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In
taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only about biological ...
, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

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, name or a scientific name; more informally it is also called a Latin name. The first part of the name – the '' generic name'' – identifies the
genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying gr ...
to which the species belongs, while the second part – the specific name or specific epithet – identifies the species within the genus. For example, modern humans belong to the genus ''
Homo ''Homo'' () is the that emerged in the (otherwise extinct) genus ' that encompasses the extant species ' (), plus several extinct species classified as either to or closely related to modern humans (depending on the species), most notably ' ...

Homo
'' and within this genus to the species ''
Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread of , characterized by and large, complex brains. This has enabled the development of advanced , , and . Humans are highly social and tend to live in complex s composed of many ...

Homo sapiens
''. ''
Tyrannosaurus rex ''Tyrannosaurus'' is a genus of large theropoda, theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosau ...

Tyrannosaurus rex
'' is probably the most widely known binomial. The ''formal'' introduction of this system of naming species is credited to
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

Carl Linnaeus
, effectively beginning with his work ''
Species Plantarum ' (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, i ...
'' in 1753. But as early as 1622,
Gaspard Bauhin Gaspard Bauhin or Caspar Bauhin ( la, Casparus Bauhinus; 17 January 1560 – 5 December 1624), was a Swiss Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places *Swiss, Missouri *Swiss, North Carolina *Swiss, West Virgini ...

Gaspard Bauhin
introduced in his book ''Pinax theatri botanici'' (English, ''Illustrated exposition of plants'') many names of genera that were later adopted by 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 The International Code of Zoological Nomenclature (ICZN) is a widely accepted in that rules the formal of treated as s. It is also informally known as the ICZN Code, for its publisher, the (which shares the acronym "ICZN"). The rules princi ...
'' (''ICZN'') for animals and the ''
International Code of Nomenclature for algae, fungi, and plants The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical name A botanical name is a formal scientific name Science (from the Latin Latin (, ...
'' (''ICNafp''). Although the general principles underlying binomial nomenclature are common to these two codes, there are some differences, both in terminology they use and in their particular rules. In modern usage, the first letter of the generic name is always capitalized in writing, while that of the specific epithet is not, even when derived from a
proper noun A proper noun is a noun A noun () is a word In linguistics, a word of a spoken language can be defined as the smallest sequence of phonemes that can be uttered in isolation with semantic, objective or pragmatics, practical meaning (lingu ...
such as the name of a person or place. Similarly, both parts are italicized in normal text (or underlined in handwriting). Thus the binomial name of the annual phlox (named after botanist
Thomas Drummond Captain Thomas Drummond (10 October 1797 – 15 April 1840), from Edinburgh Edinburgh (; sco, Edinburgh; gd, Dùn Èideann ) is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. Historically part of ...
) is now written as ''
Phlox drummondii ''Phlox drummondii'' (commonly annual phlox or Drummond's phlox) is a flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orde ...

Phlox drummondii
''. Often, after a species name is introduced in a text, the generic name is abbreviated to the first letter in subsequent mentions (e. g., ''P. drummondii''). In scientific works, the
authority In the fields of sociology Sociology is the study of society, human social behaviour, patterns of social relationships, social interaction, and culture that surrounds everyday life. It is a social science that uses various methods of Empiric ...

authority
for a binomial name is usually given, at least when it is first mentioned, and the year of publication may be specified. *In
zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical stru ...
** "''
Patella vulgata ''Patella vulgata'', common name the common limpet or common European limpet is a species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodive ...

Patella vulgata
'' Linnaeus, 1758". The name "Linnaeus" tells the reader who published the name and description for this species of limpet; 1758 is the year the name and original description was published (in this case, in the 10th edition of the book ''
Systema Naturae ' (originally in Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic ...
''). **"''
Passer domesticus The house sparrow (''Passer domesticus'') and also known as the common bird or the common sparrow is a bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves , characterised by feathers, toothless ...

