A genus (/ˈdʒiːnəs/, pl. genera /ˈdʒɛnərə/) is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
monophyly – all descendants of an ancestral taxon are grouped
together (i.e. phylogenetic analysis should clearly demonstrate both
monophyly and validity as a separate lineage).
reasonable compactness – a genus should not be expanded needlessly;
distinctness – with respect to evolutionarily relevant criteria,
i.e. ecology, morphology, or biogeography;
1 Etymology 2 Use
2.1 Use in nomenclature 2.2 The type concept 2.3 Categories of generic name 2.4 Identical names (homonyms) 2.5 Use in higher classifications
3 Numbers of accepted genera
The term "genus" comes from the
The scientific name (or the scientific epithet) of a genus is also
called the generic name; it is always capitalised. It plays a
fundamental role in binomial nomenclature, the system of naming
organisms, where it is combined with the scientific name of a species:
Specific name (botany)
Use in nomenclature
Main articles: Binomial nomenclature, Taxonomy (biology), Author
citation (zoology), and Author citation (botany)
The rules for the scientific names of organisms are laid down in the
Nomenclature Codes, which allow each species a single unique name
that, for "animals" (including protists), "plants" (also including
algae and fungi) and prokaryotes (
The type concept See also: Type genus, Type species, and Type specimen Each genus should have a designated type, although in practice there is a backlog of older names without one. In zoology, this is the type species and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed.
Categories of generic name
In zoological usage, taxonomic names, including those of genera, are
classified as "available" or "unavailable". Available names are those
published in accordance with the International Code of Zoological
Nomenclature and not otherwise suppressed by subsequent decisions of
International Commission on Zoological Nomenclature (ICZN); the
earliest such name for any taxon (for example, a genus) should then be
selected as the "valid" (i.e., current or accepted) name for the taxon
Consequently, there will be more available names than valid names at
any point in time, which names are currently in use depending on the
judgement of taxonomists in either either combining taxa described
under multiple names, or splitting taxa which may bring available
names previously treated as synonyms back into use. "Unavailable"
names in zoology comprise names that either were not published
according to the provisions of the ICZN Code, or have subsequently
been suppressed, e.g., incorrect original or subsequent spellings,
names published only in a thesis, and generic names published after
1930 with no type species indicated.
In botany, similar concepts exist but with different labels. The
botanical equivalent of zoology's "available name" is a validly
published name. An invalidly published name is a nomen invalidum or
nom. inval.; a rejected name is a nomen rejiciendum or nom. rej.; a
later homonym of a validly published name is a nomen illegitimum or
nom. illeg.; for a full list refer the International Code of
Nomenclature for algae, fungi, and plants (ICNafp) and the work cited
above by Hawksworth, 2010. In place of the "valid taxon" in
zoology, the nearest equivalent in botany is "correct name" or
"current name" which can, again, differ or change with alternative
taxonomic treatments or new information that results in previously
accepted genera being combined or split.
Prokaryote and virus Codes of Nomenclature also exist which serve as a
reference for designating currently accepted genus names as opposed to
others which may be either reduced to synonymy, or, in the case of
prokaryotes, relegated to a status of "names without standing in
An available (zoological) or validly published (botanical) name that
has been historically applied to a genus but is not regarded as the
accepted (current/valid) name for the taxon is termed a synonym; some
authors also include unavailable names in lists of synonyms as well as
available names, such as misspellings, names previously published
without fulfilling all of the requirements of the relevant
nomenclatural Code, and rejected or suppressed names.
A particular genus name may have zero to many synonyms, the latter
case generally if the genus has been known for a long time and
redescribed as new by a range of subsequent workers, or if a range of
genera previously considered separate taxa have subsequently been
consolidated into one. For example, the World Register of Marine
Identical names (homonyms)
Within the same kingdom, one generic name can apply to one genus only.
However, many names have been assigned (usually unintentionally) to
two or more different genera. For example, the platypus belongs to the
genus Ornithorhynchus although
Anura is the name of the order of frogs but also is the name of a
non-current genus of plants;
Aotus is the generic name of both golden peas and night monkeys;
Oenanthe is the generic name of both wheatears and water dropworts;
Prunella is the generic name of both accentors and self-heal; and
Proboscidea is the order of elephants and the genus of devil's claws.
