Binomial nomenclature (also called binominal nomenclature or 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 although they can be based on words from other languages. Such a name is called a binomial name (which may be shortened to just "binomial") a binomen or a scientific name; more informally it is also called a Latin name. The first part of the name identifies the genus to which the species belongs; the second part identifies the species within the genus. For example humans belong to genus Homo and within this genus to the species Homo sapiens. The introduction of this system of naming species is usually credited to Linnaeus.

The application of binomial nomenclature is now governed by various internationally agreed codes of rules of which the two most important are the International Code of Zoological Nomenclature for animals and the International Code of Botanical Nomenclature for plants. Although the general principles underlying binomial nomenclature are common to these two codes there are some differences both in the terminology they use and in their precise rules.

In modern usage the first letter of the first part of the name the genus is always capitalized while that of the second part is not even when derived from a proper noun such as the name of a person or place; both parts are italicized. Thus the binomial name of the annual phlox is now written as Phlox drummondii.

Biologists when using a name of a species usually also give the authority and date of the species description. Thus zoologists will give the name of a particular sea snail species as: Patella vulgata Linnaeus 1758. The name "Linnaeus" tells the reader who it was that described the species; 1758 is the date of the publication in which the original description can be found in this case the book Systema Naturae. Contents 1 History 2 Value 3 Derivation 4 Codes 4.1 Rules 5 See also 6 References 7 External links History Carolus Linnaeus (17071778) a Swedish botanist invented the modern system of binomial nomenclature.

The adoption by biologists of a system of binomial nomenclature is due to Swedish botanist and physician Carl von Linn also known by his Latinized name Carolus Linnaeus (17071778). Linnaeus attempted to describe the entire known natural world. He chose a convenient short-hand binomial scheme for species using only the genus name and the specific name or specific epithet (the terms now used in zoology and botany respectively). Together these form the whole name of the species. Linnaeus attempted to give every species (mineral plant or animal) a two-part name. This was an improvement over descriptive names that involved a whole descriptive phrase comprising numerous words. However binomial nomenclature in various forms had existed before Linnaeus and was used by the Bauhins who lived nearly two hundred years earlier.citation needed Value

The value of the binomial nomenclature system derives primarily from its economy its widespread use and the stability of names it generally favors: Clarity. It avoids the confusions that can be created when attempting to use common names to refer to a species. Common names often differ even from one part of a country to another part and certainly vary from one country to another. In contrast the scientific name can be used all over the world in all languages avoiding confusion and difficulties of translation. Stability. The procedures associated with establishing binomial nomenclature tend to favor stability. Even though such stability as exists is far from absolute it is still advantageous. For example when species are transferred between genera (as not uncommonly happens as a result of new knowledge) if possible the species descriptor is kept the same. Similarly if what were previously thought to be distinct species are demoted from species to a lower rank former species names may be retained as infraspecific descriptors.

Despite the rules favoring stability and uniqueness in practice a single species may have several scientific names in circulation depending largely on taxonomic point of view (see synonymy). Derivation See also: list of Latin and Greek words commonly used in systematic names

A complete binomial name is always treated grammatically as if it were a phrase in the Latin language (hence the common use of the term "Latin name" for a binomial name). However the two parts of a binomial name can each be derived from one of a number of different sources of which Latin is only one. These include: Latin either classical or mediaeval. Thus both parts of the binomial name Homo sapiens are Latin words meaning "wise" (sapiens) "man" (Homo). Classical Greek. The genus Rhododendron was named by Linnaeus from the Greek word itself derived from rhodos rose and dendron tree.1 Greek words are often converted to a Latinized form. Thus coca (the plant from which cocaine is obtained) has the name Erythroxylum coca. Erythroxylum is derived from the Greek words erythros red and xylon wood.2 The Greek neuter ending - (-on) is converted to the Latin neuter ending -um. Other languages. The second part of the name Erythroxylum coca is derived from the name of the plant in the Quechua language. Names of people (often naturalists or biologists). The name Magnolia campbellii commemorates two people: Pierre Magnol a French botanist and Archibald Campbell a doctor in British India.3 Names of places. The lone star tick Amblyomma americanum is widespread in the United States.4 Other sources. Some binominal names have been constructed from anagrams or other re-orderings of existing names. Thus the name of the genus Muilla is derived by reversing the name Allium.5 Names may also be derived from jokes or puns. For example Ratcliffe described a number of species of Rhinoceros beetle including Cyclocephala nodanotherwon.6

