zoological Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...

nomenclature, an available name is a

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

for a

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

of animals that has been published after 1757 and conforming to all the mandatory provisions of the

International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...

for the establishment of a zoological name. In contrast, an unavailable name is a name that does not conform to the rules of that code and that therefore is not available for use as a valid name for a

. Such a name does not fulfil the requirements in Articles 10 through 20 of the Code, or is excluded under Article 1.3.

Requirements

For a name to be available, in addition to meeting certain criteria for publication, there are a number of general requirements it must fulfill: it must include a description or definition of the taxon, must use only the

Latin alphabet The Latin alphabet, also known as the Roman alphabet, is the collection of letters originally used by the Ancient Rome, ancient Romans to write the Latin language. Largely unaltered except several letters splitting—i.e. from , and from � ...

, must be formulated within the

binomial nomenclature In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

framework, must be newly-proposed (not a redescription under the same name of a taxon previously made available) and originally used as a valid name rather than as a synonym, must not be for a

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

or hypothetical taxon, must not be for a taxon below the rank of subspecies, etc. In some rare cases, a name which does not meet these requirements may nevertheless be available, for historical reasons, as the criteria for availability have become more stringent with successive Code editions. For example, a name originally appearing along with an illustration but no formal description may be an available name, but only if the illustration was published prior to 1930 (under Article 12.2.7). All available names must refer to a

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

, even if one was not provided at the time the name was first proposed. For species-level names, the type is usually a single specimen (a

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

lectotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...

, or

neotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...

); for generic-level names, the type is a single species; for family-level names, the type is a single genus. This hierarchical system of typification provides a concrete empirical anchor for all zoological names. An available name is not necessarily a valid name, because an available name may be a

homonym In linguistics, homonyms are words which are either; '' homographs''—words that mean different things, but have the same spelling (regardless of pronunciation), or '' homophones''—words that mean different things, but have the same pronunciat ...

or subsequently be placed into

synonymy A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

. However, a valid name must always be an available one.

Unavailable names

Unavailable names include names that have not been published, such as "''

Oryzomys hypenemus ''Oryzomys'' is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (''O. palustris'') of the United States and ...

''" and "

Ubirajara jubatus "''Ubirajara''" ("lord of the spear") is an informal genus of compsognathid theropod that lived during the early Cretaceous period in what is now Brazil. The manuscript describing it was available online pre-publication but was never formally pu ...

", names without an accompanying description (''

nomina nuda Nomen may refer to: *Nomen gentilicium, the middle part of Ancient Roman names ** ''Nomen est omen'', a Latin quote about nominative determinism *Nomen (ancient Egypt), the personal name of Ancient Egyptian pharaohs *Jaume Nomen (born 1960), Catal ...

''), such as the subgeneric name ''Micronectomys'' proposed for the

Nicaraguan rice rat ''Oryzomys dimidiatus'', also known as the Nicaraguan oryzomys, Thomas's rice rat, or the Nicaraguan rice rat, is a rodent in the family Cricetidae. It is known from only three specimens, all collected in southeastern Nicaragua since 1904. Plac ...

, names proposed with a rank below that of

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

(

infrasubspecific name In biology, taxonomic rank (which some authors prefer to call nomenclatural rank because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of or ...

s), such as ''Sorex isodon princeps montanus'' for a form of the

taiga shrew The taiga shrew (''Sorex isodon''), also known as the even-toothed shrew can achieve a body length of about 67 millimeters, with a tail of about 43 millimeters. This shrew is very similar to the long-clawed shrew. This species inhabits forested ...

, and various other categories. Despite the frequent confusion caused by common sense, an unavailable name is not necessarily a ''

nomen nudum In Taxonomy (biology), taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published ...

''. A good examplification of this is the case of the unavailable

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

name "

", which was assumed by common sense to be a ''

'' before a detailed analysis of its nomenclatural status.

Contrast to botany

Under the

International Code of Nomenclature for algae, fungi, and plants The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN or ICNafp) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all tho ...

, this term is not used. In botany, the corresponding term is

validly published name In botanical nomenclature, a validly published name is a name that meets the requirements in the ''International Code of Nomenclature for algae, fungi, and plants'' (''ICN'') for valid publication. Valid publication of a name represents the minim ...

. The botanical equivalent of zoology's term "valid name" is

correct name In botany, the correct name according to the ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the one and only botanical name that is to be used for a particular taxon, when that taxon has a particular circumscription, p ...

References

Bibliography

*Hershkovitz, P. 1970. Supplementary notes on Neotropical ''Oryzomys dimidiatus'' and ''Oryzomys hammondi'' (Cricetinae). Journal of Mammalogy 51(4): 789-794. *Hutterer, R. & Zaitsev, M.V. 2004. Cases of homonymy in some Palaearctic and Nearctic taxa of the genus ''Sorex'' L. (Mammalia: Soricidae). Mammal Study 29:89-91. *International Commission for Zoological Nomenclature. 1999. International Code of Zoological Nomenclature, 4th edition. London: The International Trust for Zoological Nomenclature. Available online at https://web.archive.org/web/20090524144249/http://www.iczn.org/iczn/index.jsp. Accessed September 27, 2009. Zoological nomenclature {{zoology-stub