN |
| Tetrapterum | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Tetrapterys | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Tetrapyle | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Tetraralphia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Tetraria | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Tetrarrhena | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tetraselago | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Tetraselmis | Chlorodendrales | Moestrup (2000); Massjuk (2006) | . | ICBN |
| Tetrasida | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Tetrasiphon | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Tetrasiphon | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Tetrasphaera | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Tetraspidium | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Tetrasporopsis | | Bailey et al. (1998); Kai et al. (2008) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. Closely related to Chrysomeridales (Chrysomerophyceae). | ICBN |
| Tetrastemma | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Tetrastichium | Hookeriales | Goffinet et al. (2009) | . | ICBN |
| Tetrastigma | Vitales | Mabberley (2008) | Vitaceae. | ICBN |
| Tetrastylidium | Santalales | Mabberley (2008) | Erythropalaceae. | ICBN |
| Tetrasynandra | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Tetrataenium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tetrataxiella | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Globotextulariidae. | ICZN |
| Tetrataxis | Myrtales | Mabberley (2008) | Lythraceae. | ICBN |
| Tetrathamnion | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tetratheca | Oxalidales | Mabberley (2008) | Elaeocarpaceae. | ICBN |
| Tetrathiobacter | Burkholderiales | Ghosh et al. (2005); Gibello et al. (2009) | Later synonym of Advenella. | ICNB |
| Tetrathylacium | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Tetratoxum | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Tetratrichomastix | Honigbergiellida | Cepicka et al. (2010) | . | ICZN |
| Tetratrichomonas | Trichomonadida | Cepicka et al. (2010) | . | ICZN |
| Tetraulacium | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Tetrauronema | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Tetrax | Gruiformes | Clements (2007) | . | ICZN |
| Tetrazona | Aplousobranchia | Monniot & Monniot (1972); Kott (1998) | Junior synonym of Polycitor. | ICZN |
| Tetrazygia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tetreutreptia | Eutreptiales | Marin et al. (2003) | Synonymous to Eutreptiella. | ICBN |
| Tetrodontium | Tetraphidales | Goffinet et al. (2009) | . | ICBN |
| Tetroncium | Alismatales | Mabberley (2008) | Juncaginaceae. | ICBN |
| Tetrorchidium | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Tetrorchis | Trachymedusae | Bouillon et al. (2006) | . | ICZN |
| Tettigonospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Teuchocercus | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Teucridium | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Teucrium | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Teuscheria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Teuthophrys | Haptorida | Lynn (2008) | . | ICZN |
| Textularia | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Textulariidae. | ICZN |
| Textulariella | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Textulariellidae. | ICZN |
| Textularioides | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Textulariidae. | ICZN |
| Textulina | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Textulariidae. | ICZN |
| Teyleria | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Thaia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thailentadopsis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Thalamophaga | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hospitellidae. | ICZN |
| Thalamophyllia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Thalarctos | Carnivora | McKenna & Bell (1997); Wozencraft (2005) | Later synonym of Ursus. | ICZN |
| Thalassarche | Procellariiformes | Clements (2007) | . | ICZN |
| Thalasseus | Charadriiformes | Clements (2007) | . | ICZN |
| Thalassia | Alismatales | Mabberley (2008) | Hydrocharitaceae. | ICBN |
| Thalassianthus | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Thalassicolla | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thalassiomastix | Haptorida | Lynn (2008) | . | ICZN |
| Thalassobacillus | Bacillales | García et al. (2005) | . | ICNB |
| Thalassobacter | Rhodobacterales | Macián et al. (2005) | . | ICNB |
| Thalassobaculum | Rhodospirillales | Zhang et al. (2008) | . | ICNB |
| Thalassobius | Rhodobacterales | Arahal et al. (2005) | . | ICNB |
| Thalassocalyce | Thalassocalycida | Harbison & Madin (1982) | . | ICZN |
| Thalassochona | Cryptogemmida | Lynn (2008) | . | ICZN |
| Thalassococcus | Rhodobacterales | Lee et al. (2007) | . | ICNB |
| Thalassodendron | Alismatales | Mabberley (2008) | Cymodoceaceae. | ICBN |
| Thalassoica | Procellariiformes | Clements (2007) | . | ICZN |
| Thalassolampe | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thalassolituus | Oceanospirillales | Yakimov et al. (2004) | . | ICNB |
| Thalassomonas | Alteromonadales | Garrity et al. (2005) | . | ICNB |
| Thalassomyces | Thalassomycetales | Whisler (1990) | As ellobiopsids. | ICBN |
| Thalassomyxa | Aconchulinida | Bass et al. (2009) | . | ICZN |
| Thalassophis | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Thalassoplancta | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thalassornis | Anseriformes | Clements (2007) | . | ICZN |
| Thalassosphaera | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thalassospira | | Garrity et al. (2005); Wiese et al. (2009) | Domain Bacteria - Phylum Proteobacteria - Class Alphaproteobacteria; Possibly related to Kiloniellales. | ICNB |
| Thalassoxanthium | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thaleropia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Thalesius | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Thalia | Salpida | Godeaux (1998) | . | ICZN |
| Thalia | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Thalicola | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Thalictrum | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Thallassionemertes | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Amphiporidae. | ICZN |
| Thallochrysis | | Kristiansen & Preisig (2001) | Domain Eucarya - Kingdom Straminipila - Phylum Ochrophyta. | ICBN |
| Thallomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thalmannammina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ammosphaeroidinidae. | ICZN |
| Thalpomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thalpophila | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Thalurania | Apodiformes | Clements (2007) | . | ICZN |
| Thaminophyllum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thamnea | Bruniales | Mabberley (2008) | Bruniaceae. | ICBN |
| Thamniopsis | Hookeriales | Goffinet et al. (2009) | . | ICBN |
| Thamnistes | Passeriformes | Clements (2007) | . | ICZN |
| Thamnobryum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Thamnocalamus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thamnocharis | Lamiales | Mabberley (2008); Möller et al. (2011) | Gesneriaceae. Later synonym of Oreocharis. | ICBN |
| Thamnochortus | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Thamnoclonium | Cryptonemiales | Silva (2002); Schneider & Wynne (2007) | . | ICBN |
| Thamnodynastes | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Thamnolaea | Passeriformes | Clements (2007) | . | ICZN |
| Thamnomanes | Passeriformes | Clements (2007) | . | ICZN |
| Thamnomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thamnophilus | Passeriformes | Clements (2007) | . | ICZN |
| Thamnophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Thamnophyllis | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Thamnornis | Passeriformes | Clements (2007) | . | ICZN |
| Thamnosciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Thamnoseris | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thamnosma | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Thamnostoma | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Thamnostylus | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Thanatostrea | Labyrinthulales | Dick (2001); Kirk et al. (2008) | Not validly published?. | ICBN |
| Thapsia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Thaptomys | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Thaspium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Thauera | Rhodocyclales | Garrity et al. (2005) | . | ICNB |
| Thaumasianthes | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Thaumastochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thaumastoderma | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Thaumastura | Apodiformes | Clements (2007) | . | ICZN |
| Thaumatella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Thaumatocaryon | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Thaumatococcus | Zingiberales | Mabberley (2008) | Marantaceae. | ICBN |
| Thaumatodinium | Dinophysiales | Fensome et al. (1993) | . | ICBN |
| Thaumatomastix | Thaumatomonadida | Howe et al. (2011) | . | ICZN |
| Thaumatomonas | Thaumatomonadida | Howe et al. (2011) | . | ICZN |
| Thaumatophrya | Exogenida | Lynn (2008) | . | ICZN |
| Thaumatorhynchus | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Thaumatoscyphus | Stauromedusae | Kramp (1961); Larson & Fautin (1989) | Junior synonym of Manania. | ICZN |
| Thaurilens | Peridiniales | Fensome et al. (1993) | . | ICBN |
| Thecacineta | Exogenida | Lynn (2008) | . | ICZN |
| Thecacoris | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Thecadactylus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Thecadiniopsis | Gonyaulacales | Fensome et al. (1993) | . | ICBN |
| Thecadinium | Gonyaulacales | Fensome et al. (1993) | . | ICBN |
| Thecamoeba | Thecamoebida | Rogerson & Patterson (2000); Cavalier-Smith et al. (2004); Smirnov et al. (2011) | . | ICZN |
| Thecamonas | Apusomonadida | Cavalier-Smith & Chao (2010) | . | ICZN |
| Thecocarpus | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Thecochaos | | Rogerson & Patterson (2000); Cavalier-Smith et al. (2004); Smirnov et al. (2011) | Domain Eucarya - Phylum Amoebozoa - Subphylum Lobosa. | ICZN |
| Thecocodium | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Thecopsammia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Thecopus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thecorchus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Thecosphaera | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thecostele | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thedachloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Theileria | Piroplasmorida | Perkins et al. (2000) | . | ICZN |
| Thelactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Thelasis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thelepogon | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thelesperma | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thelethylax | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Thelia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Theligonum | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Thelionema | Asparagales | Mabberley (2008) | Hemerocallidaceae. | ICBN |
| Thelocactus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Theloderma | Anura | Vitt & Caldwell (2009) | Rhacophoridae. | ICZN |
| Thelogorgia | Alcyonacea | Bayer (1991) | Keroeididae. | ICZN |
| Thelohanellus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Thelohania | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Thelotornis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Thelymitra | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thelypodiopsis | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Thelypodium | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Thelypteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Thelyschista | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Themeda | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Themelium | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Themistoclesia | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Thenardia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Thenea | Astrophorida | Maldonado (2002) | . | ICZN |
| Theobroma | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Theocorythium | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Theodorella | Stolidobranchia | Monniot & Monniot (1972) | Styelidae. | ICZN |
| Theonella | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Theonellidae. | ICZN |
| Theophrasta | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Theopilium | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Theratromyxa | Aconchulinida | Bass et al. (2009) | . | ICZN |
| Thereianthus | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Theriophonum | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Theristicus | Ciconiiformes | Clements (2007) | . | ICZN |
| Thermacetogenium | Thermoanaerobacterales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Thermaerobacter | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Thermanaeromonas | Thermoanaerobacterales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Thermanaerovibrio | Synergistales | Garrity et al. (2005); Jumas-Bilak et al. (2007); Jumas-Bilak et al. (2009) | . | ICNB |
| Thermanemertes | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Emplectonematidae. | ICZN |
| Thermasporomyces | Propionibacteriales | Yabe et al. (2011); Ludwig et al. (2012) | Nocardioidaceae. | ICNB |
| Thermicanus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Thermincola | Clostridiales | Sokolova et al. (2005) | . | ICNB |
| Thermithiobacillus | Acidithiobacillales | Garrity et al. (2005) | . | ICNB |
| Thermoactinomyces | Bacillales | Garrity et al. (2005) | . | ICNB |
| Thermoactinospora | Streptosporangiales | Zhou et al. (2012) | . | ICNB |
| Thermoanaerobacter | Thermoanaerobacterales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Thermoanaerobacterium | Thermoanaerobacterales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Thermoanaerobium | Thermoanaerobacterales | Garrity et al. (2005); Wiegel (2009) | Later synonym of Thermoanaerobacter. | ICNB |
| Thermobacillus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Thermobifida | Streptosporangiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Thermobispora | | Garrity et al. (2005); Ludwig et al. (2012) | Domain Bacteria - Kingdom Bacteria - Phylum Actinobacteria - Class Actinobacteria. | ICNB |
| Thermobrachium | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Thermocatellispora | Streptosporangiales | Zhou et al. (2012) | . | ICNB |
| Thermochromatium | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thermocladium | Thermoproteales | Garrity et al. (2005) | . | ICNB |
| Thermococcoides | Thermotogales | Feng et al. (2010); Nunoura et al. (2010) | Later synonym of Kosmotoga. | ICNB |
| Thermococcus | Thermococcales | Garrity et al. (2005) | . | ICNB |
| Thermocrinis | Aquificales | Garrity et al. (2005) | . | ICNB |
| Thermocrispum | Pseudonocardiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Thermodesulfatator | Thermodesulfobacteriales | Moussard et al. (2004) | . | ICNB |
| Thermodesulfobacterium | Thermodesulfobacteriales | Garrity et al. (2005) | . | ICNB |
| Thermodesulfobium | Thermoanaerobacterales | Mori et al. (2003); Ludwig et al. (2009) | . | ICNB |
| Thermodesulforhabdus | Syntrophobacterales | Garrity et al. (2005) | . | ICNB |
| Thermodesulfovibrio | Nitrospirales | Garrity et al. (2005) | . | ICNB |
| Thermodiscus | Desulfurococcales | Garrity et al. (2005) | . | ICNB |
| Thermofilum | Thermoproteales | Garrity et al. (2005) | . | ICNB |
| Thermoflavimicrobium | Bacillales | Yoon et al. (2005) | . | ICNB |
| Thermogemmatispora | Thermogemmatisporales | Yabe et al. (2011) | . | ICNB |
| Thermogymnomonas | Picrophilales | Itoh et al. (2007) | . | ICNB |
| Thermohalobacter | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Thermohydrogenium | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Thermoleophilum | Thermoleophilales | Garrity et al. (2005); Reddy & Garcia-Pichel (2009); Ludwig et al. (2012) | . | ICNB |
| Thermolithobacter | Thermolithobacterales | Sokolova et al. (2007) | . | ICNB |
| Thermomicrobium | Thermomicrobiales | Garrity et al. (2005) | . | ICNB |
| Thermomonas | Xanthomonadales | Garrity et al. (2005) | . | ICNB |
| Thermomonospora | Streptosporangiales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Thermonema | | Garrity et al. (2005); Ludwig et al. (2011) | Domain Bacteria - Phylum Bacteroidetes - Class Cytophagia. | ICNB |
| Thermopalia | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Thermophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Thermoplasma | Picrophilales | Garrity et al. (2005) | . | ICNB |
| Thermopolyspora | Streptosporangiales | Goodfellow et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Thermoproteus | Thermoproteales | Garrity et al. (2005) | . | ICNB |
| Thermopsis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Thermosediminibacter | Thermoanaerobacterales | Lee et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Thermosinus | Selenomonadales | Sokolova et al. (2004); Marchandin et al. (2010) | . | ICNB |
| Thermosipho | Thermotogales | Garrity et al. (2005) | . | ICNB |
| Thermosphaera | Desulfurococcales | Garrity et al. (2005) | . | ICNB |
| Thermosporothrix | Ktedonobacterales | Yabe et al. (2010) | . | ICNB |
| Thermosulfidibacter | Aquificales | Nunoura et al. (2008) | . | ICNB |
| Thermosulfurimonas | Thermodesulfobacteriales | Slobodkin et al. (2012) | Under confirmation. | ICNB |
| Thermosyntropha | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Thermotalea | Clostridiales | Ogg & Patel (2009) | . | ICNB |
| Thermoterrabacterium | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Thermothrix | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Thermotoga | Thermotogales | Garrity et al. (2005) | . | ICNB |
| Thermovenabulum | Thermoanaerobacterales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Thermovibrio | Aquificales | Garrity et al. (2005) | . | ICNB |
| Thermovirga | Synergistales | Dahle & Birkeland (2006); Jumas-Bilak et al. (2007); Jumas-Bilak et al. (2009) | . | ICNB |
| Thermovorax | Thermoanaerobacterales | Mäkinen et al. (2009) | . | ICNB |
| Thermovum | Rhizobiales | Yabe et al. (2012) | . | ICNB |
| Thermus | Thermales | Garrity et al. (2005) | . | ICNB |
| Theropithecus | Primates | McKenna & Bell (1997) | . | ICZN |
| Theropogon | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Therorhodion | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Thescelocichla | Passeriformes | Clements (2007) | . | ICZN |
| Thesea | Alcyonacea | Bayer (1981) | Plexauridae. | ICZN |
| Thesidium | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Thesium | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Thesmophora | Lamiales | Mabberley (2008) | Stilbaceae. | ICBN |
| Thespesia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Thespidium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thespis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thetys | Salpida | Godeaux (1998) | . | ICZN |
| Thevenotia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thevetia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Thibaudia | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Thigmocoma | Pleuronematida | Lynn (2008) | . | ICZN |
| Thigmogaster | Chlamydodontida | Lynn (2008) | . | ICZN |
| Thigmokeronopsis | Urostylida | Lynn (2008) | . | ICZN |
| Thigmophrya | Philasterida | Lynn (2008) | . | ICZN |
| Thigmostrombidium | Strombidiida | Lynn (2008) | . | ICZN |
| Thigmozoon | Philasterida | Lynn (2008) | . | ICZN |
| Thilachium | Brassicales | Mabberley (2008) | Capparaceae. | ICBN |
| Thiloa | Myrtales | Mabberley (2008) | Combretaceae. | ICBN |
| Thinicola | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Thinocorus | Charadriiformes | Clements (2007) | . | ICZN |
| Thinopyrum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thinornis | Charadriiformes | Clements (2007) | . | ICZN |
| Thinouia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Thioalbus | | Park et al. (2011) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria. | ICNB |
| Thioalkalibacter | Chromatiales | Banciu et al. (2008) | Possibly later synonym of Halothiobacillus. | ICNB |
| Thioalkalicoccus | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thioalkalimicrobium | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Thioalkalispira | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thioalkalivibrio | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiobaca | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiobacillus | Hydrogenophilales | Garrity et al. (2005) | . | ICNB |
| Thiobacter | | Hirayama et al. (2005) | Domain Bacteria - Phylum Proteobacteria - Class Betaproteobacteria. | ICNB |
| Thiobacterium | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Thiocapsa | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiochaete | Nostocales | Yamagishi (2007) | . | ICBN |
| Thioclava | Rhodobacterales | Sorokin et al. (2005) | . | ICNB |
| Thiococcus | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiocystis | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiodictyon | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiofaba | Chromatiales | Mori & Suzuki (2008) | . | ICNB |