The first part of the name which identifies the genus must be a word which can be treated as a Latin singular noun in the nominative case. It must be unique within each kingdom but can be repeated between kingdoms. Thus Huia recurvata is an extinct species of plant found as fossils in Yunnan China whereas Huia masonii is a species of frog found in Java Indonesia. The second part of the name which identifies the species within the genus is also treated grammatically as a Latin word. It can have one of a number of different forms including: An adjective. The adjective modifies the genus name and must agree with it in gender. The house sparrow has the binomial name Passer domesticus. Here domesticus ("domestic") simply means "associated with the house". The sacred bamboo is Nandina domestica7 rather than Nandina domesticus since Nandina is feminine whereas Passer is masculine. The tropical fruit langsat is a product of the plant Lansium domesticum since Lansium is neuter. A noun in the nominative case. An example is the binomial name of the lion which is Panthera leo. Grammatically the noun is said to be in apposition to the genus name and the two nouns do not have to agree in gender; in this case Panthera is feminine and leo is masculine. A noun in the genitive (possessive) case. The genitive case is constructed in a number of different ways in Latin depending on the declension of the noun. Common endings are -i or -ii in the singular and -orum in the plural for masculine and neuter nouns and -ae in the singular and -arum in the plural for feminine nouns. The noun may be part of a person's name often the surname as in the Tibetan antelope Pantholops hodgsonii the shrub Magnolia hodgsonii or the Olive-backed Pipit Anthus hodgsoni. The meaning is "of the person named" so that Magnolia hodgsonii means "Hodgson's magnolia". The -ii (or -i) endings show that Hodgson was a man; had he been a woman hodgsonae would have been used. The person commemorated in the binomial name is not usually (if ever) the person who created the name; for example Anthus hodgsoni was named by Charles Wallace Richmond in honour of Hodgson. Rather than a person the noun may be related to a place as with Latimeria chalumnae meaning "of the Chalumna River". A different example of a genitive noun used as the second part of a binomial name is the name of the bacterium Escherichia coli where coli means "of the colon". This formation is common in parasites as in Xenos vesparum where vesparum means "of the wasps" since Xenos vesparum is a parasite of wasps. Whereas the first part of a binomial name must be unique within a kingdom the second part is quite commonly used in two or more different genera (as is shown by examples of hodgsonii above). The full binomial name must be unique within a kingdom. Codes From the mid nineteenth century onwards it became ever more apparent that a body of rules was necessary to govern scientific names. In the course of time these became nomenclature codes. The International Code of Zoological Nomenclature (ICZN) governs the naming of animals the International Code of Botanical Nomenclature (ICBN) that of plants (including fungi and cyanobacteria) and the International Code of Nomenclature of Bacteria (ICNB)that of bacteria (including Archaea). Virus names are governed by the International Committee on Taxonomy of Viruses (ICTV) a taxonomic code which determines taxa as well as names. These codes differ in certain ways e.g.: "Binomial nomenclature" is the correct term for botany8 although it is also used by zoologists.9 Since 1953 "binominal nomenclature" is the technically correct term in zoology.10 Both codes agree in calling the first part of the two-part name for a species the "genus name". However in zoological nomenclature the second part is called the "species name" whereas in botanical nomenclature the second part is called the "species epithet" and the term "species name" should only be used for the whole name i.e. the combination of the two parts. The ICBN the plant Code does not allow tautonyms whereas the ICZN the animal Code does. The starting points the time from which these codes are in effect (retroactively) vary from group to group. In botany the starting point will often be in 1753 (the year Carl Linnaeus first published Species Plantarum). In zoology the starting point is 1758 (1 January 1758 is considered the date of the publication of Linnaeus's Systema Naturae 10th Edition and also Clerck's Aranei Svecici). Bacteriology started anew with a starting point on 1 January 1980.11 A BioCode has been suggested to replace several codes although implementation is not in sight. There is also a code in development for naming clades called the PhyloCode. Rules Although the fine detail differs there are certain aspects which are universally adopted: As the words "binomial" "binominal" and "binary" all signify the scientific name of each species is formed by the combination of two words: the genus name (also called the generic name). a second word identifying the species within that genus for which the technical term varies as follows: a general term for the word identifying the species is the specific descriptor in zoology the word identifying the species is called the specific name in botany the word identifying the species is called the specific epithet Species names are usually typeset in italics; for example Homo sapiens. Generally the binomial should be printed in a font different from that used in the normal text; for example "Several more Homo sapiens were discovered." When handwritten they should be underlined; for example Homo sapiens. Each name should be underlined individually. The genus name is always written with an initial capital letter. In current usage the species name is never written with an initial capital.1213 For example the entire tiger species is Panthera tigris