Passer domesticus
'' (Linnaeus, 1758)". The original name given by Linnaeus was ''Fringilla domestica''; the parentheses indicate that the species is now placed in a different genus. The ICZN does not require that the name of the person who changed the genus be given, nor the date on which the change was made, although nomenclatorial catalogs usually include such information. *In
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

botany
**"''
Amaranthus retroflexus ''Amaranthus retroflexus'' is a species of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), f ...
'' L." – "L." is the standard abbreviation used for "Linnaeus". **"''
Hyacinthoides italica ''Hyacinthoides italica'', the Italian bluebell or Italian squill, is a spring-flowering bulbous perennial plant belonging to the family Asparagaceae Asparagaceae is a Family (biology), family of flowering plants, placed in the Order (biology) ...

Hyacinthoides italica
'' (L.) Rothm." – Linnaeus first named this bluebell species ''Scilla italica''; Rothmaler transferred it to the genus ''Hyacinthoides''; the ''ICNafp'' does not require that the dates of either publication be specified.


Origin

The name is composed of two word-forming elements: (
Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an appa ...

Latin
prefix meaning 'two') and ''nomial (literally 'name'). In Medieval Latin, the related word was used to signify one term in a binomial expression in mathematics. The word nomen (plural nomina) means 'name' in Latin.


History

Prior to the adoption of the modern binomial system of naming species, a scientific name consisted of a generic name combined with a specific name that was from one to several words long. Together they formed a system of polynomial nomenclature. These names had two separate functions. First, to designate or label the species, and second, to be a diagnosis or description; however these two goals were eventually found to be incompatible. In a simple genus, containing only two species, it was easy to tell them apart with a one-word genus and a one-word specific name; but as more species were discovered, the names necessarily became longer and unwieldy, for instance, ''Plantago foliis ovato-lanceolatus pubescentibus, spica cylindrica, scapo tereti'' ("plantain with pubescent ovate-lanceolate leaves, a cylindric spike and a
terete Terete is a term in botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" co ...
scape"), which we know today as ''
Plantago media ''Plantago media'', known as the hoary plantain, is a species of flowering plant Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT ...

Plantago media
''. Such "polynomial names" may sometimes look like binomials, but are significantly different. For example, Gerard's herbal (as amended by Johnson) describes various kinds of spiderwort: "The first is called ''Phalangium ramosum'', Branched Spiderwort; the second, ''Phalangium non ramosum'', Unbranched Spiderwort. The other ... is aptly termed ''Phalangium Ephemerum Virginianum'', Soon-Fading Spiderwort of Virginia". The Latin phrases are short descriptions, rather than identifying labels. The
Bauhin Bauhin — a family of physician A physician (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to t ...
s, in particular
Caspar Bauhin Gaspard Bauhin or Caspar Bauhin ( la, Casparus Bauhinus; 17 January 1560 – 5 December 1624), was a Swiss Swiss may refer to: * the adjectival form of Switzerland *Swiss people Places *Swiss, Missouri *Swiss, North Carolina *Swiss, West Virgini ...

Caspar Bauhin
(1560–1624), took some important steps towards the binomial system, by pruning the Latin descriptions, in many cases to two words., p. v The adoption by biologists of a system of strictly binomial nomenclature is due to
Swedish Swedish or ' may refer to: * Anything from or related to Sweden, a country in Northern Europe * Swedish language, a North Germanic language spoken primarily in Sweden and Finland * Swedish alphabet, the official alphabet used by the Swedish langua ...

Swedish
botanist and physician
Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

Carl Linnaeus
(1707–1778). It was in Linnaeus's 1753 ''
Species Plantarum ' (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, i ...
'' that he began consistently using a one-word "trivial name" () after a generic name (genus name) in a system of binomial nomenclature. Trivial names had already appeared in his '' Critica Botanica'' (1737) and '' Philosophia Botanica'' (1751). This trivial name is what is now known as a
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species In biology, a species is the basic unit of biological classi ...
(''ICNafp'') or
specific nameSpecific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In Taxonomy (biology), taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), ...
(''ICZN''). The Bauhins' genus names were retained in many of these, but the descriptive part was reduced to a single word. Linnaeus's trivial names introduced an important new idea, namely that the function of a name could simply be to give a species a unique label. This meant that the name no longer need be descriptive; for example both parts could be derived from the names of people. Thus Gerard's ''Phalangium ephemerum virginianum'' became ''
Tradescantia virginiana ''Tradescantia virginiana'', the Virginia spiderwort, is the type species Type may refer to: Science and technology Computing * Typing Typing is the process of writing or inputting text by pressing keys on a typewriter, computer keyboard, cell ...
'', where the genus name honoured
John Tradescant the Younger John Tradescant the Younger (; 4 August 1608 – 22 April 1662), son of John Tradescant the Elder, was a botanist and gardener. The standard author abbreviation Trad. is applied to species he described. Biography Son of John Tradescant the ...