| Thioflavicoccus | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiohalobacter | Chromatiales | Sorokin et al. (2010) | . | ICNB |
| Thiohalocapsa | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiohalomonas | | Sorokin et al. (2007) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria . | ICNB |
| Thiohalophilus | Chromatiales | Sorokin et al. (2007); Mori et al. (2011) | . | ICNB |
| Thiohalorhabdus | | Sorokin et al. (2008) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria. | ICNB |
| Thiohalospira | Chromatiales | Sorokin et al. (2008) | . | ICNB |
| Thiolamprovum | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiomargarita | Thiotrichales | Schulz & Jørgensen (2005) | . | ICNB |
| Thiomicrospira | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Thiomonas | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Thiopedia | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiophaeococcus | Chromatiales | Kumar et al. (2008) | . | ICNB |
| Thioploca | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Thioprofundum | Chromatiales | Takai et al. (2010); Mori et al. (2011) | . | ICNB |
| Thioreductor | Campylobacterales | Nakagawa et al. (2005) | . | ICNB |
| Thiorhodococcus | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiorhodospira | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiorhodovibrio | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiospira | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Thiospirillum | Chromatiales | Garrity et al. (2005) | . | ICNB |
| Thiothrix | Thiotrichales | Garrity et al. (2005) | . | ICNB |
| Thiovirga | Chromatiales | Ito et al. (2005) | . | ICNB |
| Thiovulum | Campylobacterales | Garrity et al. (2005) | . | ICNB |
| Thiseltonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thismia | Dioscoreales | Mabberley (2008) | Burmanniaceae. | ICBN |
| Thladiantha | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Thlaspi | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Thlypopsis | Passeriformes | Clements (2007) | . | ICZN |
| Thogsennia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tholoarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Tholosina | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hemisphaeramminidae. | ICZN |
| Tholospyris | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Tholostaurus | Spumellaria | Anderson et al. (2000) | . | ICZN |
| Thomandersia | Lamiales | Mabberley (2008) | Thomandersiaceae. | ICBN |
| Thomasia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Thomasomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thomomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thompsodinium | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae - Subclass Peridiniphycidae. | ICBN |
| Thompsonella | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Thomsenella | Acanthoecida | Leadbeater & Thomsen (2000); Özdikmen (2009) | Substitution name for Platypleura. | ICZN |
| Thonningia | Santalales | Mabberley (2008) | Balanophoraceae. | ICBN |
| Thoopterus | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Thoosa | Hadromerida | Rützler (2002) | . | ICZN |
| Thoracocarpus | Pandanales | Mabberley (2008) | Cyclanthaceae. | ICBN |
| Thoracodinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Thoracosphaera | Thoracosphaerales | Fensome et al. (1993) | . | ICBN |
| Thorea | Thoreales | Schneider & Wynne (2007) | . | ICBN |
| Thoreauea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Thorecta | Dictyoceratida | Cook & Bergquist (2002) | . | ICZN |
| Thorectandra | Dictyoceratida | Cook & Bergquist (2002) | . | ICZN |
| Thorectaxia | Dictyoceratida | Cook & Bergquist (2002) | . | ICZN |
| Thorius | Caudata | Vitt & Caldwell (2009) | Plethodontidae. | ICZN |
| Thorncroftia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Thornea | Malpighiales | Mabberley (2008) | Hypericaceae. | ICBN |
| Thoropa | Anura | Vitt & Caldwell (2009) | Cycloramphidae. | ICZN |
| Thorsellia | Enterobacteriales | Kämpfer et al. (2006) | . | ICNB |
| Thottea | Piperales | Mabberley (2008) | Aristolochiaceae. | ICBN |
| Thouinia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Thouinidium | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Thrasops | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Thrasya | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thrasyopsis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thraupis | Passeriformes | Clements (2007) | . | ICZN |
| Thraustochytrium | Thraustochytriales | Dick (2001); Kirk et al. (2008) | Thraustochytriaceae. | ICBN |
| Thraustotheca | Saprolegniales | Dick (2001); Kirk et al. (2008) | Saprolegniaceae. | ICBN |
| Threlkeldia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Threnetes | Apodiformes | Clements (2007) | . | ICZN |
| Threskiornis | Ciconiiformes | Clements (2007) | . | ICZN |
| Thrichomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thrinacophora | Poecilosclerida | Hooper (2002) | . | ICZN |
| Thrinax | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Thripadectes | Passeriformes | Clements (2007) | . | ICZN |
| Thripophaga | Passeriformes | Clements (2007) | . | ICZN |
| Thrixspermum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thrombus | Astrophorida | Uriz (2002) | . | ICZN |
| Thryallis | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Thryomanes | Passeriformes | Clements (2007) | . | ICZN |
| Thryonomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Thryorchilus | Passeriformes | Clements (2007) | . | ICZN |
| Thryothorus | Passeriformes | Clements (2007) | . | ICZN |
| Thrypticotrochus | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Thryptomene | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Thuarea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thuiaria | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Thuidiopsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Thuidium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Thuja | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Thujopsis | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Thulinia | Parachela | Kinchin (1994) | . | ICZN |
| Thulinia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thunbergia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Thunbergianthus | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Thunia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thurammina | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Saccamminidae. | ICZN |
| Thuretella | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Thuretellopsis | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Thuretia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Thuricola | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Thurnia | Poales | Mabberley (2008) | Thurniaceae. | ICBN |
| Thurovia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thurstonia | Thigmotrichida | Lynn (2008) | . | ICZN |
| Thurya | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Thuspeinanta | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Thylacinus | Dasyuromorphia | Groves (2005) | Recently extinct. | ICZN |
| Thylacopteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Thylacospermum | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Thylakidium | Bursariomorphida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Thylamys | Ameridelphia | McKenna & Bell (1997) | . | ICZN |
| Thylogale | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Thymbra | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Thymelaea | Malvales | Mabberley (2008) | Thymelaeaceae. | ICBN |
| Thymophylla | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thymopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Thymosia | Chondrosida | Boury-Esnault (2002) | . | ICZN |
| Thymosiopsis | Chondrosida | Boury-Esnault (2002) | . | ICZN |
| Thymus | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Thyridachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thyridocalyx | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Thyridolepis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thyrocarpus | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Thyrophylax | Philasterida | Lynn (2008) | . | ICZN |
| Thyroptera | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Thyroscyphus | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Thyroscypoides | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Thyrsanthemum | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Thyrsanthera | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Thyrsodium | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Thyrsopteris | Cyatheales | Christenhusz et al. (2011) | . | ICBN |
| Thyrsosalacia | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Thyrsostachys | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thysananthus | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Thysanocarpus | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Thysanoglossa | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Thysanolaena | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Thysanomorpha | Haptorida | Lynn (2008) | . | ICZN |
| Thysanosoria | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Thysanostemon | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Thysanostigma | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Thysanostoma | Rhizostomeae | Kramp (1961) | . | ICZN |
| Thysanotus | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Thyselium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tianschaniella | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Tiarella | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Tiaricodon | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Tiarina | Prorodontida | Lynn (2008) | . | ICZN |
| Tiarinella | Prorodontida | Lynn (2008) | . | ICZN |
| Tiaris | Passeriformes | Clements (2007) | . | ICZN |
| Tiarophora | | Schneider & Wynne (2007) | . | ICBN |
| Tiaropsidium | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tiaropsis | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tibitin | Stolidobranchia | Monniot (2001) | Styelidae. | ICZN |
| Tibouchina | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tibouchinopsis | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tichocarpus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Tichodroma | Passeriformes | Clements (2007) | . | ICZN |
| Tickellia | Passeriformes | Clements (2007) | . | ICZN |
| Ticodendron | Fagales | Mabberley (2008) | Ticodendraceae. | ICBN |
| Ticoglossum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ticorea | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Tidestromia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Tieghemella | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Tietkensia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tiffaniella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tigridia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Tigriornis | Ciconiiformes | Clements (2007) | . | ICZN |
| Tigrisoma | Ciconiiformes | Clements (2007) | . | ICZN |
| Tijuca | Passeriformes | Clements (2007) | . | ICZN |
| Tikvahiella | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Tilesia | Actiniaria | Fautin et al. (2007) | Junior homonym, but no replacement name was published. | ICZN |
| Tilesia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tilia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Tiliacora | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Tiliqua | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Tillandsia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Tillina | Colpodida | Foissner et al. (2011) | . | ICZN |
| Tilmatura | Apodiformes | Clements (2007) | . | ICZN |
| Tima | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Timalia | Passeriformes | Clements (2007) | . | ICZN |
| Timea | Hadromerida | Sarà (2002) | . | ICZN |
| Timeliopsis | Passeriformes | Clements (2007) | . | ICZN |
| Timmia | Timmiales | Goffinet et al. (2009) | . | ICBN |
| Timmiella | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Timoides | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Timon | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Timonius | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Timotimius | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Timspurckia | Porphyridiales | Yang et al. (2010) | . | ICBN |
| Tina | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tinadendron | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tinamotis | Tinamiformes | Clements (2007) | . | ICZN |
| Tinamus | Tinamiformes | Clements (2007) | . | ICZN |
| Tinantia | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Tindallia | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Tinerfe | Cydippida | Harbison & Madin (1982) | . | ICZN |
| Tinnea | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Tinogullmia | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Tinomiscium | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Tinophodella | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Candeinidae. | ICZN |
| Tinopsis | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tinospora | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Tintinnabularia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tintinnidium | Tintinnida | Lynn (2008) | . | ICZN |
| Tintinnophagus | | Coats et al. (2010) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Dinozoa - Class Dinophyceae. | ICBN |
| Tintinnopsis | Tintinnida | Lynn (2008) | . | ICZN |
| Tintinnus | Tintinnida | Lynn (2008) | . | ICZN |
| Tintinospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Tiparraria | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tiphotrocha | Trochamminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trochamminidae. | ICZN |
| Tipuana | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tipularia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tipulocystis | Neogregarinorida | Perkins et al. (2000) | . | ICZN |
| Tiputinia | Dioscoreales | Mabberley (2008) | Thismiaceae. | ICBN |
| Tiquilia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Tirania | Brassicales | Mabberley (2008) | Resedaceae. | ICBN |
| Tirpitzia | Malpighiales | Mabberley (2008) | Linaceae. | ICBN |
| Tisonia | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Tisserantiella | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Tissierella | Clostridiales | Garrity et al. (2005) | . | ICNB |
| Tistlia | Rhodospirillales | Díaz-Cárdenas et al. (2010) | . | ICNB |
| Tistrella | Rhodospirillales | Garrity et al. (2005) | . | ICNB |
| Titanideum | Alcyonacea | Bayer (1981) | Anthothelidae. | ICZN |
| Titaniloricus | Nanaloricida | Heiner & Kristensen (2009) | . | ICZN |
| Titanoderma | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Titanophora | Nemastomatales | Schneider & Wynne (2007) | . | ICBN |
| Titanophycus | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Titanopsis | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Titanotrichum | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Tithonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tittmannia | Bruniales | Mabberley (2008) | Bruniaceae. | ICBN |
| Tityra | Passeriformes | Clements (2007) | . | ICZN |
| Tjalfiella | Platyctenida | Harbison & Madin (1982) | . | ICZN |
| Tlacuatzin | Didelphimorphia | Gardner (2005) | . | ICZN |
| Tlalocohyla | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Tmesipteris | Psilotales | Christenhusz et al. (2011) | . | ICBN |
| Tmetothylacus | Passeriformes | Clements (2007) | . | ICZN |
| Tobagoa | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tocantinia | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Tockus | Coraciiformes | Clements (2007) | . | ICZN |
| Tococa | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tocoyena | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Todaroa | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Toddalia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Todea | Osmundales | Christenhusz et al. (2011) | . | ICBN |
| Todiramphus | Coraciiformes | Clements (2007) | . | ICZN |
| Todirostrum | Passeriformes | Clements (2007) | . | ICZN |
| Todus | Coraciiformes | Clements (2007) | . | ICZN |
| Toechima | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Toeplitzella | Alcyonacea | Bayer (1981); Bayer & Grasshoff (1994) | Junior synonym of Ctenocella. | ICZN |
| Tofieldia | Alismatales | Mabberley (2008) | Tofieldiaceae. | ICBN |
| Togula | | Jørgensen et al. (2004) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Dinozoa - Class Dinophyceae. | ICBN |
| Toiyabea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tokidadendron | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tokidaea | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tokophrya | Endogenida | Lynn (2008) | . | ICZN |
| Tokophryopsis | Endogenida | Lynn (2008) | . | ICZN |
| Tokudaia | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tolmiea | Saxifragales | Mabberley (2008) | Saxifragaceae. | ICBN |
| Tolmomyias | Passeriformes | Clements (2007) | . | ICZN |
| Toloxis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Tolpis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Toluca | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tolumnia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tolumonas | Aeromonadales | Garrity et al. (2005) | . | ICNB |
| Tolypanthus | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Tolypella | Charales | McCourt et al. (1999) | . | ICBN |
| Tolypeutes | Xenarthra | McKenna & Bell (1997) | . | ICZN |
| Tolypiocladia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tolypothrix | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Tomaculoides | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glandulinidae. | ICZN |
| Tomanthera | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Tomentaurum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tomentypnum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Tomistoma | Crocodylia | Vitt & Caldwell (2009) | Gavialidae. | ICZN |
| Tomitella | Corynebacteriales | Katayama et al. (2010); Ludwig et al. (2012) | Tsukamurellaceae. | ICNB |
| Tommasinia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tomodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tomopeas | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Tomophyllum | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Tomopterna | Anura | Vitt & Caldwell (2009) | Pyxicephalidae. | ICZN |
| Tomzanonia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tonatia | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Tonella | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Tonestus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tongoloa | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tonina | Poales | Mabberley (2008) | Eriocaulaceae. | ICBN |
| Tononemertes | Pelagica | Gibson (1995) | . | ICZN |
| Tontelea | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Tontonia | Strombidiida | Lynn (2008) | . | ICZN |
| Toona | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Topaza | Apodiformes | Clements (2007) | . | ICZN |
| Topobea | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Topsentia | Halichondrida | Erpenbeck & Van Soest (2002) | . | ICZN |
| Tordyliopsis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tordylium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Torenia | Lamiales | Mabberley (2008) | Linderniaceae. | ICBN |
| Toretammina | Trochamminida | Kaminski (2000) | Toretammininae, Trochamminacea. | ICZN |
| Torgos | Falconiformes | Clements (2007) | . | ICZN |
| Torilis | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tornabenea | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Torodinium | Gymnodiniales | Fensome et al. (1993) | . | ICBN |
| Torogregarina | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Toronia | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Torpedo | Torpediniformes | Nelson (2006) | . | ICZN |
| Torquarator | Helminthomorpha | Holland et al. (2005) | Torquaratoridae. | ICZN |
| Torralbasia | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Torreornis | Passeriformes | Clements (2007) | . | ICZN |
| Torresina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Discorbinellidae. | ICZN |
| Torreya | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Torreyochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Torricellia | Apiales | Mabberley (2008) | Torricelliaceae. | ICBN |
| Tortella | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Tortoplectella | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Tortoplectellidae. | ICZN |
| Tortuella | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tortula | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Tortus | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Torulumbonina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nodosariidae. | ICZN |
| Tosaia | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Tosaiidae. | ICZN |
| Tottonia | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Touchardia | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Touit | Psittaciformes | Clements (2007) | . | ICZN |
| Toulicia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tourneuxia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tournonia | Caryophyllales | Mabberley (2008) | Basellaceae. | ICBN |
| Touroulia | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Tourrettia | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Toussaintia | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Touwia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Touwiodendron | Hypnodendrales | Goffinet et al. (2009) | . | ICBN |