Some older works on the other hand wrote some specific names (epithets) with an initial capital principally those derived from proper nouns e.g. Berberis Darwinii14 There are several terms for this two-part species name; these include binomen (plural binomina) binomial <name> binominal <name> and species name. All taxa at ranks above species have a name composed of one word only a "uninominal name". The first level subdivisions within a species termed subspecies are each given a name with three parts: these are the two forming the species name plus a third part (the subspecific name) which identifies the subspecies within the species. This is called trinomial nomenclature and is written differently in zoology and botany.15 For example: Two of the subspecies of Olive-backed Pipit are Anthus hodgsoni berezowskii and Anthus hodgsoni hodgsoni The Bengal tiger is Panthera tigris tigris and the Siberian tiger Panthera tigris altaica The tree European Elder is Sambucus nigra subsp. nigra and the American Black Elder is Sambucus nigra subsp. canadensis In scholarly texts the main entry for the binomial is followed by the abbreviated (in botany) or full (in zoology) surname of the scientific authority the scientist who first published the classification. If in the original description the species was assigned to a different genus from that to which it is assigned today the abbreviation or name of the describer and the description date are set in parentheses. For example: (plant) Amaranthus retroflexus L. and (animal) Passer domesticus (Linnaeus 1758) the latter was described by Linnaeus as Fringilla domestica. When used with a common name the scientific name often follows in parentheses although this varies with publication. For example: "The house sparrow (Passer domesticus) is decreasing in Europe". The scientific name should generally be written in full. The exception to this is when several species from the same genus are being listed or discussed in the same paper or report or the same species is mentioned repeatedly; in that case the genus is written in full when it is first used but may then be abbreviated to an initial (and period) for successive species names; for example a list of members of the genus Canis might be written: "Canis lupus C. aureus C. simensis". In rare cases this abbreviated form has spread to more general use; for example the bacterium Escherichia coli is often referred to as just E. coli and Tyrannosaurus rex is perhaps even better known simply as T. rex these two both often appearing in this form even where they are not part of any list of species of the same genus. The abbreviation "sp." is used when the actual specific name cannot or need not be specified. The abbreviation "spp." (plural) indicates "several species". These are not italicised (or underlined). For example: "Canis sp." means "an unspecified species of the genus Canis" while "Canis spp." means "two or more species of the genus Canis". Easily confused with the foregoing usage is the abbreviation "ssp." (zoology) or "subsp." (botany) indicating an unspecified subspecies (see also trinomen infraspecific name (botany)). In the same way the plurals of these are "sspp." or "subspp." The abbreviation "cf." is used when the identification is not confirmed. For example "Corvus cf. splendens" indicates "a bird similar to the House Crow but not certainly identified as this species". Mycology uses the same system as in botany. See also Botanical name (in botany) Hybrid name List of botanists by author abbreviation List of zoologists by author abbreviation Species description References Hyam R. & Pankhurst R.J. (1995) Plants and their names : a concise dictionary Oxford: Oxford University Press ISBN 978-0-19-866189-4  p. 428 Hyam & Pankhurst 1995 p. 182 Hyam & Pankhurst 1995 p. 303 Childs James E.; Paddock Christopher D. (2003) "The ascendancy of Amblyomma americanum as a vector of pathogens affecting humans in the United States" Annual Review of Entomology 48 (1): 307337 doi:10.1146/annurev.ento.48.091801.112728 PMID 12414740  Hyam & Pankhurst 1995 p. 329 Isaak Mark Curiosities of Biological Nomenclature: Puns http://www.curioustaxonomy.net/puns/puns.html retrieved 2011-06-11  Hyam & Pankhurst 1995 p. 334 "International Code Of Botanical Nomenclature Online". Ibot.sav.sk. http://ibot.sav.sk/icbn/frameset/0046Ch4Sec2a042.htm. Retrieved 2010-03-28.  Diane Schmidt and George H. Bell Guide to reference and information sources in the zoological sciences Greenwood Publishing Group 2003 ISBN 1563089777 p. 4. "International Commission on Zoological Nomenclature we site". Iczn.org. http://www.iczn.org/iczn/index.jsparticle11&nfvtrue. Retrieved 2010-03-28.  Sneath P. H. A.. "A short history of the Bacteriological Code". http://www.the-icsp.org/misc/Codehistory.htm. Retrieved 2007-10-29.  Heather Silyn-Roberts (2000). Writing for Science and Engineering: Papers Presentation. p. 198. ISBN 0750646365. http://books.google.com/idhVUU7Gq8QskC&lpgPA198&dqspecies%20epithet%20capitalize&pgPA198#vonepage&qspecies%20epithet%20capitalize.  "Recommendation 60F". International Code of Botanical Nomenclature Vienna Code. 2006. pp. 60F.1. http://ibot.sav.sk/icbn/frameset/0065Ch7OaGoNSec1a60.htm#recF.  Charles F. Sturm Timothy A. Pearce ngel Valds (editors) (2006). The Mollusks: A Guide to Their Study Collection and Preservation. p. 147. ISBN 1581129300. http://books.google.com/id-NbmHx93s8gC&lpgPA147&dqspecies%20epithet%20capitalize&pgPA147#vonepage&qchapter%2010.  Frank A. Bisby Plant Names in Botanical Databases Plant Taxonomic Database Standards No. 3 Version 1.00 December 1994 Published for the International Working Group on Taxonomic Databases for Plant Sciences (TDWG) by the Hunt Institute for Botanical Documentation Carnegie Mellon University Pittsburgh External links Curiosities of Biological Nomenclature The Language of Horticulture