Living organisms are known by scientific names. These binomial names can vary greatly in length, and some can be very short; genus or species names composed of only one letter are not allowed by any of the nomenclature codes, but any combination of two letters and above can be valid if it has not been previously used. This list of shortest species names lists the scientific binomials with the fewest letters. The longest scientific species names can be found in the list of long species names.
4 letters
Ia io Thomas, 1902 – Family Vespertilionidae. The great evening bat is the largest vespertilionid bat, reaching a wingspan of just over half a metre. It occurs in tropical Asia where it lives in limestone caves. Apart from being the shortest scientific name of a living organism (and one of the shortest possible, since anything below 4 letters would not be allowed), it also has the peculiarity of being composed only of vowels. The genus Ia (ἰά) is an ancient Greek term for 'voice', 'cry' or 'shout'; the specific name has commonly been assumed to refer to Io, a woman of classical mythology, viewed as "flighty;" but chiropterologist Thomas Griffiths has theorised that it is instead to be understood as the Latin interjection ĭō, meaning 'an exclamation of joy', and that therefore the correct English translation of the binomial would be 'Shout hurrah!'; Griffiths bolsters this argument by pointing out that Oldfield Thomas subsequently named another two species with the same word (Rhogeessa io and Balantiopteryx io), thus creating a succession of "three hurrahs", and proposes that this would be Thomas's way of celebrating his induction into the Royal Society in 1901, despite having no formal training.
†Yi qi Xu et al., 2015 – Family Scansoriopterygidae. This was a Jurassic theropod dinosaur that had an elongated finger which supported a patagium, akin to those of bats, which enabled the animal to glide between trees. The name is derived from Mandarin Chinese (翼 yì and 奇 qí, pronounced "ee chee"), meaning "strange wing".
5 letters
Aha ha Menke, 1977 – Family Crabronidae. This species of Australian wasp was named as a joke by entomologist Arnold Menke. He mentioned later that it was named for his exclamation "Aha, a new genus", when he first saw the specimen, with fellow entomologist Eric Grissell doubtfully responding "ha". It is found in the Kununurra region in Western Australia.
†Ano da and †Ano si - family Liberiblattinidae. Two fossil cockroaches from the Jurassic of Mongolia and Kazakhstan, respectively. The genus name Ano comes from áno, meaning "yes" in Slovak (it was described by a Slovak scientist). The specific epithet for the first is from da, Russian for "yes"; so the complete name means "Yes yes", but also "refers to ¥νoδoς (anodos): an electrode through which conventional current flows into a polarised electrical device." The epithet for the second comes from Slovak si, meaning "you are", so the complete name means "Yes, you are", or "Yes, you exist".
Foa fo – family Apogonidae. Known as weedy cardinalfish, this is a marine fish species of Indo-Pacific distribution, the type locality being the Philippines. Both the genus and species name derive from the word fo, Samoan for "cardinalfish".
†Hra na - family Liberiblattinidae. Another fossil cockroach, this time described from the Cretaceous of the Russian Far East. No etymological information was given, but the word hrana means "edge" in Slovak.
Ja ana S. Ueno, 1955 – Family Carabidae. This is a blind carabid from the Ja-Ana Cave near Gifu in southern Japan. However, the original genus Ja has been reclassified as a subgenus of Jujiroa, so its valid binomial name is currently Jujiroa ana (11 letters).
6 letters
Agra ce Erwin, 2010 – family Carabidae. One of more than 500 named species in the genus Agra of ground beetles; in this case, named after Terry Erwin's wife, Peruvian ornithologist Grace Servat.
†Ano ale , †Ano mal , †Ano net , †Ano nym , †Ano ona and †Ano tak - family Liberiblattinidae. Six more fossil cockroaches from the Jurassic and Cretaceous periods in the aforementioned genus Ano; ale is Slovak for "but", making the full name "Yes, but"; mal is Latin for "bad", and was given in reference to the deficent preservation state of the specimen; net is Russian for "no" (thus making the name "Yes no"); nym derives from Ancient Greek Ôνυμα (ónyma), meaning "name", and is used as wordplay and "also alluding to Nym server, a pseudonym server which provides untraceable email addresses"; ona is Slovak for "she", and was given in order to make the full name a palindrome; tak is Slovak for "so", making the complete name "Yes so".
Anu una – family Syrphidae. A hoverfly species endemic to New Zealand. Its palindromic name was constructed as just an arbitrary combination of letters.
†Beg tse Yu et al., 2020 – infraorder Neoceratopsia. A dinosaur from the early Cretaceous Period of Mongolia, named after the Himalayan deity Beg-tse, a god of war in pre-Buddhist Mongolian culture, often depicted with a rugose face and/or body, similar to the appearance of the preserved skull of the dinosaur.
Doto eo Ortea & Moro, 2014 – family Dotidae. A sea slug from the Canary Islands, Spain. Its specific epithet derives "from the Latin eo, to move from one place to another, alluding to the pot warp on which it was collected, an unstable environment that facilitates the passive movement of the species."
Ge geta de Nicéville, 1895 – family Hesperiidae. A skipper butterfly from Southeast Asia, the only species in genus Ge. No etymological explanation was given for its binomial name.
Gea eff Levi, 1983 – family Araneidae. An orb-weaver spider from New Guinea. It was given its unusual specific name because, even after it was identified as a distinct species, it remained for years without a proper description and was referred to in several papers simply as Argiope "F".