| Tovaria | Brassicales | Mabberley (2008) | Tovariaceae. | ICBN |
| Tovarochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tovellia | | Lindberg et al. (2005) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Dinozoa - Class Dinophyceae. Now checking. | ICBN |
| Tovomita | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Tovomitidium | Malpighiales | Mabberley (2008) | Guttiferae. | ICBN |
| Townsendia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Townsonia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Toxicocalamus | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Toxicoscordion | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Toxisarcon | Allogromiida | Kaminski (2008) | Closely related to Cylindrogullmia and Gloiogullmia. | ICZN |
| Toxochona | Exogemmida | Lynn (2008) | . | ICZN |
| Toxocytis | Piroplasmorida | Perkins et al. (2000) | . | ICZN |
| Toxodinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Toxoglugea | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Toxoplasma | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Toxopsis | Nostocales | Lamprinou et al. (2012) | . | ICBN |
| Toxorhamphus | Passeriformes | Clements (2007) | . | ICZN |
| Toxosiphon | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Toxospora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Toxostoma | Passeriformes | Clements (2007) | . | ICZN |
| Toxothrix | | Garrity et al. (2005); Ludwig et al. (2011) | Domain Bacteria - Phylum Bacteroidetes - Class Cytophagia. | ICNB |
| Tozzia | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Trabacellula | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Trabrooksia | Physarales | Martin et al. (1983); Yamamoto (1998); Lado (2001); Poulain et al. (2011) | Probably a later synonym of Dydimium (Martin et al., 1983; Lado, 2001), but some authors accepted its generic status (Yamamoto, 1998; Poulain et al., 2011). | ICBN |
| Trabulsiella | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Trachelanthus | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Tracheleuglypha | Euglyphida | Meisterfeld (2000) | . | ICZN |
| Trachelium | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Trachelius | Haptorida | Lynn (2008) | . | ICZN |
| Trachelocerca | Protostomatida | Lynn (2008) | . | ICZN |
| Trachelochaeta | Stichotrichida | Lynn (2008) | . | ICZN |
| Trachelocorythion | Euglyphida | Meisterfeld (2000) | . | ICZN |
| Trachelolophos | Protostomatida | Lynn (2008) | . | ICZN |
| Trachelomonas | Euglenales | Leedale (1967); Leedale (2000); Marin et al. (2003); Brosnan et al. (2005) | . | ICBN |
| Trachelophyllum | Haptorida | Lynn (2008) | . | ICZN |
| Tracheloptychus | Squamata | Vitt & Caldwell (2009) | Cordylidae. | ICZN |
| Tracheloraphis | Protostomatida | Lynn (2008) | . | ICZN |
| Trachelospermum | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Trachelostyla | Sporadotrichida | Lynn (2008) | . | ICZN |
| Trachelotractus | Haptorida | Lynn (2008) | . | ICZN |
| Trachemys | Testudinata | Vitt & Caldwell (2009) | Emydidae. | ICZN |
| Trachipleistophora | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Trachischium | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Trachops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Trachyandra | Asparagales | Mabberley (2008) | Asphodelaceae. | ICBN |
| Trachyboa | Squamata | Vitt & Caldwell (2009) | Serpentes. "Tropidophiidae". | ICZN |
| Trachycalymma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Trachycarpidium | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Trachycarpus | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Trachycaulus | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Trachycephalus | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Trachychloron | Mischococcales | Ettl (1978) | . | ICBN |
| Trachycladiella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trachycladus | Hadromerida | Hooper & Van Soest (2002) | . | ICZN |
| Trachycystis | Bryales | Goffinet et al. (2009) | . | ICBN |
| Trachycystis | Mischococcales | Ettl (1978); Silva (1979) | Later homonym, but probably no substitute name has been published. | ICBN |
| Trachydiscus | Mischococcales | Ettl (1978) | . | ICBN |
| Trachydium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Trachylejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Trachylepis | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Trachyloma | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trachymene | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Trachyodontium | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Trachyphonus | Piciformes | Clements (2007) | . | ICZN |
| Trachyphyllia | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Trachyphyllum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trachypithecus | Primates | Groves (2005) | . | ICZN |
| Trachypodopsis | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trachypogon | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trachypteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Trachypus | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trachys | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trachyspermum | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Trachysphaera | Pythiales | Dick (2001); Kirk et al. (2008) | Pythiaceae. | ICBN |
| Trachystemon | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Trachystigma | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Trachystoma | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Trachystylis | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Trachyteleia | Hadromerida | Boury-Esnault (2002) | . | ICZN |
| Trachythecium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trachythela | Alcyonacea | Bayer (1981) | Clavulariidae. | ICZN |
| Trachyxiphium | Hookeriales | Goffinet et al. (2009) | . | ICBN |
| Tractocopevodia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Tracyina | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tradescantia | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Traganopsis | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Traganum | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Tragelaphus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Tragia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Tragiella | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Tragopan | Galliformes | Clements (2007) | . | ICZN |
| Tragopogon | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tragulus | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Tragus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trailliaedoxa | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Trajectura | Echinorhynchida | Pichelin & Cribb (2001) | Transvenidae. | ICZN |
| Tranquillimonas | Rhodobacterales | Harwati et al. (2008) | . | ICNB |
| Transberingia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Transvena | Echinorhynchida | Pichelin & Cribb (2001) | Transvenidae. | ICZN |
| Trapa | Myrtales | Mabberley (2008) | Lythraceae. | ICBN |
| Trapella | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Trapelus | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Trattinnickia | Sapindales | Mabberley (2008) | Burseraceae. | ICBN |
| Traubia | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Traumatiophtora | Apostomatida | Lynn (2008) | . | ICZN |
| Traunsteinera | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Traustedtia | Salpida | Godeaux (1998) | . | ICZN |
| Trautvetteria | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Trebouxia | Trebouxiales | Friedl (1995) | . | ICBN |
| Treculia | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Tregellasia | Passeriformes | Clements (2007) | . | ICZN |
| Tregoubovia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Treichelia | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Trema | Rosales | Mabberley (2008) | Cannabaceae. | ICBN |
| Tremacanthus | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Tremacron | Lamiales | Mabberley (2008); Möller et al. (2011) | Gesneriaceae. Later synonym of Oreocharis. | ICBN |
| Tremandra | Oxalidales | Mabberley (2008) | Elaeocarpaceae. | ICBN |
| Tremarctos | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Trematocarpus | Plocamiales | Schneider & Wynne (2007) | . | ICBN |
| Trematodon | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Trematolobelia | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Trematophragmoides | Lituolida | Kaminski (2000) | Haplophragmoididae. | ICZN |
| Trematosoma | Endogenida | Lynn (2008) | . | ICZN |
| Trematotrochus | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Trembleya | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tremula | Tremulida | Howe et al. (2011) | . | ICZN |
| Tremulina | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Trepadonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trepocarpus | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Trepomonas | Diplomonadida | Brugerolle & Lee (2000) | . | ICZN |
| Treponema | Spirochaetales | Garrity et al. (2005) | . | ICNB |
| Treron | Columbiformes | Clements (2007) | . | ICZN |
| Tresanthera | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tretanorhinus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tretioscincus | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Tretocalyx | Hexactinosida | Reiswig (2002) | . | ICZN |
| Tretochone | Hexactinosida | Reiswig & Wheeler (2002) | . | ICZN |
| Tretodictyum | Hexactinosida | Reiswig (2002) | . | ICZN |
| Tretomphaloides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rosalinidae. | ICZN |
| Tretomphalus | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rosalinidae. | ICZN |
| Tretopleura | Aulocalycoida | Reiswig (2002) | . | ICZN |
| Treubia | Treubiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Treutlera | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Trevesia | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Trevoa | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Trevoria | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Triactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Triadenum | Malpighiales | Mabberley (2008) | Hypericaceae. | ICBN |
| Triadica | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Triadinium | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Triadinium | Gonyaulacales | Dodge & Lee (2000) | . | ICBN |
| Triadodaphne | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Triadopathes | Antipatharia | Opresko (2006) | . | ICZN |
| Triaenamoeba | Dactylopodida | Rogerson & Patterson (2000); Smirnov et al. (2005) | Vexilliferidae. | ICZN |
| Triaenodon | Carcharhiniformes | Nelson (2006) | . | ICZN |
| Triaenophora | Lamiales | Mabberley (2008); Schäferhoff et al. (2010) | Closely related to Orobanchaceae. | ICBN |
| Triaenops | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Triainolepis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Triakis | Carcharhiniformes | Nelson (2006) | . | ICZN |
| Trianaea | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Triandrophyllum | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Triangula | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Triangulamyxa | Bivalvulida | Azevedo et al. (2005) | . | ICZN |
| Triangulomonas | | Keedale (1967) | Sphenomonadales or Heteronematales. | ICBN |
| Trianoptiles | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Trianthema | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Triaspis | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Tribeles | Escalloniales | Mabberley (2008) | Escalloniaceae. | ICBN |
| Tribolium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tribolonotus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Tribonanthes | Commelinales | Mabberley (2008) | Haemodoraceae. | ICBN |
| Tribonema | Tribonematales | Ettl (1978) | . | ICBN |
| Tribrachium | Astrophorida | Uriz (2002) | . | ICZN |
| Tribulocarpus | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Tribulopis | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Tribulus | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Tricalysia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Tricardia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Tricarpelema | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Tricaudalia | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Triceraspyris | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Triceratella | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Triceratolepidophis | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Triceratorhynchus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tricercomitus | Honigbergiellida | Cepicka et al. (2010) | . | ICZN |
| Tricerma | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Trichadenia | Malpighiales | Mabberley (2008) | Achariaceae. | ICBN |
| Trichamoeba | Euamoebida | Rogerson & Patterson (2000); Smirnov et al. (2005) | . | ICZN |
| Trichantha | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Trichanthemis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichanthera | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Trichanthodium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichasterina | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Trichastoma | Passeriformes | Clements (2007) | . | ICZN |
| Trichaulia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Trichechus | Sirenia | McKenna & Bell (1997) | . | ICZN |
| Trichia | Trichiales | Yamamoto (1998) | . | ICBN |
| Trichidium | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Trichilia | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Trichixos | Passeriformes | Clements (2007) | . | ICZN |
| Trichlora | Asparagales | Mabberley (2008) | Alliaceae. | ICBN |
| Trichloris | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trichlorobacter | Desulfuromonales | Garrity et al. (2005) | . | ICNB |
| Trichobatrachus | Anura | Vitt & Caldwell (2009) | Arthroleptidae. | ICZN |
| Trichocalyx | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Trichocephalus | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Trichocerca | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Trichoceros | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trichochona | Cryptogemmida | Lynn (2008) | . | ICZN |
| Trichocichla | Passeriformes | Clements (2007) | . | ICZN |
| Trichocladus | Saxifragales | Mabberley (2008) | Hamamelidaceae. | ICBN |
| Trichocline | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichococcus | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Trichocolea | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Trichocoleopsis | Ptilidiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Trichocoleus | Pseudanabaenales | Hoffmann et al. (2005) | . | ICBN |
| Trichocoronis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichocoryne | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichocovina | | Cepicka et al. (2010) | Domain Eucarya - Phylum Metamonada - Superclass Parabasalia. | ICZN |
| Trichoctosporea | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Trichodere | Passeriformes | Clements (2007) | . | ICZN |
| Trichodesma | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Trichodesmium | Oscillatoriales | Hoffmann et al. (2005) | . | ICBN |
| Trichodiadema | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Trichodina | Mobilida | Lynn (2008) | . | ICZN |
| Trichodinella | Mobilida | Lynn (2008) | . | ICZN |
| Trichodinopsis | Mobilida | Lynn (2008) | Earlier synonym of Urceolaria?. | ICZN |
| Trichodon | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Trichodoxa | Mobilida | Lynn (2008) | . | ICZN |
| Trichoduboscqia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Trichogloea | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Trichogloeopsis | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Trichoglossus | Psittaciformes | Clements (2007) | . | ICZN |
| Trichoglottis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trichogonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichogoniopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichogorgia | Alcyonacea | Bayer (1981) | Chrysogorgiidae. | ICZN |
| Trichogyne | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichogypsia | Baerida | Borojevic et al. (2002) | . | ICZN |
| Trichohyalus | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trichohyalidae. | ICZN |
| Tricholaema | Piciformes | Clements (2007) | . | ICZN |
| Tricholaena | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tricholaser | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Tricholepidium | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Tricholepis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tricholestes | Passeriformes | Clements (2007) | . | ICZN |
| Trichomanes | Hymenophyllales | Christenhusz et al. (2011) | . | ICBN |
| Trichomitopsis | Trichomonadida | Cepicka et al. (2010) | . | ICZN |
| Trichomitus | Hypotrichomonadida | Cepicka et al. (2010) | . | ICZN |
| Trichomonas | Trichomonadida | Cepicka et al. (2010) | . | ICZN |
| Trichomonoides | Trichomonadida | Cepicka et al. (2010) | . | ICZN |
| Trichoneura | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trichonosema | Microsporida | Canning et al. (2002) | . | ICZN |
| Trichonympha | Trichonymphida | Cepicka et al. (2010) | . | ICZN |
| Trichopetalum | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Trichophorum | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Trichophrya | Endogenida | Lynn (2008) | . | ICZN |
| Trichopilia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trichoplax | Placozoida | Grell (1982); Brusca & Brusca (2003) | . | ICZN |
| Trichopodiella | Dysteriida | Lynn (2008) | . | ICZN |
| Trichopteryx | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trichoptilium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichopus | Dioscoreales | Mabberley (2008) | Dioscoreaceae. | ICBN |
| Trichorhynchus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Trichormus | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Trichosacme | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Trichosalpinx | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trichosanchezia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Trichosandra | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Trichosanthes | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Trichoschoenus | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Trichoscypha | Sapindales | Mabberley (2008) | Anacardiaceae. | ICBN |
| Trichospermum | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Trichosphaerium | Trichosida | Rogerson & Patterson (2000); Cavalier-Smith et al. (2004); Tekle et al. (2008) | . | ICZN |
| Trichospira | Tetrahymenida | Lynn (2008) | . | ICZN |
| Trichospira | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trichostachys | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Trichosteleum | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trichostema | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Trichostephanus | Malpighiales | Mabberley (2008) | Achariaceae. | ICBN |
| Trichostigma | Caryophyllales | Mabberley (2008) | Phytolaccaceae. | ICBN |
| Trichostomum | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Trichosurus | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Trichotaxis | Urostylida | Lynn (2008) | . | ICZN |
| Trichotemnoma | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Trichothraupis | Passeriformes | Clements (2007) | . | ICZN |
| Trichotokara | Eugregarinorida | Rueckert & Leander (2010) | . | ICZN |
| Trichotolinum | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Trichotosia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trichotria | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Trichotuzetia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Trichuriella | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Trichurispora | Eugregarinorida | Clopton et al. (2008) | . | ICZN |
| Trichydra | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Trichys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Triclaria | Psittaciformes | Clements (2007) | . | ICZN |
| Tricleocarpa | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Tricliceras | Malpighiales | Mabberley (2008) | Passifloraceae. | ICBN |
| Triclisia | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Tricnidactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Tricomaria | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Tricornia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Tricoronella | Urostylida | Lynn (2008) | . | ICZN |
| Tricoryne | Asparagales | Mabberley (2008) | Hemerocallidaceae. | ICBN |
| Tricostularia | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Tricyclandra | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Tricyclusa | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Tricyrtis | Liliales | Mabberley (2008) | Liliaceae. | ICBN |
| Tricystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Tridactyle | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tridactylina | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tridax | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tridens | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tridentea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tridesmostemon | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Trididemnum | Aplousobranchia | Monniot & Monniot (1972); Monniot (2001) | Didemnidae. | ICZN |
| Tridimeris | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Tridontium | Scouleriales | Goffinet et al. (2009) | . | ICBN |