John Tradescant the Younger
, an English botanist and gardener. A bird in the parrot family was named '''', meaning "Alexander's parrot", after
Alexander the Great Alexander III of Macedon ( grc-gre, Αλέξανδρος}, ; 20/21 July 356 BC – 10/11 June 323 BC), commonly known as Alexander the Great, was a king (''basileus ''Basileus'' ( el, βασιλεύς) is a Greek term and title A title ...

Alexander the Great
, whose armies introduced eastern parakeets to Greece. Linnaeus's trivial names were much easier to remember and use than the parallel polynomial names and eventually replaced them.


Value

The value of the binomial nomenclature system derives primarily from its economy, its widespread use, and the uniqueness and stability of names that the Codes of
Zoological Zoology ()The pronunciation of zoology as is typically regarded as nonstandard, though it is not uncommon. is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical s ...
and
Botanical Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes knowledge in th ...
,
Bacterial Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology, an ...
and Viral Nomenclature provide: * Economy. Compared to the polynomial system which it replaced, a binomial name is shorter and easier to remember. It corresponds to the widespread system of
family name In some cultures, a surname, family name, or last name is the portion of one's personal name A personal name, or full name, in onomastic Onomastics or onomatology is the study of the etymology, history, and use of proper names. An ''wikt ...
plus
given name A given name (also known as a first name or forename) is the part of a personal name A personal name, or full name, in onomastic Onomastics or onomatology is the study of the etymology, history, and use of proper names. An ''wikt:ortho ...
(s) used to name people in many cultures. * Widespread use. The binomial system of nomenclature is governed by international codes and is used by biologists worldwide. A few binomials have also entered common speech, such as ''Homo sapiens'', ''E. coli'', ''Boa constrictor'', and ''Tyrannosaurus rex''. * Uniqueness. Provided that taxonomists agree as to the limits of a species, it can have only one name that is correct under the appropriate
nomenclature code Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classifica ...
, generally the earliest published if two or more names are accidentally assigned to a species. However, establishing that two names actually refer to the same species and then determining which has priority can be difficult, particularly if the species was named by biologists from different countries. Therefore, a species may have more than one regularly used name; all but one of these names are "
synonyms A synonym is a word, morpheme A morpheme is the smallest meaningful lexical item in a language. A morpheme is not a word. The difference between a morpheme and a word is that a morpheme bound and free morphemes, sometimes does not stand alone ...
". Furthermore, within zoology or botany, each species name applies to only one species. If a name is used more than once, it is called a
homonym In linguistics, homonyms, broadly defined, are words which are homographs (words that share the same spelling, regardless of pronunciation) or homophones (words that share the same pronunciation, regardless of spelling), or both. For example, acco ...
. * Stability. Although stability is far from absolute, the procedures associated with establishing binomial names, such as the principle of priority, tend to favor stability. For example, when species are transferred between genera (as not uncommonly happens as a result of new knowledge), the second part of the binomial is kept the same (unless it becomes a homonym). Thus there is disagreement among botanists as to whether the genera '' Chionodoxa'' and ''
Scilla ''Scilla'' () is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including thei ...