†Hra nie - family Liberiblattinidae. Another fossil cockroach from the Jurassic of Mongolia. Genus name Hra means "game" in Slovak, and nie means "no", but the complete word hranie means "playing".
Loa loa – family Onchocercidae. A filarial nematode (roundworm) that causes a disease called Loa loa filariasis or loiasis, one of the so-called neglected diseases. It is commonly known as the "African eye worm", as it localizes to the conjunctiva of the eye. It mainly inhabits rain forests in West Africa and has native origins in Ethiopia. It was originally described as Dracunculus loa, "loa" being the native word for this worm in the Congo and Gabon, and later transferred to newly created genus Loa.
†Ol xiai Vršanský & Wang, 2017 – family Olidae. An extinct cockroach with pectinate antennae, known from Cretaceous Burmese amber. Ol means "writing" in Santali language. In addition, this combination of letters looks like "01", which is used for a common abbreviation of optical lithography. Species name xiai is named after researcher Fangyuan Xia.
Poa fax – family Poaceae. This Australian grass has the shortest name of any plant. Poa () is Greek for "fodder", and fax is Latin for "torch" or "flame", referring to "its dense, spike-like inflorescence which resembles a torch with ascending tongues of flame". While the name Poa fax is accepted as valid by Flora of Australia, and some databases reflect this, such as POWO, WCSP and FloraBase, other sources such as Tropicos, WFO and GrassBase consider it a synonym, superseded by Neuropoa fax (J.H.Willis & Court) Clayton.
Tor tor – family Cyprinidae. The Tor mahseer of red-finned mahseer is a commercially important freshwater fish found in streams all over South Asia. It was originally described as Cyprinus tor; its species name derives from tora, a local name in the Ganges basin for mahseers. Subsequently, it was transferred to newly created genus Tor.
Zig zag - family Scincidae. A limbless skink from Madagascar, named "in reference to the very characteristic sinusoidal [ zigzag-shaped ] tracks left by this species when moving in the white sand."
7 letters
Aa erosa (Rchb.f.) Schltr. 1912, Aa macra Schltr. 1921 and Aa rosei Ames 1922 – family Orchidaceae. Three species of South American orchids that grow in the Andes. Genus Aa was erected in 1854 by Heinrich Gustav Reichenbach, apparently with the intention that it would always appear first in alphabetical listings. Another – disputed – explanation is that Reichenbach named this genus after Pieter van der Aa; the printer of the Dutch botanist Paul Hermann's Paradisus Batavus.
Acer yui – family Sapindaceae. An uncommon species of maple found only in the Gansu and Sichuan Provinces in western China.
Agra bci Erwin, 2000, Agra dax Erwin, 2000, Agra ega Erwin, 1982, Agra liv Erwin, 2002, Agra max Erwin, 2010, Agra nex Erwin, 2000, Agra not Erwin, 2002, Agra nox Erwin, 1984 and Agra pia Liebke 1940 – family Carabidae. Nine more species of Agra beetles, found in Central and South America. Agra bci is named after Barro Colorado Island, the type locality for this species. Agra dax is named after the Star Trek character Jadzia Dax, played by actress Terry Farrell. Agra ega is named after the former name of Tefé, the type locality for this species. Agra liv is named after actress Liv Tyler. Agra max is named after entomologist Max Liebke.
Betta pi Tan, 1998 – family Osphronemidae. A species of fighting fish found in well-shaded peat forest blackwater swamps and creeks in Thailand and Malaysia. The specific epithet comes from the Greek letter pi, as an allusion to the shape of its throat marking.
Bremia o Kontos & Thines - family Peronosporaceae. An oomycete found on the leaves of the smooth hawksbeard, Crepis capillaris. The specific epithet, which at one letter long is the shortest in existence, comes from "the Latin word 'o', referring to the astonishment about the diversity within the genus Bremia." Another Bremia species published in the same paper, Bremia krungthepmahanakhonamonrattanakosinmahintharayuthayamahadilokphopnoppharatratchathaniburiromudomratchaniwetmahasathanamonpimanawatansathitsakkathattiyawitsanukamprasitnonopsis, is the longest scientific name of any living or fossil organism, over twice as long as the previous record-holder. Article 23.2 of the International Code of Nomenclature for algae, fungi, and plants (Madrid Code), which governs the nomenclature of oomycetes, restricts the length of new specific epithets published on or after 1 January 2026 to between two and thirty letters; prior to this date, however, there were no official restrictions on their length—and these names were published just a few days before this rule came into effect, on 28 December 2025.
Car pini – family Caridae. An Australian weevil found on pine trees, hence the specific epithet pìni.
Cis afer , Cis fagi and Cis leoi – family Ciidae. Cis is a genus of minute tree-fungus beetles found all over the world. Cis afer, from South Africa (afer is Latin for "African"), is only known from the type specimens and no other record of it exists. In the case of Cis fagi, from Europe, its specific epithet alludes to its affinity to beech trees (genus Fagus), though it also occurs in many other types of trees, such as aspens, birches, oaks, willows, etc. Cis leoi, from Brazil, is dedicated to Léo Falqueto Vaz-de-Mello, the then-recently born son of a couple of colleagues of the scientists that described it.
Copa kei – family Corinnidae. A spider in the genus Copa found in South Africa. The epithet comes from its type locality: the town of Kei Mouth on the Great Kei River.
Cora imi – family Hygrophoraceae. A rare species of basidiolichen from Costa Rica, known only from the type collection, which was found at an altitude of about in the Los Santos Forest Reserve in Cerro de la Muerte. The specific epithet imi is an acronym for the International Mycological Institute.