| Tridynamia | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Trieenea | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Trientalis | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Trifarina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Uvigerinidae. | ICZN |
| Trifascicularia | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Trifidacanthus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Trifolium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Triglochin | Alismatales | Mabberley (2008) | Juncaginaceae. | ICBN |
| Trigonachras | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Trigonaspis | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Papposphaeraceae. | ICBN |
| Trigonella | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Trigonepimerus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Trigonia | Malpighiales | Mabberley (2008) | Trigoniaceae. | ICBN |
| Trigoniastrum | Malpighiales | Mabberley (2008) | Trigoniaceae. | ICBN |
| Trigonidium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trigonobalanus | Fagales | Mabberley (2008) | Fagaceae. | ICBN |
| Trigonocapnos | Ranunculales | Mabberley (2008) | Papaveraceae. | ICBN |
| Trigonocaryum | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Trigonoceps | Falconiformes | Clements (2007) | . | ICZN |
| Trigonognathus | Squaliformes | Nelson (2006) | . | ICZN |
| Trigonomonas | Diplomonadida | Brugerolle & Lee (2000) | . | ICZN |
| Trigonopleura | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Trigonopterum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trigonopyxis | Arcellinida | Meisterfeld (2000) | Difflugina -- Trigonopyxidae. | ICZN |
| Trigonosciadium | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Trigonospermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trigonosporus | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Trigonostemon | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Trigonotis | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Trigynaea | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Trihymena | Bursariomorphida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Trikentrion | Poecilosclerida | Hooper (2002) | . | ICZN |
| Trikeraia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trilepidea | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Trilepis | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Trilepisium | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Trillium | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Trilobachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trilocularena | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Rzehakinidae. | ICZN |
| Triloculina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Triloculinella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Triloculinellus | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Triloculinoides | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Trilospora | Multivalvulida | Lom & Dyková (2006) | . | ICZN |
| Trilosporoides | Multivalvulida | Lom & Dyková (2006) | . | ICZN |
| Trimastigamoeba | Schizopyrenida | Patterson et al. (2000) | . | ICZN |
| Trimastix | Trimastigida | Cavalier-Smith (2003) | . | ICZN |
| Trimenia | Austrobaileyales | Mabberley (2008) | Trimeniaceae. | ICBN |
| Trimeresurus | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Trimeria | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Trimeris | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Trimetopon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Trimezia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Trimitus | Diplomonadida | Brugerolle & Lee (2000) | . | ICZN |
| Trimorphodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Trimosina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trimosinidae. | ICZN |
| Trimyema | Plagiopylida | Lynn (2008) | . | ICZN |
| Trinema | Euglyphida | Meisterfeld (2000) | . | ICZN |
| Tringa | Charadriiformes | Clements (2007) | . | ICZN |
| Trinia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Triniochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Triniteurybia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trinomys | Rodentia | Woods & Kilpatrick (2005) | . | ICZN |
| Trinovantedinium | Peridiniales | Fensome et al. (1993) | Holocene. | ICBN |
| Trinycteris | Chiroptera | Simmons (2005) | . | ICZN |
| Trioceros | Squamata | Tilbury & Tolley (2009) | Chamaeleonidae. | ICZN |
| Triodanis | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Triodia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Triodontoderes | Cyclorhagida | Sørensen & Rho (2009) | . | ICZN |
| Triolena | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Triomma | Sapindales | Mabberley (2008) | Burseraceae. | ICBN |
| Trioncinia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trionyx | Testudinata | Vitt & Caldwell (2009) | Trionychidae. | ICZN |
| Triopterys | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Triosteum | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Tripalea | Alcyonacea | Bayer (1981) | Anthothelidae. | ICZN |
| Tripalmaria | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Tripanurgos | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Triparma | Parmales | Booth & Marchant (1987) | . | ICBN |
| Tripartiella | Mobilida | Lynn (2008) | . | ICZN |
| Tripedalia | Cubomedusae | Kramp (1961) | . | ICZN |
| Triphasia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Triphora | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Triphyophyllum | Caryophyllales | Mabberley (2008) | Dioncophyllaceae. | ICBN |
| Triphysaria | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Triplachne | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tripladenia | Liliales | Mabberley (2008) | Colchicaceae. | ICBN |
| Triplagia | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Triplarina | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Triplaris | Caryophyllales | Mabberley (2008) | Polygonaceae. | ICBN |
| Triplasia | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Lituolidae. | ICZN |
| Triplasis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Triplastrum | Desmidiales | Gontcharov (2008) | . | ICBN |
| Triplecta | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Tripleuchlanis | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Tripleurospermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Triplignathia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Triplocephalum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Triploceras | Desmidiales | Gontcharov (2008) | . | ICBN |
| Triplochiton | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Triplophyllum | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Triplopogon | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Triplostegia | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Triplumaria | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Tripodanthus | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Tripodion | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tripogandra | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Tripogon | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tripolium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tripoma | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tripora | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Tripos | Gonyaulacales | Gómez et al. (2010); Calado & Huisman (2010); Gómez (2010) | Probably correct name for Neoceratium. | ICBN |
| Triposolenia | Dinophysiales | Fensome et al. (1993) | . | ICBN |
| Triprion | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Tripsacum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tripterocladium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Tripterococcus | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Tripterodendron | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tripterospermum | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Tripterygium | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Triptilodiscus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Triptolemma | Astrophorida | Maldonado (2002) | . | ICZN |
| Triquetrella | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Triraphis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Triscenia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trischidium | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Trisegmentina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Fischerinidae. | ICZN |
| Trisepalum | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Triseptata | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Trisetaria | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trisetella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trisetum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Trismegistia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trissopathes | Antipatharia | Opresko (2003) | . | ICZN |
| Tristachya | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tristagma | Asparagales | Mabberley (2008) | Alliaceae. | ICBN |
| Tristania | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Tristaniopsis | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Tristellateia | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Tristemma | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tristemonanthus | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Tristerix | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Tristicha | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Tristichium | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Tristira | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tristiropsis | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tritaxilina | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Valvulinidae. | ICZN |
| Tritaxis | Trochamminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trochamminidae. | ICZN |
| Triteleia | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Triteleiopsis | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Trithamnion | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Trithecanthera | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Trithigmostoma | Chlamydodontida | Lynn (2008) | . | ICZN |
| Trithrinax | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Trithuria | Nymphaeales | Mabberley (2008) | Hydatellaceae. | ICBN |
| Triticosecale | Poales | Mabberley (2008) | xTriticosecale. Triticum x Secale hybrids. Gramineae. | ICBN |
| Triticum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tritomaria | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Tritonia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Tritoniopsis | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Tritrichomonas | Tritrichomonadida | Cepicka et al. (2010) | . | ICZN |
| Triturus | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Triumfetta | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Triunia | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Triuridopsis | Pandanales | Mabberley (2008) | Triuridaceae. | ICBN |
| Triuris | Pandanales | Mabberley (2008) | Triuridaceae. | ICBN |
| Trivalvaria | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Trixis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trizeuxis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Trochammina | Trochamminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trochamminidae. | ICZN |
| Trochamminella | Trochamminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trochamminidae. | ICZN |
| Trochamminita | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Haplophragmoididae. | ICZN |
| Trochamminoides | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Lituotubidae. | ICZN |
| Trochamminopsis | Trochamminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trochamminidae. | ICZN |
| Trochamminula | Trochamminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Trochamminidae. | ICZN |
| Trochetia | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Trochetiopsis | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Trochilia | Dysteriida | Lynn (2008) | . | ICZN |
| Trochilioides | Dysteriida | Lynn (2008) | Nomen nudum. | ICZN |
| Trochiliopsis | Microthoracida | Lynn (2008) | . | ICZN |
| Trochilus | Apodiformes | Clements (2007) | . | ICZN |
| Trochiscanthes | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Trochobryum | Grimmiales | Goffinet et al. (2009) | . | ICBN |
| Trochocarpa | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Trochocercus | Passeriformes | Clements (2007) | . | ICZN |
| Trochochilodon | Dysteriida | Lynn (2008) | . | ICZN |
| Trochocyathus | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Trochodendron | Trochodendrales | Mabberley (2008) | Trochodendraceae. | ICBN |
| Trocholejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Trocholinopsis | Involutinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992); Sen Gupta (1999) | Planispirillinidae. | ICZN |
| Trochomeria | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Trochomeriopsis | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Trochopsammia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Trochosphaera | Flosculariaceae | Segers (2002); Segers (2007) | . | ICZN |
| Trochospongilla | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Trochulina | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Discorbidae. | ICZN |
| Troglocorys | Entodiniomorphida | Tokiwa et al. (2010) | . | ICZN |
| Troglodytella | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Troglodytes | Passeriformes | Clements (2007) | . | ICZN |
| Troglophyton | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Trogon | Trogoniformes | Clements (2007) | . | ICZN |
| Trogonophis | Squamata | Vitt & Caldwell (2009) | Trogonophidae. | ICZN |
| Trogopterus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Trolliella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Trollius | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Tromotriche | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tropaeolum | Brassicales | Mabberley (2008) | Tropaeolaceae. | ICBN |
| Tropheryma | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Trophis | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Trophogemma | Exogenida | Lynn (2008) | . | ICZN |
| Trophosphaera | Piroplasmorida | Perkins et al. (2000) | . | ICZN |
| Tropicibacter | Rhodobacterales | Harwati et al. (2009) | . | ICNB |
| Tropicimonas | Rhodobacterales | Harwati et al. (2009) | . | ICNB |
| Tropidechis | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Tropidia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tropidoatractus | Armophorida | Lynn (2008) | . | ICZN |
| Tropidocarpum | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Tropidoclonion | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tropidocyathus | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Tropidodipsas | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tropidodryas | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tropidolaemus | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Tropidonophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Tropidophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Tropidophiidae". | ICZN |
| Tropidophorus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Tropidosaura | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Tropidoscincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Tropidoscyphus | Sphenomonadales | Leedale (1967); Leedale (2000) | . | ICBN |
| Tropidurus | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Tropiocolotes | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Truebella | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Truepera | Deinococcales | Albuquerque et al. (2005) | . | ICNB |
| Trueperella | Actinomycetales | Yassin et al. (2011); Ludwig et al. (2012) | Actinomycetaceae. | ICNB |
| Trugon | Columbiformes | Clements (2007) | . | ICZN |
| Truncatoflabellum | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Truncatoguynia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Truncoheronallenia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Glabratellidae. | ICZN |
| Truncorotalia | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Globorotaliidae. | ICZN |
| Trunculocavus | Lituilida | Kaminski (2000) | Spiroplectamminacea. | ICZN |
| Trungboa | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Trygonoptera | Myliobatiformes | Nelson (2006) | . | ICZN |
| Trygonorrhina | Rajiformes | Nelson (2006) | . | ICZN |
| Trymalium | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Trymatococcus | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Tryngites | Charadriiformes | Clements (2007) | . | ICZN |
| Tryonella | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Trypanochloris | Mischococcales | Ettl (1978) | . | ICBN |
| Trypanococcus | Evaginogenida | Lynn (2008) | . | ICZN |
| Trypanodinium | Syndinida | Fensome et al. (1993) | . | ICZN |
| Trypanoplasma | Parabodonida | Moreira et al. (2004) | . | ICZN |
| Trypanosoma | Trypanosomatida | Moreira et al. (2004) | . | ICZN |
| Trypemonas | Euglenales | Marin et al. (2003) | Synonymous to Trachelomonas. | ICBN |
| Tryphomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tryponema | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Tryssophyton | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Tscherskia | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tsebona | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Tsengia | Cryptonemiales | Silva (2002); Schneider & Wynne (2007) | . | ICBN |
| Tsengiella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tsingya | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Tsitsikamma | Poecilosclerida | Samaai & Kelly (2002) | . | ICZN |
| Tsoala | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Tsoongia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Tsuga | Pinales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Tsukamurella | Corynebacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Tsukubamonas | Tsukubamonadida | Yabuki et al. (2011) | . | ICZN |
| Tubastraea | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Tuberaria | Malvales | Mabberley (2008) | Cistaceae. | ICBN |
| Tuberculocarpus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tuberibacillus | Bacillales | Hatayama et al. (2006) | . | ICNB |
| Tuberolabium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tuberostylis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tubiclava | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Tubiella | Synechococcales | Hoffmann et al. (2005) | . | ICBN |
| Tubifera | Liceales | Yamamoto (1998); Lado (2001); Lado (2011) | Correct name (Lado, 2011). | ICBN |
| Tubigorgia | Alcyonacea | Pasternak (1985) | Anthothelidae. | ICZN |
| Tubiluchus | Priapulomorpha | Adrianov & Malakhov (1996) | . | ICZN |
| Tubinella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Tubipora | Alcyonacea | Bayer (1981) | Tubiporidae. | ICZN |
| Tubonemertes | Pelagica | Gibson (1995) | . | ICZN |
| Tubulanus | Palaeonemertea | Gibson (1995) | . | ICZN |
| Tubularia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Tubulideres | Cyclorhagida | Sørensen et al. (2007) | . | ICZN |
| Tubulifera | Liceales | Yamamoto (1998); Lado (2001); Lado (2011) | Nomen nudum. | ICBN |
| Tubulinosema | Microsporida | Franzen et al. (2005) | . | ICZN |
| Tucolesca | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Tuctoria | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Tuerckheimia | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Tugarinovia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tulamoeba | Schizopyrenida | Park et al. (2009) | . | ICZN |
| Tulasneantha | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Tulbaghia | Asparagales | Mabberley (2008) | Alliaceae. | ICBN |
| Tulearinia | Lithonida | Vacelet et al. (2002) | . | ICZN |
| Tulipa | Liliales | Mabberley (2008) | Liliaceae. | ICBN |
| Tulpa | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Tumamoca | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Tumbezia | Passeriformes | Clements (2007) | . | ICZN |
| Tumebacillus | Bacillales | Steven et al. (2008) | . | ICNB |
| Tumidotubus | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Telamminidae. | ICZN |
| Tunicophrya | Exogenida | Lynn (2008) | . | ICZN |
| Tunicothrix | Urostylida | Lynn (2008) | . | ICZN |
| Tunilla | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Tuomeya | Batrachospermales | Schneider & Wynne (2007) | . | ICBN |
| Tupaia | Scandentia | McKenna & Bell (1997) | . | ICZN |
| Tupeia | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Tupinambis | Squamata | Vitt & Caldwell (2009) | Teiidae. | ICZN |
| Tupistra | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Turacoena | Columbiformes | Clements (2007) | . | ICZN |
| Turaniella | Tetrahymenida | Lynn (2008) | . | ICZN |
| Turbanella | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Turbina | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Turbinaria | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Turbinolia | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Turborotalita | Globigerinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Globigerinidae. | ICZN |
| Turczaninowiella | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Turdoides | Passeriformes | Clements (2007) | . | ICZN |
| Turdus | Passeriformes | Clements (2007) | . | ICZN |
| Turgenia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Turicella | Corynebacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Turicibacter | Erysipelotrichales | Garrity et al. (2005); Ludwig et al. (2009) | . | ICNB |