Scilla
'' are sufficiently different for them to be kept separate. Those who keep them separate give the plant commonly grown in gardens in Europe the name ''
Chionodoxa siehei ''Scilla forbesii'', known as Forbes' glory-of-the-snow, is a bulbous perennial plant from west Turkey flowering in early spring. It is considered synonymous with ''Scilla siehei'', known as Siehe's glory-of-the-snow, by some sources, although ...
''; those who do not give it the name ''Scilla siehei''. The ''siehei'' element is constant. Similarly if what were previously thought to be two distinct species are demoted to a lower rank, such as subspecies, the second part of the binomial name is retained as a trinomen (the third part of the new name). Thus the Tenerife robin may be treated as a different species from the European robin, in which case its name is ''Erithacus superbus'', or as only a subspecies, in which case its name is ''Erithacus rubecula superbus''. The ''superbus'' element of the name is constant, as is its authorship and year of publication.


Problems

Binomial nomenclature for species has the effect that when a species is moved from one genus to another, sometimes the specific name or epithet must be changed as well. This may happen because the specific name is already used in the new genus, or to agree in gender with the new genus if the specific epithet is an adjective modifying the genus name. Some biologists have argued for the combination of the genus name and specific epithet into a single unambiguous name, or for the use of uninomials (as used in nomenclature of ranks above species). Because genus names are unique only within a nomenclature code, it is possible for two or more species to share the same genus name and even the same binomial if they occur in different kingdoms. At least 1240 instances of genus name duplication occur (mainly between zoology and botany).


Relationship to classification and taxonomy

Nomenclature (including binomial nomenclature) is not the same as classification, although the two are related. Classification is the ordering of items into groups based on similarities or differences; in
biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...
, species are one of the kinds of item to be classified. In principle, the names given to species could be completely independent of their classification. This is not the case for binomial names, since the first part of a binomial is the name of the genus into which the species is placed. Above the rank of genus, binomial nomenclature and classification are partly independent; for example, a species retains its binomial name if it is moved from one family to another or from one order to another, unless it better fits a different genus in the same or different family, or it is split from its old genus and placed in a newly created genus. The independence is only partial since the names of families and other higher taxa are usually based on genera.
Taxonomy Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also refer to a specific classification scheme. Originally used only about biological ...
includes both nomenclature and classification. Its first stages (sometimes called "
alpha taxonomy In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxon, taxa (singular: ...
") are concerned with finding, describing and naming species of living or
fossil A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication used by humans, inc ...

fossil
organisms. Binomial nomenclature is thus an important part of taxonomy as it is the system by which species are named. Taxonomists are also concerned with classification, including its principles, procedures and rules.


Derivation of binomial 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 a number of sources, of which Latin is only one. These include: * Latin, either
classical Classical may refer to: European antiquity *Classical antiquity, a period of history from roughly the 7th or 8th century B.C.E. to the 5th century C.E. centered on the Mediterranean Sea *Classical architecture, architecture derived from Greek and ...

classical
or
medieval In the history of Europe The history of Europe concerns itself with the discovery and collection, the study, organization and presentation and the interpretation of past events and affairs of the people of Europe since the beginning of ...
. Thus, both parts of the binomial name ''Homo sapiens'' are Latin words, meaning "wise" (''sapiens'') "human/man" (''Homo''). *
Classical Greek Ancient Greek includes the forms of the Greek language Greek (modern , romanized: ''Elliniká'', Ancient Greek, ancient , ''Hellēnikḗ'') is an independent branch of the Indo-European languages, Indo-European family of languages, nati ...
. The genus ''
Rhododendron ''Rhododendron'' (from Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as G ...

Rhododendron
'' was named by
Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomi ...

Linnaeus
from the Greek word , itself derived from ''rhodon'', "rose", and ''dendron'', "tree". Greek words are often converted to a Latinized form. Thus coca (the plant from which cocaine is obtained) has the name ''
Erythroxylum coca ''Erythroxylum coca'' is one of two species of cultivated coca Coca is any of the four cultivated plants in the family (biology), family Erythroxylaceae, native to western South America. Coca is known worldwide for its Psychoactive plant, psyc ...

Erythroxylum coca
''. ''Erythroxylum'' is derived from the Greek words ''erythros'', red, and ''xylon'', wood. The Greek neuter ending - (-on) is often converted to the Latin neuter ending -um. * Other languages. The second part of the name ''
Erythroxylum coca ''Erythroxylum coca'' is one of two species of cultivated coca Coca is any of the four cultivated plants in the family (biology), family Erythroxylaceae, native to western South America. Coca is known worldwide for its Psychoactive plant, psyc ...