The name of the genus Paramecia (an extinct red alga) is also the
plural of the name of the genus
Use in higher classifications
The type genus forms the base for higher taxonomic ranks, such as the
Numbers of accepted genera
The numbers of either accepted, or all published genus names is not
known precisely although the latter value has been estimated by Rees
et al., 2017 at approximately 510,000 as at end 2016,
increasing at some 2,500 per year. "Official" registers of taxon names
at all ranks, including genera, exist for a few groups only such as
viruses and prokaryotes, while for others there
are compendia with no "official" standing such as Index Fungorum for
Fungi, Index Nominum Algarum and
AlgaeBase for algae, Index Nominum Genericorum
and the International Plant Names Index for plants in
general, and ferns through angiosperms, respectively, and Nomenclator
Zoologicus and the Index to
See also List of the largest genera of flowering plants References
^ a b "ICTV Taxonomy". International Committee on Taxonomy of Viruses. 2017. Retrieved May 29, 2018..mw-parser-output cite.citation font-style:inherit .mw-parser-output .citation q quotes:"""""""'""'" .mw-parser-output .citation .cs1-lock-free a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center .mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center .mw-parser-output .citation .cs1-lock-subscription a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center .mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration color:#555 .mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span border-bottom:1px dotted;cursor:help .mw-parser-output .cs1-ws-icon a background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center .mw-parser-output code.cs1-code color:inherit;background:inherit;border:inherit;padding:inherit .mw-parser-output .cs1-hidden-error display:none;font-size:100% .mw-parser-output .cs1-visible-error font-size:100% .mw-parser-output .cs1-maint display:none;color:#33aa33;margin-left:0.3em .mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format font-size:95% .mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left padding-left:0.2em .mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right padding-right:0.2em
^ Sigward, J. D.; Sutton, M. D.; Bennett, K. D. (2018). "How big is a genus? Towards a nomothetic systematics". Zoological Journal of the Linnean Society. 183 (2): 237–252. doi:10.1093/zoolinnean/zlx059.
^ Gill, F. B.; Slikas, B.; Sheldon, F. H. (2005). "Phylogeny of
titmice (Paridae): II.
^ a b de la Maza-Benignos, Mauricio; Lozano-Vilano, Ma. de Lourdes; García-Ramírez, María Elena (December 2015). "Response paper: Morphometric article by Mejía et al. 2015 alluding genera Herichthys and Nosferatu displays serious inconsistencies". Neotropical Ichthyology. 13 (4): 673–676. doi:10.1590/1982-0224-20150066.
^ Harper, Douglas. "genus". Online Etymology Dictionary.
^ Stuessy, T. F. (2009). Plant Taxonomy: The Systematic Evaluation of Comparative Data (2nd ed.). New York, New York, US: Columbia University Press. p. 42. ISBN 9780231147125.
^ a b D. L. Hawksworth (2010). Terms Used in Bionomenclature: The
^ World Register of Marine Species:
^ World Register of Marine Species: Pecten O. F. Müller, 1776
^ a b "IRMNG: Interim Register of Marine and Nonmarine Genera". www.irmng.org. Retrieved 2016-11-17.
^ Rees, Tony; Vandepitte, Leen; Decock, Wim; Vanhoorne, Bart (2017). "IRMNG 2006–2016: 10 Years of a Global Taxonomic Database". Biodiversity Informatics. 12: 1–44. doi:10.17161/bi.v12i0.6522.
^ List of Prokaryotic names with Standing in Nomenclature
^ Index Fungorum
^ Index Nominum Algarum
^ Index Nominum Genericorum
^ The International Plant Names Index
^ Nomenclator Zoologicus
^ Index to
^ Information: Catalogue of Life: 2018 Annual Checklist
^ Frodin, David G. (2004). "History and concepts of big plant genera". Taxon. 53 (3): 753–776. doi:10.2307/4135449. JSTOR 4135449.
^ Nicholson, K. E.; Crother, B. I.; Guyer, C.; Savage, J.M. (2012). "It is time for a new classification of anoles (Squamata: Dactyloidae)" (PDF). Zootaxa. 3477: 1–108.
External links Interim Register of Marine and Nonmarine Genera (IRMNG) Nomenclator Zoologicus: Index of all genus and subgenus names in zoological nomenclature from 1758 to 2004. Fauna Europaea Database for Taxonomy vteTaxonomic ranks
Realm (vir.) Subrealm (vir.) Domain/Superkingdom Kingdom Subkingdom Infrakingdom/Branch
Superphylum/Superdivision Phylum/Division Subphylum Infraphylum Microphylum
Superclass Class Subclass Infraclass Parvclass
Magnorder Superorder Order Suborder Infraorder Parvorder
Section (zoo.) Superfamily Family Subfamily Infrafamily
Supertribe Tribe Subtribe Infratribe
Genus Subgenus Section (bot.) Series (bot.)