| Turkmenella | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Turnera | Malpighiales | Mabberley (2008) | Passifloraceae. | ICBN |
| Turnerella | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Turneriella | Spirochaetales | Levett et al. (2005) | . | ICNB |
| Turnix | Gruiformes | Clements (2007) | . | ICZN |
| Turpinia | Crossosomatales | Mabberley (2008) | Staphyleaceae. | ICBN |
| Turraea | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Turraeanthus | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Turricula | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Turrilithus | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Syracosphaerales ?. | ICBN |
| Turrispirillina | Spirillinida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spirillinidae. | ICZN |
| Turritellella | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ammodiscidae. | ICZN |
| Turritis | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Turritopsis | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Turritopsoides | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Tursiops | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Turtur | Columbiformes | Clements (2007) | . | ICZN |
| Tuscaretta | Phaeocalpida | Takahashi & Anderson (2000) | . | ICZN |
| Tuscarilla | Phaeocalpida | Takahashi & Anderson (2000) | . | ICZN |
| Tuscarora | Phaeocalpida | Takahashi & Anderson (2000) | . | ICZN |
| Tussilago | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tuxtla | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tuyamaella | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Tuzetia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Tuzibeanthus | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Tweedia | Gentianales | Rapini et al. (2011) | Apocynaceae. | ICBN |
| Tychonema | Oscillatoriales | Hoffmann et al. (2005) | . | ICBN |
| Tychosporium | Protosteliales | Spiegel et al. (1995) | . | ICBN |
| Tylas | Passeriformes | Clements (2007) | . | ICZN |
| Tylecodon | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Tyleria | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Tyleropappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tylexocladus | Hadromerida | Boury-Esnault (2002) | . | ICZN |
| Tylimanthus | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Tylobranchion | Aplousobranchia | Monniot & Monniot (1972); Kott (1998); Monniot (2001) | Diazonidae. | ICZN |
| Tylocolax | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Tylomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tylonycteris | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Tylopathes | Antipatharia | Opresko (2006) | . | ICZN |
| Tylophora | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Tylopsacas | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Tylosema | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Tylostigma | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Tylototriton | Caudata | Vitt & Caldwell (2009) | Salamandridae. | ICZN |
| Tylotrocha | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Tylotus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Tympanocryptis | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Tympanoctomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Tympanuchus | Galliformes | Clements (2007) | . | ICZN |
| Tynanthus | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Typha | Poales | Mabberley (2008) | Typhaceae. | ICBN |
| Typhlacontias | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Typhloerstedia | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Oerstediidae. | ICZN |
| Typhlomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Typhlonarke | Torpediniformes | Nelson (2006) | . | ICZN |
| Typhlonectes | Gymnophiona | Vitt & Caldwell (2009) | Typhlonectidae. | ICZN |
| Typhloperipatus | Euonychophora | Peck (1975) | Peripatidae. | ICZN |
| Typhlophis | Squamata | Vitt & Caldwell (2009) | Serpentes. Anomalepididae. | ICZN |
| Typhlops | Squamata | Vitt & Caldwell (2009) | Serpentes. Typhlopidae. | ICZN |
| Typhlosaurus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Typhonium | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Typhonodorum | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Tyranneutes | Passeriformes | Clements (2007) | . | ICZN |
| Tyrannodinium | Peridiniales | Calado et al. (2009) | Pfiesteriaceae. | ICBN |
| Tyrannopsis | Passeriformes | Clements (2007) | . | ICZN |
| Tyrannulus | Passeriformes | Clements (2007) | . | ICZN |
| Tyrannus | Passeriformes | Clements (2007) | . | ICZN |
| Tyrbastes | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Tyrimnus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Tyto | Strigiformes | Clements (2007) | . | ICZN |
| Tyzzeria | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| U | |
| Uapaca | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Uchidana | Heteronemertea | Gibson (1995) | . | ICZN |
| Uebelinia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Uebelmannia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Uechtritzia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ugamia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ugni | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Uittienia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Uladendron | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Uleanthus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Ulearum | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Uleastrum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Uleiorchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Uleobryum | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Uleophytum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ulex | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Uliginosibacterium | Rhodocyclales | Weon et al. (2008) | . | ICNB |
| Ulivina | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Ulkenia | Thraustochytriales | Dick (2001); Kirk et al. (2008) | Thraustochytriaceae. | ICBN |
| Ullucus | Caryophyllales | Mabberley (2008) | Basellaceae. | ICBN |
| Ulmaris | Semaeostomeae | Kramp (1961) | . | ICZN |
| Ulmus | Rosales | Mabberley (2008) | Ulmaceae. | ICBN |
| Ulosa | Poecilosclerida | Van Soest & Hajdu (2002) | . | ICZN |
| Ulota | Orthotrichales | Goffinet et al. (2009) | . | ICBN |
| Ululania | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Ulvibacter | Flavobacteriales | Nedashkovskaya et al. (2004) | . | ICNB |
| Uma | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Umbellapathes | Antipatharia | Opresko (2005) | . | ICZN |
| Umbellosphaera | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Umbellosphaeraceae. | ICBN |
| Umbellularia | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Umbellulifera | Alcyonacea | Bayer (1981) | Nephtheidae. | ICZN |
| Umbilicosphaera | Coccolithales | Jordan et al. (2004) | Calcidiscaceae. | ICBN |
| Umbilicus | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Umboniibacter | | Romanenko et al. (2010) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria. | ICNB |
| Umborotula | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Umbracephalus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Umbrivaga | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Umezakia | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Umezawaea | Pseudonocardiales | Labeda & Kroppensetedt (2007); Ludwig et al. (2012) | . | ICNB |
| Umtiza | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Unantra | Acoela | Faubel & Noreña (2001) | . | ICZN |
| Uncaria | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Uncarina | Lamiales | Mabberley (2008) | Pedaliaceae. | ICBN |
| Uncia | Carnivora | Wozencraft (2005) | . | ICZN |
| Uncifera | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Uncinata | | Lynn (2008) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Ciliophora - Class Spirotrichea - Subclass Stichotrichia. | ICZN |
| Uncinatera | Aulocalycoida | Reiswig (2002) | . | ICZN |
| Uncinia | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Unclejackia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Unda | Vannellida | Rogerson & Patterson (2000); Smirnov et al. (2005) | Vannellidae. | ICZN |
| Undella | Tintinnida | Lynn (2008) | . | ICZN |
| Undellopsis | Tintinnida | Lynn (2008) | . | ICZN |
| Underwoodisaurus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Undibacterium | Burkholderiales | Kämpfer et al. (2007) | . | ICNB |
| Undosa | Semaeostomeae | Kramp (1961) | . | ICZN |
| Undula | Chaetonotida | Balsamo et al. (2009) | . | ICZN |
| Ungaliophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Tropidophiidae". | ICZN |
| Ungeria | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Ungernia | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Ungnadia | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Ungulatella | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ungulatellidae. | ICZN |
| Ungulatelloides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ungulatellidae. | ICZN |
| Ungulipetalum | Ranunculales | Mabberley (2008) | Menispermaceae. | ICBN |
| Unicapsula | Multivalvulida | Lom & Dyková (2006) | . | ICZN |
| Unicauda | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Unikaryon | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Uniola | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Uniporus | Reptantia | Gibson (1995) | . | ICZN |
| Uniscyphus | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Unonopsis | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Unxia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Uperodon | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Uperoleia | Anura | Vitt & Caldwell (2009) | Myobatrachidae. | ICZN |
| Upucerthia | Passeriformes | Clements (2007) | . | ICZN |
| Upuna | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Upupa | Coraciiformes | Clements (2007) | . | ICZN |
| Uracentron | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Uradiophora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Uraeginthus | Passeriformes | Clements (2007) | . | ICZN |
| Uraeotyphlus | Gymnophiona | Vitt & Caldwell (2009) | Uraeotyphlidae. | ICZN |
| Uragus | Passeriformes | Clements (2007) | . | ICZN |
| Uranomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Uranoscodon | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Uranthoecium | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Uraria | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Urashimea | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Uratelornis | Coraciiformes | Clements (2007) | . | ICZN |
| Urbananthus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Urbania | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Urbanodendron | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Urbinella | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Urceodiscus | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Urceola | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Urceolaria | Mobilida | Lynn (2008) | Later synonym of Trichodinopsis??. | ICZN |
| Urceolina | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Urceolus | Heteronematales | Leedale (1967); Leedale (2000) | . | ICBN |
| Ureaplasma | Mycoplasmatales | Garrity et al. (2005) | . | ICNB |
| Ureibacillus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Urelytrum | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Urena | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Urera | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Urgorri | Pyrenomonadales | Laza-Martínez (2012) | . | ICBN |
| Uria | Charadriiformes | Clements (2007) | . | ICZN |
| Uribea | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Uricholemma | Heteronemertea | Kajihara et al. (2008) | . | ICZN |
| Urichonemertes | Reptantia | Gibson (1995); Kajihara et al. (2008) | Junior synonym of Punnettia. | ICZN |
| Urinympha | Trichonymphida | Cepicka et al. (2010) | . | ICZN |
| Urliella | Nassulida | Lynn (2008) | . | ICZN |
| Urmenetea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Urnaepimeritus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Urnaloricus | Nanaloricida | Heiner & Kristensen (2009) | . | ICZN |
| Urnatella | Coloniales | Emschermann (1972) | Barentsiidae. | ICZN |
| Urnula | Exogenida | Lynn (2008) | . | ICZN |
| Urobatis | Myliobatiformes | Nelson (2006) | . | ICZN |
| Urobotrya | Santalales | Mabberley (2008) | Opiliaceae. | ICBN |
| Urocentrum | Urocentrida | Lynn (2008) | . | ICZN |
| Urochaenia | Haptorida | Lynn (2008) | . | ICZN |
| Urochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Urochondra | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Urochroa | Apodiformes | Clements (2007) | . | ICZN |
| Urocissa | Passeriformes | Clements (2007) | . | ICZN |
| Urocolius | Coliiformes | Clements (2007) | . | ICZN |
| Urocotyledon | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Urocyclon | Philasterida | Lynn (2008) | . | ICZN |
| Urocynchramus | Passeriformes | Clements (2007) | . | ICZN |
| Urocyon | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Urodasys | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Uroderma | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Urodon | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Urogale | Scandentia | McKenna & Bell (1997) | . | ICZN |
| Urogentias | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Uroglaux | Strigiformes | Clements (2007) | . | ICZN |
| Uroglena | Ochromonadales | Kristiansen & Preisig (2001); Wujek & Thompson (2002); Cavalier-Smith & Chao (2006) | Chromulinaceae (biflagellate). | ICBN |
| Uroglenopsis | Ochromonadales | Wujek & Thompson (2002) | . | ICBN |
| Urogymnus | Myliobatiformes | Nelson (2006) | . | ICZN |
| Urolais | Passeriformes | Clements (2007) | . | ICZN |
| Urolepis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Uroleptoides | Stichotrichida | Lynn (2008) | . | ICZN |
| Uroleptopsis | Urostylida | Lynn (2008) | . | ICZN |
| Uroleptus | Urostylida | Lynn (2008) | . | ICZN |
| Urolophus | Myliobatiformes | Nelson (2006) | . | ICZN |
| Uromacer | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Uromacerina | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Uromanis | Pholidota | McKenna & Bell (1997); Schlitter (2005) | Later synonym of Manis. | ICZN |
| Uromastyx | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Uromyrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Uromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Uronema | Philasterida | Lynn (2008) | . | ICZN |
| Uronemella | Philasterida | Lynn (2008) | . | ICZN |
| Uronemopsis | Philasterida | Lynn (2008) | . | ICZN |
| Uronychia | Euplotida | Lynn (2008) | . | ICZN |
| Uropappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Uropedalium | Philasterida | Lynn (2008) | . | ICZN |
| Uropelia | Columbiformes | Clements (2007) | . | ICZN |
| Uropeltis | Squamata | Vitt & Caldwell (2009) | Serpentes. Uropeltidae. | ICZN |
| Urophyllum | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Urophysa | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Uroplatus | Squamata | Vitt & Caldwell (2009) | Gekkonidae. | ICZN |
| Uropogon | Vestibuliferida | Lynn (2008) | . | ICZN |
| Uropsalis | Caprimulgiformes | Clements (2007) | . | ICZN |
| Uropsila | Passeriformes | Clements (2007) | . | ICZN |
| Uropsilus | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Urorhipis | Passeriformes | Clements (2007) | . | ICZN |
| Urosaurus | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Uroskinnera | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Urosoma | Sporadotrichida | Lynn (2008) | . | ICZN |
| Urosomoida | Sporadotrichida | Lynn (2008) | . | ICZN |
| Urospatha | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Urospermum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Urosphena | Passeriformes | Clements (2007) | . | ICZN |
| Urospinula | Stichotrichida | Lynn (2008) | Later synonym of Psilotricha?. | ICZN |
| Urospora | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Urosporidium | Haplosporida | Bass et al. (2009) | . | ICZN |
| Urostephanus | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Urosticte | Apodiformes | Clements (2007) | . | ICZN |
| Urostrongylum | Stichotrichida | Lynn (2008) | . | ICZN |
| Urostrophus | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Urostyla | Urostylida | Lynn (2008) | . | ICZN |
| Urotheca | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Urothraupis | Passeriformes | Clements (2007) | . | ICZN |
| Urotricha | Prorodontida | Lynn (2008) | . | ICZN |
| Urotrichus | Eulipotyphla | McKenna & Bell (1997); Murphy et al. (2001) | . | ICZN |
| Urotriorchis | Falconiformes | Clements (2007) | . | ICZN |
| Urotrygon | Myliobatiformes | Nelson (2006) | . | ICZN |
| Urozona | Philasterida | Lynn (2008) | . | ICZN |
| Ursinia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ursus | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Urtica | Rosales | Mabberley (2008) | Urticaceae. | ICBN |
| Urticina | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Urticinopsis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Uruburuella | Neisseriales | Vela et al. (2005) | . | ICNB |
| Uruguaya | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Uruguayella | Haplosclerida | Manconi & Pronzato (2002) | . | ICZN |
| Urvillea | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Usbekistania | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ammodiscidae. | ICZN |
| Usconophrys | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Usteria | Gentianales | Mabberley (2008) | Loganiaceae. | ICBN |
| Uta | Squamata | Vitt & Caldwell (2009) | Iguanidae. | ICZN |
| Ute | Leucosolenida | Borojevic et al. (2002) | . | ICZN |
| Uteopsis | Leucosolenida | Borojevic et al. (2002) | . | ICZN |
| Uteronympha | Spirotrichonymphida | Cepicka et al. (2010) | . | ICZN |
| Utleya | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Utolineides | Heteronemertea | Kajihara et al. (2008) | . | ICZN |
| Utolineus | Heteronemertea | Gibson (1995) | . | ICZN |
| Utricularia | Lamiales | Mabberley (2008) | Lentibulariaceae. | ICBN |
| Utsetela | Rosales | Mabberley (2008) | Moraceae. | ICBN |
| Uvaria | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Uvariastrum | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Uvariodendron | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Uvariopsis | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Uvelinus | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Uvigerina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Uvigerinidae. | ICZN |
| Uvularia | Liliales | Mabberley (2008) | Colchicaceae. | ICBN |
| V | |
| Vaccaria | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Vaccinium | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Vaceletia | Verticillitida | Vacelet (2002) | . | ICZN |
| Vachellia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vacuolaria | Raphidomonadales | Heywood & Leedale (2000) | . | ICBN |
| Vadicella | Rhodobacterales | Romanenko et al. (2011) | . | ICNB |
| Vagaria | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Vaginicola | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Vaginulina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Vaginulinopsis | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Vaginulinidae. | ICZN |
| Vagococcus | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Vahadenia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vahlia | Vahliales | Mabberley (2008) | Vahliaceae. | ICBN |
| Vahlkampfia | Schizopyrenida | Patterson et al. (2000) | . | ICZN |
| Vahlodea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vailia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vairimorpha | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Valantia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Valdivianemertes | Cratenemertea | Gibson (1995); Crandall & Gibson (1998); Kajihara et al. (2008) | Rejected name. Synonymous to Akrostomum. | ICZN |
| Valencinia | Heteronemertea | Gibson (1995) | . | ICZN |
| Valencinina | Heteronemertea | Gibson (1995) | . | ICZN |
| Valencinura | Heteronemertea | Gibson (1995) | . | ICZN |
| Valeriana | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Valerianella | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Valeriemaya | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Valkomonas | | Yabuki et al. (2012) | Domain Eucarya - Superkingdom Bikonta (possibly "Chromista"). | ICZN |
| Vallariopsis | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vallaris | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vallea | Oxalidales | Mabberley (2008) | Elaeocarpaceae. | ICBN |
| Vallentinia | Limnomedusae | Bouillon et al. (2006) | . | ICZN |
| Vallesia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Valletofolliculina | Heterotrichida | Lynn (2008) | . | ICZN |
| Vallicula | Platyctenida | Harbison & Madin (1982) | . | ICZN |
| Vallisneria | Alismatales | Mabberley (2008) | Hydrocharitaceae. | ICBN |
| Valvobifarina | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Reussellidae. | ICZN |
| Valvognathia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Valvulina | Textulariida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Valvulinidae. | ICZN |
| Valvulineria | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Bagginidae. | ICZN |
| Vampirovibrio | Bdellovibrionales | Garrity et al. (2005) | . | ICNB |
| Vampyrella | Aconchulinida | Bass et al. (2009) | . | ICZN |
| Vampyrellidium | Nucleariida | Patterson et al. (2000) | . | ICZN |
| Vampyrelloides | Aconchulinida | Bass et al. (2009) | . | ICZN |
| Vampyressa | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Vampyrocrossota | Trachymedusae | Bouillon et al. (2006) | . | ICZN |
| Vampyrodes | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Vampyrognathia | Bursovaginoidea | Sørensen (2002) | . | ICZN |
| Vampyrophrya | Apostomatida | Lynn (2008) | . | ICZN |
| Vampyrum | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Vanaea | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Vanasushava | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Vancouveria | Ranunculales | Mabberley (2008) | Berberidaceae. | ICBN |
| Vanda | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Vandasina | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vandeleuria | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Vandenboschia | Hymenophyllales | Christenhusz et al. (2011) | . | ICBN |
| Vandiemenia | Metzgeriales | Crandall-Stotler et al. (2009) | . | ICBN |
| Vandijkophrynus | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Vandopsis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Vanellus | Charadriiformes | Clements (2007) | . | ICZN |
| Vanga | Passeriformes | Clements (2007) | . | ICZN |
| Vangueria | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Vangueriella | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Vangueriopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Vanheerdea | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Vanhoeffenella | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Astrorhizidae. | ICZN |
| Vanhovenia | Exogenida | Lynn (2008) | . | ICZN |
| Vanilla | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Vannella | Vannellida | Rogerson & Patterson (2000); Smirnov et al. (2005) | . | ICZN |
| Vannuccia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Vanoverberghia | Zingiberales | Mabberley (2008) | Zingiberaceae. | ICBN |
| Vanroyenella | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Vantanea | Malpighiales | Mabberley (2008) | Humiriaceae. | ICBN |
| Vanvoorstia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Vanwykia | Santalales | Mabberley (2008) | Loranthaceae. | ICBN |
| Vanzijlia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Vanzosaura | Squamata | Vitt & Caldwell (2009) | Gymnophthalmidae. | ICZN |
| Varanus | Squamata | Vitt & Caldwell (2009) | Varanidae. | ICZN |
| Varecia | Primates | McKenna & Bell (1997) | . | ICZN |
| Vargasiella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Varibaculum | Actinomycetales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Varidentella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Variemenia | Gigartinales | Wynne & Schneider (2010) | . | ICBN |
| Varilla | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Variovorax | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Varitentaculata | Trachymedusae | Bouillon et al. (2006) | . | ICZN |
| Varthemia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vasacineta | Endogenida | Lynn (2008) | . | ICZN |
| Vasconcellea | Brassicales | Mabberley (2008) | Caricaceae. | ICBN |
| Vaseyanthus | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Vaseyochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vasichona | Exogemmida | Lynn (2008) | . | ICZN |
| Vasicola | Prostomatida | Lynn (2008) | . | ICZN |
| Vasicostella | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ellipsolagenidae. | ICZN |
| Vasilyevaea | Rhizobiales | Yee et al. (2010) | . | ICNB |
| Vasivaea | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Vasqueziella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Vassilczenkoa | Caryophyllales | Mabberley (2008) | Plumbaginaceae. | ICBN |
| Vassobia | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Vatairea | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vataireopsis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vateria | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Vateriopsis | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Vatica | Malvales | Mabberley (2008) | Dipterocarpaceae. | ICBN |
| Vatovaea | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vaucheria | Vaucheriales | Rieth (1980) | . | ICBN |
| Vauchomia | Mobilida | Lynn (2008) | . | ICZN |
| Vaughanella | Scleractinia | Cairns et al. (1999) | . | ICZN |
| Vaughania | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vaupesia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Vauquelinia | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Vavaea | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Vavara | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Vavilovia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vavraia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Vazella | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Vegaeae | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Veillonella | Selenomonadales | Garrity et al. (2005); Marchandin et al. (2010) | . | ICNB |
| Veillonia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Veitchia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Velamen | Cestida | Harbison & Madin (1982) | . | ICZN |
| Velascoa | Crossosomatales | Mabberley (2008) | Crossosomataceae. | ICBN |
| Velatocarpus | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Velella | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Veleroa | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Veleroninoides | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Haplophragmoididae. | ICZN |
| Velezia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Velistoma | Philasterida | Lynn (2008) | . | ICZN |
| Velkovrhia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Vella | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Vellaria | Allogromiida | Kaminski (2000) | Allogromiinae. | ICZN |
| Velleia | Asterales | Mabberley (2008) | Goodeniaceae. | ICBN |
| Vellereophyton | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vellosiella | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Vellozia | Pandanales | Mabberley (2008) | Velloziaceae. | ICBN |
| Veltheimia | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Venegasia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Venenivibrio | Aquificales | Hetzer et al. (2008) | . | ICNB |
| Veniliornis | Piciformes | Clements (2007) | . | ICZN |
| Ventenata | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Ventilago | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Ventricularia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Ventrifissura | Ventricleftida | Howe et al. (2011) | . | ICZN |
| Ventromma | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Ventrostoma | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ellipsolagenidae. | ICZN |
| Venturiella | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Vepris | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Veracineta | Endogenida | Lynn (2008) | . | ICZN |
| Veratrilla | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Veratrum | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Verbascum | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Verbena | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Verbenoxylon | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Verbesina | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Verdigellas | Palmophyllales | Zechman et al. (2010) | . | ICBN |
| Verdoornia | Metzgeriales | Crandall-Stotler et al. (2009) | . | ICBN |
| Verdoornianthus | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Veretillum | Pennatulacea | Williams (1995) | . | ICZN |
| Vermamoeba | Echinamoebida | Smirnov et al. (2011) | . | ICZN |
| Vermicella | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Verminephrobacter | Burkholderiales | Pinel et al. (2008) | Validly published by Validation List no. 148. | ICNB |
| Vermioxytricha | Sporadotrichida | Lynn (2008) | . | ICZN |
| Vermistella | Stygamoebida | Moran et al. (2007); Smirnov et al. (2011) | . | ICZN |
| Vermivora | Passeriformes | Clements (2007) | . | ICZN |
| Vernaya | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Verneuilinulla | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Globotextulariidae. | ICZN |
| Vernicia | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Vernonanthura | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vernonia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vernoniopsis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Verongula | Verongida | Bergquist & Cook (2002) | . | ICZN |
| Veronica | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Veronicastrum | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Verreauxia | Asterales | Mabberley (2008) | Goodeniaceae. | ICBN |
| Verrillactis | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Verrillianemertes | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Tetrastemmatidae. | ICZN |
| Verrucalvus | Saprolegniales | Dick (2001); Kirk et al. (2008) | Saprolegniaceae. | ICBN |
| Verrucella | Alcyonacea | Bayer (1981); Bayer & Grasshoff (1994) | Junior synonym of Nicella. | ICZN |
| Verrucidens | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Verrucina | Astrorhizida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hemisphaeramminidae. | ICZN |
| Verrucocoeloidea | Hexactinosida | Reiswig & Wheeler (2002) | . | ICZN |
| Verrucomicrobium | Verrucomicrobiales | Garrity et al. (2005) | . | ICNB |
| Verrucomonas | Ventricleftida | Howe et al. (2011) | . | ICZN |
| Verrucophora | Florenciellales | Edvardsen et al. (2007); Eikrem et al. (2009) | Later synonym of Pseudochattonella. | ICBN |
| Verrucosispora | Micromonosporales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Verrucularia | Malpighiales | Mabberley (2008) | Malpighiaceae. | ICBN |
| Verschaffeltia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Versluysia | Alcyonacea | Bayer (1981) | Acanthogorgiidae. | ICZN |
| Versteegia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Versuriga | Rhizostomeae | Kramp (1961) | . | ICZN |
| Vertebralina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Fischerinidae. | ICZN |
| Vertebrasigmoilina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Vertebrata | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Verticordia | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Vescerro | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Veselskya | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Vesicularia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Vesiculariopsis | Hookeriales | Goffinet et al. (2009) | . | ICBN |
| Vesonyctus | Clevelandellida | Lynn (2008) | . | ICZN |
| Vespadelus | Chiroptera | Simmons (2005) | . | ICZN |
| Vespertilio | Chiroptera | McKenna & Bell (1997) | . | ICZN |
| Vesselowskya | Oxalidales | Mabberley (2008) | Cunoniaceae. | ICBN |
| Vestia | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Vestiaria | Passeriformes | Clements (2007) | . | ICZN |
| Vestibulongum | Vestibuliferida | Lynn (2008) | . | ICZN |
| Vetaforma | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Vetulina | | Pisera & Lévi (2002) | Domain Eucarya - Kingdom Animalia - Phylum Porifera - Class Demospongiae (lithistids) Vetulinidae. | ICZN |
| Vexillarius | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007); Andruleit & Young (2010) | Papposphaeraceae. | ICBN |
| Vexillifera | Dactylopodida | Rogerson & Patterson (2000); Smirnov et al. (2005) | . | ICZN |
| Veyretella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Vibrio | Vibrionales | Garrity et al. (2005) | . | ICNB |
| Viburnum | Dipsacales | Mabberley (2008) | Adoxaceae. | ICBN |
| Vicatia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Vicia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vickersia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Victivallis | Victivallales | Cho et al. (2004) | . | ICNB |
| Victorgorgia | Alcyonacea | López-González & Briand (2002) | Anthothelidae. | ICZN |
| Victoria | Nymphaeales | Mabberley (2008) | Nymphaeaceae. | ICBN |
| Vicugna | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Artiodactyla. | ICZN |
| Vidalasia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Vidalia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Vidua | Passeriformes | Clements (2007) | . | ICZN |
| Viennotia | Peronosporales | Kirk et al. (2008) | Peronosporaceae. | ICBN |
| Vieraea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Viereckia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vietnamia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vietnamocalamus | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vietnamochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vietnascincus | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Vietsenia | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Vigethia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vigna | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Viguiera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Viguieranthus | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Viguierella | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vijayachelys | Testudinata | Vitt & Caldwell (2009) | Geomydidae. | ICZN |
| Villadia | Saxifragales | Mabberley (2008) | Crassulaceae. | ICBN |
| Villanova | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Villaria | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Villarsia | Asterales | Mabberley (2008) | Menyanthaceae. | ICBN |
| Villasenoria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Villogorgia | Alcyonacea | Bayer (1981) | Plexauridae. | ICZN |
| Viminaria | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vinca | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vincetoxicopsis | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vincetoxicum | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Vindasia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Vini | Psittaciformes | Clements (2007) | . | ICZN |
| Vinkia | Saxifragales | Mabberley (2008) | Haloragaceae. | ICBN |
| Vinkiella | Gnetales | Won & Renner (2003); Mabberley (2008) | Later synonym of Gnetum. Nomen nudum. | ICBN |
| Viola | Malpighiales | Mabberley (2008) | Violaceae. | ICBN |
| Vipera | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Virectaria | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Vireo | Passeriformes | Clements (2007) | . | ICZN |
| Vireolanius | Passeriformes | Clements (2007) | . | ICZN |
| Virgibacillus | Bacillales | Garrity et al. (2005) | . | ICNB |
| Virgilia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Virginia | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Virgisporangium | Micromonosporales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Virgularia | Pennatulacea | Williams (1995) | . | ICZN |
| Virgulinella | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Virgulinellidae. | ICZN |
| Virgulinopsis | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Stainforthiidae. | ICZN |
| Virgulopsis | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Stainforthiidae. | ICZN |
| Virgulopsoides | Buliminida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Stainforthiidae. | ICZN |
| Viridantha | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Viridibacillus | Bacillales | Albert et al. (2007) | . | ICNB |
| Viridiella | | Neustupa et al. (2009); Darienko et al. (2010) | Domain Eucarya - Phylum Chlorophyta - Class Trebouxiophyceae. Watanabea-clade. | ICBN |
| Viridivellus | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Viridivia | Malpighiales | Mabberley (2008) | Passifloraceae. | ICBN |
| Viridovipera | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Virola | Magnoliales | Mabberley (2008) | Myristicaceae. | ICBN |
| Virotia | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Viscainoa | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Vischeria | Eustigmatales | Hibberd (1981): Hegewald et al. (2007) | . | ICBN |
| Viscum | Santalales | Mabberley (2008) | Santalaceae. | ICBN |
| Vismia | Malpighiales | Mabberley (2008) | Hypericaceae. | ICBN |
| Vismianthus | Oxalidales | Mabberley (2008) | Connaraceae. | ICBN |
| Visnea | Ericales | Mabberley (2008) | Pentaphylacaceae. | ICBN |
| Vitalianthus | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Vitellaria | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Vitellariopsis | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Vitellibacter | Flavobacteriales | Nedashkovskaya et al. (2003) | . | ICNB |
| Vitex | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Viticipremna | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Vitis | Vitales | Mabberley (2008) | Vitaceae. | ICBN |
| Vitrella | | Oborník et al. (2012) | Domain Eucarya - Kingdom Alveolatobiontes - Phylum Chromerida. | ICZN |
| Vitreosagitta | Aphragmophora | Kasatkina (2010) | Sagittidae. Now checking. | ICZN |
| Vitreoscilla | Neisseriales | Garrity et al. (2005) | . | ICNB |
| Vitrollula | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Vittadinia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vittaforma | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Vittaria | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Vittetia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Vittia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Vityaziella | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Viverra | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Viverricula | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Viviania | Geraniales | Mabberley (2008) | Vivianiaceae. | ICBN |
| Viviera | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Vlokia | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Voacanga | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Voalavo | Rodentia | Musser & Carleton (2005) | . | ICZN |
| Voanioala | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Voatamalo | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Vochysia | Myrtales | Mabberley (2008) | Vochysiaceae. | ICBN |
| Voeltzkowia | Squamata | Vitt & Caldwell (2009) | Scincidae. | ICZN |
| Vogesella | Neisseriales | Garrity et al. (2005) | . | ICNB |
| Vogtia | Siphonophorae | Bouillon et al. (2006) | . | ICZN |
| Voitia | Splachnales | Goffinet et al. (2009) | . | ICBN |
| Volatinia | Passeriformes | Clements (2007) | . | ICZN |
| Volemys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Volkanus | Acanthoecida | Leadbeater & Thomsen (2000); Doweld (2003); Özdikmen (2009) | Junior synonym of Didymoeca. | ICZN |
| Volkensinia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Volkiella | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Volucribacter | Pasteurellales | Christensen et al. (2004) | . | ICNB |
| Volutaria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Volutella | Tectofilosida | Meisterfeld (2000); Cavalier-Smith & Chao (2003) | Volutellidae. | ICZN |
| Volzia | Hadromerida | Rützler (2002) | . | ICZN |
| Vombatus | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Vonkleinsmidia | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Eponididae. | ICZN |
| Vonkleinsmidoides | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Eponididae. | ICZN |
| Voragonema | Trachymedusae | Bouillon et al. (2006) | . | ICZN |
| Vormela | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Voromonas | Voromonadida | Cavalier-Smith & Chao (2004) | . | ICZN |
| Vorticella | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Vorticellides | Peritrichida | Foissner et al. (2009) | . | ICZN |
| Vosmaeria | Halichondrida | Erpenbeck & Van Soest (2002) | . | ICZN |
| Vosmaeropsis | Leucosolenida | Borojevic et al. (2002) | . | ICZN |
| Vossia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vostonica | Exogenida | Lynn (2008) | . | ICZN |
| Votadinium | Peridiniales | Fensome et al. (1993) | Holocene. | ICBN |
| Votomita | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Votschia | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Vouacapoua | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Vouarana | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Voukiella | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Voyria | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Voyriella | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Vriesea | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Vrihiamoeba | Schizopyrenida | Murase et al. (2010) | . | ICZN |
| Vrolijkheidia | Pottiales | Hedderson & Zander (2008) | . | ICBN |
| Vrydagzynea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Vulcanella | Astrophorida | Maldonado (2002) | . | ICZN |
| Vulcanibacillus | Bacillales | L'Haridon et al. (2006) | . | ICNB |
| Vulcanisaeta | Thermoproteales | Garrity et al. (2005) | . | ICNB |
| Vulcanithermus | Thermales | Garrity et al. (2005) | . | ICNB |
| Vulcanodinium | Peridiniales | Nezan & Chomerat (2011) | . | ICBN |
| Vulcanonemertes | Eumonostilifera | Chernyshev (2005); Kajihara et al. (2008) | Neesidae. | ICZN |
| Vulpes | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Vulpia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vulpiella | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Vultur | Falconiformes | Clements (2007) | . | ICZN |
| Vulvulina | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Spiroplectamminidae. | ICZN |
| Vvedenskyella | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| W | |
| Wachendorfia | Commelinales | Mabberley (2008) | Haemodoraceae. | ICBN |
| Waddlia | Chlamydiales | Garrity et al. (2005) | . | ICNB |
| Waernia | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Waglerophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Wagnerella | Gymnosphaerida | Mikrjukov et al. (2000); Adl et al. (2005) | Other Heliozoa. | ICZN |
| Wagneriopteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Wahlenbergia | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Wailesella | Arcellinida | Meisterfeld (2000) | Phryganellina -- Cryptodifflugiidae. | ICZN |
| Wailesia | Tintinnida | Lynn (2008) | . | ICZN |
| Waireia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Waitzia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Wajira | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Wakea | Anura | Vitt & Caldwell (2009) | Mantellidae. | ICZN |
| Waldoia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Waldoschmittia | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Polymorphinidae. | ICZN |
| Waldsteinia | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Wallabia | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| Wallacea | Malpighiales | Mabberley (2008) | Ochnaceae. | ICBN |
| Wallaceina | Trypanosomatida | Moreira et al. (2004) | . | ICZN |
| Wallaceodendron | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Wallackia | Stichotrichida | Lynn (2008) | . | ICZN |
| Wallenia | Ericales | Mabberley (2008) | Primulaceae. | ICBN |
| Walleria | Asparagales | Mabberley (2008) | Tecophilaeaceae. | ICBN |
| Wallichia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Walsura | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Walteranthus | Brassicales | Mabberley (2008) | Gyrostemonaceae. | ICBN |
| Walteria | Lyssacinosida | Tabachnick (2002) | . | ICZN |
| Walterinnesia | Squamata | Vitt & Caldwell (2009) | Serpentes. Elapidae. | ICZN |
| Walterparria | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ellipsolagenidae. | ICZN |
| Waltherarndtia | Poecilosclerida | Hooper (2002) | . | ICZN |
| Waltheria | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Walwhalleya | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Wamalchitamia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Wambalana | Euonychophora | Reid (1996) | Peripatopsidae. | ICZN |
| Waminoa | Acoela | Hooge (2003) | . | ICZN |
| Wandonia | Flavobacteriales | Lee et al. (2010) | . | ICNB |
| Wangenheimia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Wangia | Flavobacteriales | Qin et al. (2007) | Later homonym. Replaced by Zunongwangia (see Validation list no. 116). | ICNB |
| Wangiella | Tintinnida | Lynn (2008) | . | ICZN |
| Warburgia | Canellales | Mabberley (2008) | Canellaceae. | ICBN |
| Warburgiella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Wardia | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Wardia | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Warea | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Warionia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Warmingia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Warneckea | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Warnockia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Warnowia | Gymnodiniales | Fensome et al. (1993) | . | ICBN |
| Warnstorfia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Warrea | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Warreella | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Warrenia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Warrenita | Lituolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hormosinidae. | ICZN |
| Warreopsis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Warszewiczia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Washingtonia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Watanabea | | Neustupa et al. (2009); Darienko et al. (2010) | Domain Eucarya - Phylum Chlorophyta - Class Trebouxiophyceae. Watanabea-clade. | ICBN |
| Watsonia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Wautersia | Burkholderiales | Vaneechoutte et al. (2004) | . | ICNB |
| Wautersiella | Flavobacteriales | Kämpfer et al. (2006) | . | ICNB |
| Webbina | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nubeculariidae. | ICZN |
| Webbinella | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Polymorphinidae. | ICZN |
| Weberbauera | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Weberbauerella | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Weberbauerocereus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Weberella | Hadromerida | Boury-Esnault (2002) | . | ICZN |
| Weberocereus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Webervanbossea | Rhodymeniales | Schneider & Wynne (2007) | . | ICBN |
| Websteria | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Weddellina | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Wedelia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Weeksella | Flavobacteriales | Garrity et al. (2005) | . | ICNB |
| Weeksia | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Weelia | Salpida | van der Land (2001) | . | ICZN |
| Weigela | Dipsacales | Mabberley (2008) | Caprifoliaceae. | ICBN |
| Weinmannia | Oxalidales | Mabberley (2008) | Cunoniaceae. | ICBN |
| Weiseria | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Weisiopsis | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Weissella | Lactobacillales | Garrity et al. (2005) | . | ICNB |
| Weissia | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Weissiodicranum | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Welchiodendron | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Weldenia | Commelinales | Mabberley (2008) | Commelinaceae. | ICBN |
| Welfia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Wellheimia | Ochromonadales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Chromulinaceae (biflagellate). | ICBN |
| Wellmanellinella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Hauerinidae. | ICZN |
| Wellstedia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Welwitschia | Welwitschiales | Mabberley (2008); Christenhusz et al. (2011) | . | ICBN |
| Welwitschiella | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Wenchengia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Wendlandia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Wendlandiella | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Wendtia | Geraniales | Mabberley (2008) | Ledocarpaceae. | ICBN |
| Wenrichia | Peniculida | Lynn (2008) | Later synonym of Disematostoma?. | ICZN |
| Wenxinia | Rhodobacterales | Ying et al. (2007) | . | ICNB |
| Wenyonella | Eucoccidiorida | Perkins et al. (2000) | . | ICZN |
| Wenzelia | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Werauhia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Wercklea | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Werdermannia | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Werneria | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Werneria | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Werneriobryum | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Westiella | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Westiellopsis | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Westoniella | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Westringia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Wetherbeella | Nemastomatales | Schneider & Wynne (2007) | . | ICBN |
| Wetmorethraupis | Passeriformes | Clements (2007) | . | ICZN |
| Wetria | Malpighiales | Mabberley (2008) | Euphorbiaceae. | ICBN |
| Wettinia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Wettsteinia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Wettsteiniola | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Weymouthia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Whalleya | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Whidbeyella | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Whipplea | Cornales | Mabberley (2008) | Hydrangeaceae. | ICBN |
| Whiteochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Whiteodendron | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Whitesloanea | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Whitfieldia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Whitmorea | Icacinales | Mabberley (2008) | Icacinaceae. | ICBN |
| Whittonia | Saxifragales | Mabberley (2008) | Peridiscaceae. | ICBN |
| Whyanbeelia | Malpighiales | Mabberley (2008) | Picrodendraceae. | ICBN |
| Whytockia | Lamiales | Mabberley (2008) | Gesneriaceae. | ICBN |
| Wiborgia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Widdringtonia | Cupressales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Widgrenia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Wiedomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Wielandia | Malpighiales | Mabberley (2008) | Phyllanthaceae. | ICBN |
| Wierzejskiella | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Wiesnerella | Marchantiales | Crandall-Stotler et al. (2009) | . | ICBN |
| Wiesnerella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Fischerinidae. | ICZN |
| Wiesneria | Alismatales | Mabberley (2008) | Alismataceae. | ICBN |
| Wiesnerina | Lagenida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Ellipsolagenidae. | ICZN |
| Wigandia | Boraginales | Mabberley (2008) | Boraginaceae. | ICBN |
| Wigginsia | Poecilosclerida | Hooper (2002) | . | ICZN |
| Wigglesworthia | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Wightia | Lamiales | Mabberley (2008) | Paulowniaceae. | ICBN |
| Wigrella | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Wigwamma | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | Papposphaeraceae ?. | ICBN |
| Wijkia | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Wijkiella | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Wijnhoffella | Reptantia | Gibson (1995) | . | ICZN |
| Wikstroemia | Malvales | Mabberley (2008) | Thymelaeaceae. | ICBN |
| Wilbertella | Chlamydodontida | Lynn (2008) | . | ICZN |
| Wilbertia | Pleuronematida | Fan et al. (2009) | . | ICZN |
| Wilbrandia | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Wildemania | Bangiales | Sutherland et al. (2011) | . | ICBN |
| Wildia | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Wilfredomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Wilhelmsia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Wilkesia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Wilkiea | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Willaertia | Schizopyrenida | Patterson et al. (2000) | . | ICZN |
| Willardia | Hadromerida | Rützler & Vacelet (2002) | . | ICZN |
| Willdenowia | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Willemetia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Willeya | Helminthomorpha | Benito (1982) | Spengelidae. | ICZN |
| Willia | Pottiales | Goffinet et al. (2009) | . | ICBN |
| Williamodendron | Laurales | Mabberley (2008) | Lauraceae. | ICBN |
| Williamsia | Corynebacteriales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Willisia | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Willkommia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Willkommlangea | Physarales | Yamamoto (1998) | . | ICBN |
| Willughbeia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Wilsonaea | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Wilsonia | Passeriformes | Clements (2007) | . | ICZN |
| Wilsonia | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Wilsoniana | Albuginales | Thines & Spring (2005) | . | ICBN |
| Wilsoniella | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Wimmerella | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Wimmeria | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Wimveria | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Windsorina | Poales | Mabberley (2008) | Rapateaceae. | ICBN |
| Wingstrandarctus | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Winifredia | Poales | Mabberley (2008) | Restionaceae. | ICBN |
| Winklera | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Winklerella | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Winogradskyella | Flavobacteriales | Nedashkovskaya et al. (2005) | . | ICNB |
| Wiotkenia | Heteronemertea | Gibson (1995) | . | ICZN |
| Wislizenia | Brassicales | Mabberley (2008) | Cleomaceae. | ICBN |
| Wissadula | Malvales | Mabberley (2008) | Malvaceae. | ICBN |
| Wisteria | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Withania | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Witheringia | Solanales | Mabberley (2008) | Solanaceae. | ICBN |
| Witsenia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Wittmackanthus | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Wittmannia | Microsporida | Canning & Vavra (2000) | . | ICZN |
| Wittrockia | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Wittsteinia | Asterales | Mabberley (2008) | Alseuosmiaceae. | ICBN |
| Wobbilia | Placidiales | Cavalier-Smith & Chao (2006) | . | ICZN |
| Wodyetia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Woehleria | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Woelkerlingia | Ceramiales | Wynne & Schneider (2010) | . | ICBN |
| Wohlfahrtiimonas | Xanthomonadales | Tóth et al. (2008) | . | ICNB |
| Wolbachia | Rickettsiales | Garrity et al. (2005) | . | ICNB |
| Wolffhugelia | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Wolffia | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Wolffiella | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Wolfkosia | Nassulida | Lynn (2008) | . | ICZN |
| Wolga | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Wolinella | Campylobacterales | Garrity et al. (2005) | . | ICNB |
| Wollastoniella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Wollea | Nostocales | Hoffmann et al. (2005) | . | ICBN |
| Wollemia | Araucariales | Farjon (2001); Christenhusz et al. (2011) | . | ICBN |
| Woloszynskia | Gymnodiniales | Fensome et al. (1993) | . | ICBN |
| Wolskana | Entodiniomorphida | Lynn (2008) | . | ICZN |
| Wolskyella | Synechococcales | Hoffmann et al. (2005); Yamagishi (2007) | "Wilskyella" in Hoffmann et al. (2005) is misspelling. | ICBN |
| Wolterstorffina | Anura | Vitt & Caldwell (2009) | Bufonidae. | ICZN |
| Womersleya | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Womersleyella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Woodburnia | Apiales | Mabberley (2008) | Araliaceae. | ICBN |
| Woodfordia | Passeriformes | Clements (2007) | . | ICZN |
| Woodfordia | Myrtales | Mabberley (2008) | Lythraceae. | ICBN |
| Woodia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Woodiellantha | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Woodruffia | Platyophryida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Woodruffides | Platyophryida | Lynn (2008); Foissner et al. (2011) | . | ICZN |
| Woodsholea | | Abraham et al. (2004); Williams et al. (2007) | Domain Bacteria - Phylum Proteobacteria - Class Alphaproteobacteria. Hyphomonadaceae. | ICNB |
| Woodsia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Woodwardia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Wooleya | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Woollsia | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Woronichinia | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Woronichiniella | Ochromonadales | Kristiansen & Preisig (2001); Cavalier-Smith & Chao (2006) | Dinobryaceae (uniflagellate). | ICBN |
| Woronina | Plasmodiophorida | Cavalier-Smith (1993); Kirk et al. (2008) | . | ICZN |
| Worsleya | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Woytkowskia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Wrangelia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Wrightella | Alcyonacea | Bayer (1981) | Melithaeidae. | ICZN |
| Wrightia | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Wrightiella | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Wrixonia | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Wulfenia | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Wulfeniopsis | Lamiales | Mabberley (2008) | Plantaginaceae. | ICBN |
| Wulfertia | Ploima | Segers (2002); Segers (2007) | . | ICZN |
| Wulguru | Acoela | Hooge (2003); Hooge & Tyler (2005) | . | ICZN |
| Wullschlaegelia | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Wunderlichia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Wurdackanthus | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Wurdastom | Myrtales | Mabberley (2008) | Melastomataceae. | ICBN |
| Wurdemannia | Gigartinales | Schneider & Wynne (2007) | . | ICBN |
| Wurmbea | Liliales | Mabberley (2008) | Colchicaceae. | ICBN |
| Wuvula | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Wyethia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Wyulda | Australidelphia | McKenna & Bell (1997) | . | ICZN |
| X | |
| Xandarodinium | Peridiniales | Fensome et al. (1993) | Holocene. | ICBN |
| Xantheranthemum | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Xanthidium | Desmidiales | Gontcharov (2008) | . | ICBN |
| Xanthisma | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xanthium | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xanthobacter | Rhizobiales | Garrity et al. (2005) | . | ICNB |
| Xanthocephalum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xanthocephalus | Passeriformes | Clements (2007) | . | ICZN |
| Xanthoceras | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Xanthocercis | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Xanthocyparis | Cupressales | Mill & Farjon (2006); Mabberley (2008); Adams et al. (2009); Debreczy et al. (2009); Eckenwalder (2009); Christenhusz et al. (2011) | Christenhusz et al. (2011) treated Xanthocyparis as a later synonym of Cupressus. | ICBN |
| Xanthomonas | Xanthomonadales | Garrity et al. (2005) | . | ICNB |
| Xanthomyrtus | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Xanthomyza | Passeriformes | Clements (2007) | . | ICZN |
| Xanthonema | Tribonematales | Ettl (1978); Silva (1979) | Substitute name for "Heterothrix". | ICBN |
| Xanthopappus | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xanthophyllum | Fabales | Mabberley (2008) | Polygalaceae. | ICBN |
| Xanthophytum | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Xanthopsar | Passeriformes | Clements (2007) | . | ICZN |
| Xanthorhiza | Ranunculales | Mabberley (2008) | Ranunculaceae. | ICBN |
| Xanthorrhoea | Asparagales | Mabberley (2008) | Xanthorrhoeaceae. | ICBN |
| Xanthosia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Xanthosoma | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Xanthostemon | Myrtales | Mabberley (2008) | Myrtaceae. | ICBN |
| Xanthotis | Passeriformes | Clements (2007) | . | ICZN |
| Xantolis | Ericales | Mabberley (2008) | Sapotaceae. | ICBN |
| Xantonnea | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Xantonneopsis | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Xantusia | Squamata | Vitt & Caldwell (2009) | Xantusiidae. | ICZN |
| Xatardia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Xema | Charadriiformes | Clements (2007) | . | ICZN |
| Xenagama | Squamata | Vitt & Caldwell (2009) | Agamidae. | ICZN |
| Xenelaphis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xenerpestes | Passeriformes | Clements (2007) | . | ICZN |
| Xenia | Alcyonacea | Bayer (1981) | Xeniidae. | ICZN |
| Xenia | Caryophyllales | Mabberley (2008) | Portulacaceae. | ICBN |
| Xenicus | Passeriformes | Clements (2007) | . | ICZN |
| Xenikophyton | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Xenoarmaueria | Pelagica | Gibson (1995) | . | ICZN |
| Xenobranchion | Phlebobranchia | Monniot & Monniot (1972); Monniot (2001) | Corellidae. | ICZN |
| Xenocalamus | Squamata | Vitt & Caldwell (2009) | Serpentes. Atractaspididae. | ICZN |
| Xenocephalozia | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Xenochila | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Xenochrophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xenococcus | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Xenocopsychus | Passeriformes | Clements (2007) | . | ICZN |
| Xenodacnis | Passeriformes | Clements (2007) | . | ICZN |
| Xenodasys | Macrodasyida | Hummon & Todaro (2010) | . | ICZN |
| Xenodermus | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xenodon | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xenoglaux | Strigiformes | Clements (2007) | . | ICZN |
| Xenogorgia | Alcyonacea | Bayer (1981) | Chrysogorgiidae. | ICZN |
| Xenohaliotis | Rickettsiales | Garrity et al. (2005) | . | ICNB |
| Xenohyla | Anura | Vitt & Caldwell (2009) | Hylidae. | ICZN |
| Xenokrohnia | Phragmophora | Casanova (1985); Casanova (1993) | Heterokrohniidae. Now checking. | ICZN |
| Xenoligea | Passeriformes | Clements (2007) | . | ICZN |
| Xenomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Xenonemertes | Reptantia | Gibson (1995); Kajihara et al. (2008) | Junior synonym of Punnettia. | ICZN |
| Xenopeltis | Squamata | Vitt & Caldwell (2009) | Serpentes. Xenopeltidae. | ICZN |
| Xenoperdix | Galliformes | Clements (2007) | . | ICZN |
| Xenophidion | Squamata | Vitt & Caldwell (2009) | Serpentes. "Tropidophiidae". | ICZN |
| Xenophilus | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Xenopholis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xenophrys | Anura | Vitt & Caldwell (2009) | Megophryidae. | ICZN |
| Xenophyllum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xenopipo | Passeriformes | Clements (2007) | . | ICZN |
| Xenopirostris | Passeriformes | Clements (2007) | . | ICZN |
| Xenopleura | Helminthomorpha | Benito (1982) | Harrimaniidae. | ICZN |
| Xenops | Passeriformes | Clements (2007) | . | ICZN |
| Xenopsaris | Passeriformes | Clements (2007) | . | ICZN |
| Xenopus | Anura | Vitt & Caldwell (2009) | Pipidae. | ICZN |
| Xenorhabdus | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Xenorhina | Anura | Vitt & Caldwell (2009) | Microhylidae. | ICZN |
| Xenornis | Passeriformes | Clements (2007) | . | ICZN |
| Xenosaurus | Squamata | Vitt & Caldwell (2009) | Xenosauridae. | ICZN |
| Xenoscapa | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Xenospingus | Passeriformes | Clements (2007) | . | ICZN |
| Xenospiza | Passeriformes | Clements (2007) | . | ICZN |
| Xenospongia | Hadromerida | Sarà (2002) | . | ICZN |
| Xenostegia | Solanales | Mabberley (2008) | Convolvulaceae. | ICBN |
| Xenothallus | Fossombroniales | He-Nygrén et al. (2006); Crandall-Stotler et al. (2009) | . | ICBN |
| Xenothekella | Allogromiida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Allogromiidae. | ICZN |
| Xenotholos | Chroococcales | Hoffmann et al. (2005) | . | ICBN |
| Xenotriccus | Passeriformes | Clements (2007) | . | ICZN |
| Xenotrichula | Chaetonotida | Balsamo et al. (2009); Hummon & Todaro (2010) | . | ICZN |
| Xenoturbella | Xenoturbellida | Bourlat et al. (2006) | . | ICZN |
| Xenotyphlops | Squamata | Vitt & Caldwell (2009) | Serpentes. Typhlopidae. | ICZN |
| Xenoxybelis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xenuromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Xenus | Charadriiformes | Clements (2007) | . | ICZN |
| Xeranthemum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xeroaloysia | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Xerochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Xerochrysum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xerocladia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Xeroderris | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Xerodraba | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Xerolekia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xerolirion | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Xeromys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Xeronema | Asparagales | Mabberley (2008) | Xeronemataceae. | ICBN |
| Xerophyllum | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Xerophyta | Pandanales | Mabberley (2008) | Velloziaceae. | ICBN |
| Xerorchis | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Xerosicyos | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Xerosiphon | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Xerospermum | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Xerospiraea | Rosales | Mabberley (2008) | Rosaceae. | ICBN |
| Xerothamnella | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Xerotia | Caryophyllales | Mabberley (2008) | Caryophyllaceae. | ICBN |
| Xerus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Xerxes | Poales | Mabberley (2008) | Bromeliaceae. | ICBN |
| Xestospongia | Haplosclerida | Desqueyroux-Faúndez & Valentine (2002) | . | ICZN |
| Ximenia | Santalales | Mabberley (2008) | Olacaceae. | ICBN |
| Xiphacantha | Arthracanthida | Febvre et al. (2000) | . | ICZN |
| Xiphidiopicus | Piciformes | Clements (2007) | . | ICZN |
| Xiphidium | Commelinales | Mabberley (2008) | Haemodoraceae. | ICBN |
| Xiphinematobacter | Chthoniobacterales | Garrity et al. (2005); Ludwig et al. (2011); Vandekerckhove et al. (2011) | Not validly published (Candidatus). | ICNB |
| Xiphirhynchus | Passeriformes | Clements (2007) | . | ICZN |
| Xiphocephalus | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Xiphochaeta | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xiphocolaptes | Passeriformes | Clements (2007) | . | ICZN |
| Xipholena | Passeriformes | Clements (2007) | . | ICZN |
| Xiphopterella | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Xiphorhynchus | Passeriformes | Clements (2007) | . | ICZN |
| Xiphotheca | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Xolmis | Passeriformes | Clements (2007) | . | ICZN |
| Xolocotzia | Lamiales | Mabberley (2008) | Verbenaceae. | ICBN |
| Xylanche | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Xylanibacter | Bacteroidales | Ueki et al. (2006) | . | ICNB |
| Xylanibacterium | Micrococcales | Rivas et al. (2004); Ludwig et al. (2012) | . | ICNB |
| Xylanimicrobium | Micrococcales | Stackebrandt & Schumann (2004); Ludwig et al. (2012) | . | ICNB |
| Xylanimonas | Micrococcales | Garrity et al. (2005); Ludwig et al. (2012) | . | ICNB |
| Xylanthemum | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xylella | Xanthomonadales | Garrity et al. (2005) | . | ICNB |
| Xylia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Xylobium | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Xylocalyx | Lamiales | Mabberley (2008) | Orobanchaceae. | ICBN |
| Xylocarpus | Sapindales | Mabberley (2008) | Meliaceae. | ICBN |
| Xylochloris | | Neustupa et al. (2011) | Domain Eucarya - Phylum Chlorophyta - Class Trebouxiophyceae. | ICBN |
| Xylolejeunea | Porellales | Crandall-Stotler et al. (2009) | . | ICBN |
| Xylomelum | Proteales | Mabberley (2008) | Proteaceae. | ICBN |
| Xylonagra | Myrtales | Mabberley (2008) | Onagraceae. | ICBN |
| Xylonymus | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Xyloolaena | Malvales | Mabberley (2008) | Sarcolaenaceae. | ICBN |
| Xylophilus | Burkholderiales | Garrity et al. (2005) | . | ICNB |
| Xylophis | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Xylophragma | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Xylopia | Magnoliales | Mabberley (2008) | Annonaceae. | ICBN |
| Xylopodia | Cornales | Mabberley (2008) | Loasaceae. | ICBN |
| Xylorhiza | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xylosalsola | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Xylosma | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Xylothamia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Xylotheca | Malpighiales | Mabberley (2008) | Achariaceae. | ICBN |
| Xymalos | Laurales | Mabberley (2008) | Monimiaceae. | ICBN |
| Xyris | Poales | Mabberley (2008) | Xyridaceae. | ICBN |
| Xyropteris | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Xysmalobium | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Xystonella | Tintinnida | Lynn (2008) | . | ICZN |
| Xystonellopsis | Tintinnida | Lynn (2008) | . | ICZN |
| Y | |
| Yabea | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Yagiua | Philasterida | Lynn (2008) | Nomen nudum. | ICZN |
| Yakirra | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Yakovia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Yamadaea | Corallinales | Schneider & Wynne (2007) | . | ICBN |
| Yamadaella | Nemaliales | Schneider & Wynne (2007) | . | ICBN |
| Yamagutisentis | Echinorhynchida | Amin (1985) | . | ICZN |
| Yangia | Rhodobacterales | Dai et al. (2006) | . | ICNB |
| Yania | Micrococcales | Li et al. (2004); Li et al. (2008) | Later homonym. Replaced by Yaniella. | ICNB |
| Yaniella | Micrococcales | Li et al. (2008); Ludwig et al. (2012) | . | ICNB |
| Yanomamua | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Yatabella | Gelidiales | Schneider & Wynne (2007) | Later synonym of Acanthopeltis. | ICBN |
| Yavia | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Yeatesia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Yendonia | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Yeosuana | Flavobacteriales | Kwon et al. (2006) | . | ICNB |
| Yermo | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Yersinia | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Yesevius | Gonyaulacales | Fensome et al. (1993); Özdikmen (2009); Nakada (2010) | Later synonym of Heteraulacus. | ICBN |
| Yimella | Micrococcales | Tang et al. (2010); Ludwig et al. (2012) | Dermacoccaceae. | ICNB |
| Yinia | Heteronemertea | Kajihara et al. (2008) | Junior homonym. Replaced by Yininemertes. | ICZN |
| Yininemertes | Heteronemertea | Kajihara et al. (2008) | Replacement name for Yinia. | ICZN |
| Yinshania | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Yoania | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Yoda | Helminthomorpha | Priede et al. (2012) | Torquaratoridae. | ICZN |
| Yokenella | Enterobacteriales | Garrity et al. (2005) | . | ICNB |
| Yonagunia | Cryptonemiales | Silva (2002); Schneider & Wynne (2007) | . | ICBN |
| Yonedaella | Oscillatoriales | Hoffmann et al. (2005) | . | ICBN |
| Yonghaparkia | Micrococcales | Yoon et al. (2006); Ludwig et al. (2012) | . | ICNB |
| Yoshidaphycus | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Youngia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Ypsilandra | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Ypsilopus | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Yucatania | Astrophorida | Gómez (2006) | . | ICZN |
| Yucca | Asparagales | Mabberley (2008) | Asparagaceae. | ICBN |
| Yuhina | Passeriformes | Clements (2007) | . | ICZN |
| Yuhushiella | Pseudonocardiales | Mao et al. (2011); Ludwig et al. (2012) | Pseudonocardiaceae. | ICNB |
| Yungasocereus | Caryophyllales | Mabberley (2008) | Cactaceae. | ICBN |
| Yushania | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Yuzurua | Ceramiales | Wynne & Schneider (2010) | . | ICBN |
| Yvesia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Z | |
| Zacateza | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Zachaenus | Anura | Vitt & Caldwell (2009) | Cycloramphidae. | ICZN |
| Zachariasia | Stylonematales | Schneider & Wynne (2007); Wynne & Schneider (2010) | Later synonym of Chroothece. | ICBN |
| Zaedyus | Xenarthra | McKenna & Bell (1997) | . | ICZN |
| Zaglossus | Monotremata | McKenna & Bell (1997) | . | ICZN |
| Zaleya | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Zalophus | Carnivora | McKenna & Bell (1997) | . | ICZN |
| Zaluzania | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zaluzianskya | Lamiales | Mabberley (2008) | Scrophulariaceae. | ICBN |
| Zameioscirpus | Poales | Mabberley (2008) | Cyperaceae. | ICBN |
| Zameus | Squaliformes | Nelson (2006) | . | ICZN |
| Zamia | Cycadales | Mabberley (2008); Christenhusz et al. (2011) | . | ICBN |
| Zamioculcas | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Zanclea | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Zanclella | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Zancleopsis | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Zanclonia | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Zandera | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zanderia | Dicranales | Goffinet et al. (2009) | . | ICBN |
| Zanha | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Zaninettia | Carterinida | Kaminski (2000) | Zaninettiinae. | ICZN |
| Zannichellia | Alismatales | Mabberley (2008) | Potamogetonaceae. | ICBN |
| Zanobatus | Myliobatiformes | Nelson (2006) | . | ICZN |
| Zanonia | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Zantedeschia | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Zanthoxylum | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Zaocys | Squamata | Vitt & Caldwell (2009) | Serpentes. "Colubridae". | ICZN |
| Zaolutus | Actiniaria | Fautin et al. (2007) | . | ICZN |
| Zapoteca | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zapteryx | Rajiformes | Nelson (2006) | . | ICZN |
| Zapus | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Zaratornis | Passeriformes | Clements (2007) | . | ICZN |
| Zataria | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Zavarzinella | Planctomycetales | Kulichevskaya et al. (2009) | . | ICNB |
| Zavarzinia | Rhodospirillales | Garrity et al. (2005) | . | ICNB |
| Zavattariornis | Passeriformes | Clements (2007) | . | ICZN |
| Zavodovskina | Trochamminida | Kaminski (2000) | Zavodovskininae, Trochamminacea. | ICZN |
| Zea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zeaflorilus | Rotaliida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Nonionidae. | ICZN |
| Zeaxanthinibacter | Flavobacteriales | Asker et al. (2007) | . | ICNB |
| Zebrilus | Ciconiiformes | Clements (2007) | . | ICZN |
| Zehnderia | Malpighiales | Mabberley (2008) | Podostemaceae. | ICBN |
| Zehneria | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Zeledonia | Passeriformes | Clements (2007) | . | ICZN |
| Zelenkoa | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Zelinkaderes | Cyclorhagida | Higgins (1990) | . | ICZN |
| Zelinkiella | Bdelloida | Segers (2002); Segers (2007) | . | ICZN |
| Zelkova | Rosales | Mabberley (2008) | Ulmaceae. | ICBN |
| Zellera | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Zelleriella | Opalinales | Delvinquier & Patterson (2000) | . | ICZN |
| Zelometeorium | Hypnales | Goffinet et al. (2009) | . | ICBN |
| Zelotomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Zelounies | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Zeltnera | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Zemisia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zenaida | Columbiformes | Clements (2007) | . | ICZN |
| Zenia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zenkerella | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Zenkerella | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zenkeria | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zenobia | Ericales | Mabberley (2008) | Ericaceae. | ICBN |
| Zephyra | Asparagales | Mabberley (2008) | Tecophilaeaceae. | ICBN |
| Zephyranthes | Asparagales | Mabberley (2008) | Amaryllidaceae. | ICBN |
| Zeravschania | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Zerdana | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Zeugandra | Asterales | Mabberley (2008) | Campanulaceae. | ICBN |
| Zeugites | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zeuktophyllum | Caryophyllales | Mabberley (2008) | Aizoaceae. | ICBN |
| Zeuxine | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Zexmenia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zeyheria | Lamiales | Mabberley (2008) | Bignoniaceae. | ICBN |
| Zeylanocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Zeylonechinorhynchus | Neoechinorhynchida | Amin (1985) | . | ICZN |
| Zhangella | Rhizobiales | Xu et al. (2009) | . | ICNB |
| Zhangiella | Anthoathecata | Bouillon et al. (2006) | . | ICZN |
| Zhaoermia | Squamata | Vitt & Caldwell (2009) | Serpentes. Viperidae. | ICZN |
| Zhihengliuella | Micrococcales | Zhang et al. (2007); Ludwig et al. (2012) | . | ICNB |
| Zhongshania | | Li et al. (2011) | Domain Bacteria - Phylum Proteobacteria - Class Gammaproteobacteria. | ICNB |
| Zhouia | Flavobacteriales | Liu et al. (2006) | . | ICNB |
| Zhumeria | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Zieria | Sapindales | Mabberley (2008) | Rutaceae. | ICBN |
| Zigadenus | Liliales | Mabberley (2008) | Melanthiaceae. | ICBN |
| Zilla | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Zimmerius | Passeriformes | Clements (2007) | . | ICZN |
| Zimmermannella | Micrococcales | Lin et al. (2004); Evtushenko (2012) | Later synonym of Pseudoclavibacter. | ICNB |
| Zinarmaueria | Pelagica | Gibson (1995) | . | ICZN |
| Zingeria | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zingiber | Zingiberales | Mabberley (2008) | Zingiberaceae. | ICBN |
| Zinnia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zinovaea | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Zinowiewia | Celastrales | Mabberley (2008) | Celastraceae. | ICBN |
| Zioella | Arthrotardigrada | Kinchin (1994) | . | ICZN |
| Ziphius | Cetartiodactyla | McKenna & Bell (1997); Murphy et al. (2001) | Cetacea. | ICZN |
| Zippelia | Piperales | Mabberley (2008) | Piperaceae. | ICBN |
| Zivkovicia | Arcellinida | Meisterfeld (2000) | Difflugina -- Difflugiidae. | ICZN |
| Zizania | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zizaniopsis | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zizia | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Ziziphora | Lamiales | Mabberley (2008) | Labiatae. | ICBN |
| Ziziphus | Rosales | Mabberley (2008) | Rhamnaceae. | ICBN |
| Zoanthus | Zoanthidea | Sinniger et al. (2005) | . | ICZN |
| Zobellella | Aeromonadales | Kin & Shieh (2006) | . | ICNB |
| Zobellia | Flavobacteriales | Garrity et al. (2005) | . | ICNB |
| Zodionemertes | Heteronemertea | Gibson (1995) | . | ICZN |
| Zoegea | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zollernia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zollingeria | Sapindales | Mabberley (2008) | Sapindaceae. | ICBN |
| Zombia | Arecales | Mabberley (2008) | Palmae. | ICBN |
| Zombitsia | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Zomicarpa | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Zomicarpella | Alismatales | Mabberley (2008) | Araceae. | ICBN |
| Zonanthus | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Zonariophila | Ceramiales | Schneider & Wynne (2007) | . | ICBN |
| Zonerodius | Ciconiiformes | Clements (2007) | . | ICZN |
| Zonomyxa | Arcellinida | Meisterfeld (2000) | Arcellina -- Microcoryciidae. | ICZN |
| Zonosagitta | Aphragmophora | Bieri (1991) | Sagittidae. | ICZN |
| Zonosaurus | Squamata | Vitt & Caldwell (2009) | Cordylidae. | ICZN |
| Zonotriche | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zonotrichia | Passeriformes | Clements (2007) | . | ICZN |
| Zonotrichium | Haptorida | Lynn (2008) | . | ICZN |
| Zoogloea | Rhodocyclales | Garrity et al. (2005) | . | ICNB |
| Zoonavena | Apodiformes | Clements (2007) | . | ICZN |
| Zoopilus | Scleractinia | Cairns et al. (1999); Veron (2000) | . | ICZN |
| Zoopsidella | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Zoopsis | Jungermanniales | Crandall-Stotler et al. (2009) | . | ICBN |
| Zoorhabdella | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae. | ICBN |
| Zooshikella | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Zoothamnioides | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Zoothamnium | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Zoothamnopsis | Peritrichida | Lynn (2008); Zhan et al. (2009) | . | ICZN |
| Zoothera | Passeriformes | Clements (2007) | . | ICZN |
| Zootoca | Squamata | Vitt & Caldwell (2009) | Lacertidae. | ICZN |
| Zooxanthella | | Fensome et al. (1993) | Domain Eucarya - Phylum Dinozoa - Class Dinophyceae. | ICBN |
| Zornia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zosima | Apiales | Mabberley (2008) | Umbelliferae. | ICBN |
| Zostera | Alismatales | Mabberley (2008) | Zosteraceae. | ICBN |
| Zosterella | Commelinales | Mabberley (2008) | Pontederiaceae. | ICBN |
| Zosterodasys | Synhymeniida | Lynn (2008) | . | ICZN |
| Zosterops | Passeriformes | Clements (2007) | . | ICZN |
| Zotovia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zoyaella | Miliolida | Loeblich Jr. & Tappan (1988); Loeblich Jr. & Tappan (1992) | Fischerinidae. | ICZN |
| Zoysia | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zschokkella | Bivalvulida | Lom & Dyková (2006) | . | ICZN |
| Zuccagnia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zuccarinia | Gentianales | Mabberley (2008) | Rubiaceae. | ICBN |
| Zuckia | Caryophyllales | Mabberley (2008) | Amaranthaceae. | ICBN |
| Zuelania | Malpighiales | Mabberley (2008) | Salicaceae. | ICBN |
| Zuloagaea | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zunongwangia | Flavobacteriales | Qin et al. (2007) | Corrected name of "Wangia".. | ICNB |
| Zuvanda | Brassicales | Mabberley (2008) | Cruciferae. | ICBN |
| Zygabikodinium | Peridiniales | Fensome et al. (1993) | . | ICBN |
| Zygaspis | Squamata | Vitt & Caldwell (2009) | Amphisbaenidae. | ICZN |
| Zygeupolia | Heteronemertea | Gibson (1995) | . | ICZN |
| Zygia | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zygnema | Zygnematales | Gontcharov (2008) | . | ICBN |
| Zygnemopsis | Zygnematales | Gontcharov (2008) | . | ICBN |
| Zygocanna | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Zygocarpon | Fabales | Mabberley (2008) | Leguminosae. | ICBN |
| Zygochloa | Poales | Mabberley (2008) | Gramineae. | ICBN |
| Zygocircus | Nassellaria | Anderson et al. (2000) | . | ICZN |
| Zygocystis | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Zygodon | Orthotrichales | Goffinet et al. (2009) | . | ICBN |
| Zygodontomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Zygogeomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Zygogonium | Zygnematales | Gontcharov (2008) | . | ICBN |
| Zygogynum | Canellales | Mabberley (2008) | Winteraceae. | ICBN |
| Zygonemertes | Eumonostilifera | Gibson (1995); Chernyshev (2003) | . | ICZN |
| Zygopetalum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Zygophlebia | Polypodiales | Christenhusz et al. (2011) | . | ICBN |
| Zygophylax | Leptothecata | Bouillon et al. (2006) | . | ICZN |
| Zygophyllum | Zygophyllales | Mabberley (2008) | Zygophyllaceae. | ICBN |
| Zygoruellia | Lamiales | Mabberley (2008) | Acanthaceae. | ICBN |
| Zygosepalum | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Zygosicyos | Cucurbitales | Mabberley (2008) | Cucurbitaceae. | ICBN |
| Zygosoma | Eugregarinorida | Perkins et al. (2000) | . | ICZN |
| Zygosphaera | Coccolithales | Jordan et al. (2004); Edvardsen & Medlin (2007) | former Calyptrosphaeraceae. | ICBN |
| Zygostates | Asparagales | Mabberley (2008) | Orchidaceae. | ICBN |
| Zygostaurus | Arthracanthida | Febvre et al. (2000) | . | ICZN |
| Zygostelma | Gentianales | Mabberley (2008) | Apocynaceae. | ICBN |
| Zygostigma | Gentianales | Mabberley (2008) | Gentianaceae. | ICBN |
| Zygotritonia | Asparagales | Mabberley (2008) | Iridaceae. | ICBN |
| Zymobacter | Oceanospirillales | Garrity et al. (2005) | . | ICNB |
| Zymomonas | Sphingomonadales | Garrity et al. (2005) | . | ICNB |
| Zymophilus | Selenomonadales | Garrity et al. (2005); Marchandin et al. (2010) | . | ICNB |
| Zymurgia | Cryptonemiales | Silva (2002); Schneider & Wynne (2007) | . | ICBN |
| Zyrphelis | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zyzomys | Rodentia | McKenna & Bell (1997) | . | ICZN |
| Zyzyxia | Asterales | Mabberley (2008) | Compositae. | ICBN |
| Zyzzya | Poecilosclerida | Hooper (2002) | . | ICZN |
| Zyzzyzus | Anthoathecata | Bouillon et al. (2006) | . | ICZN |