Erythroxylum coca
'' is derived from ''kuka'', the name of the plant in
Aymara Aymara may refer to: Languages and people * Aymaran languages Aymaran (also Jaqi or Aru) is one of the two dominant language families in the central Andes alongside Quechua languages, Quechuan. The family consists of Aymara language, Aymara, wi ...
and
Quechua Quechua may refer to: *Quechua people, several indigenous ethnic groups in South America, especially in Peru *Quechuan languages, a Native South American language family spoken primarily in the Andes, derived from a common ancestral language **Sou ...
. Since many dinosaur fossils were found in Mongolia, their names often use
Mongolian Mongolian may refer to: * Something of, from, or related to Mongolia, a country in Asia * Mongolian people, or Mongols * Mongolia (1911–24), the government of Mongolia, 1911–1919 and 1921–1924 * Mongolian language * Mongolian alphabet * Mongo ...

Mongolian
words, e.g. ''
Tarchia ''Tarchia'' (meaning "brainy one") is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The te ...
'' from ''tarkhi'', meaning "brain", or ''
Saichania ''Saichania'' (Mongolian meaning "beautiful one") is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classif ...

Saichania
'' meaning "beautiful one". * Names of people (often naturalists or biologists). The name '''' commemorates two people:
Pierre Magnol Pierre Magnol (8 June 1638 – 21 May 1715) was a French botanist Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientif ...
, a French botanist, and Archibald Campbell, a doctor in
British India The Provinces of India, earlier Presidencies of British India and still earlier, Presidency towns, were the administrative divisions of British governance in the Indian subcontinent. Collectively, they have been called British India. In one ...

British India
. * Names of places. The lone star tick, ''
Amblyomma americanum ''Amblyomma americanum'', also known as the lone star tick, the northeastern water tick, or the turkey tick, or the ‘’Cricker Tick’’, is a type of tick Ticks (suborder Ixodida) are parasitic arachnids that are part of the superorde ...
'', is widespread in the United States. * Other sources. Some binominal names have been constructed from taxonomic anagrams or other re-orderings of existing names. Thus the name of the genus ''
Muilla The genus ''Muilla'' includes three to four species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as ...
'' is derived by reversing the name ''
Allium ''Allium'' is a genus of monocotyledonous flowering plants that includes hundreds of species, including the cultivated onion, garlic, scallion, shallot, leek, and chives. The Generic name (biology), generic name ''Allium'' is the Latin word for ...

Allium
''. Names may also be derived from
jokes A joke is a display of humour in which words are used within a specific and well-defined narrative structure to make people laughter, laugh and is usually not meant to be taken seriously. It takes the form of a story, usually with dialogue, an ...
or
pun The pun, also known as paronomasia, is a form of word play Word play or wordplay (also: play-on-words) is a literary technique A narrative technique (known for literary fictional narratives as a literary technique, literary device, or fict ...
s. For example, Ratcliffe described a number of species of
rhinoceros beetle Dynastinae or rhinoceros beetles are a subfamily of the scarabaeidae, scarab beetle family (biology), family (Scarabaeidae). Other common names – some for particular groups of rhinoceros beetles – include Hercules beetles, Dynastes t ...

rhinoceros beetle
, including '' Cyclocephala nodanotherwon''. The first part of the name, which identifies the genus, must be a word which can be treated as a Latin
singular Singular may refer to: * Singular, the grammatical number In linguistics, grammatical number is a grammatical category of nouns, pronouns, adjectives, and verb agreement (linguistics), agreement that expresses count distinctions (such as "one", ...
noun in the
nominative case In grammar In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspect of language, as wel ...
. It must be unique within the purview of each nomenclatural code, but can be repeated between them. Thus '' Huia recurvata'' is an extinct species of plant, found as
fossil A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication used by humans, inc ...

fossil
s in
Yunnan Yunnan () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Ku ...

Yunnan
, China, whereas '' Huia masonii'' is a species of frog found in
Java Java ( id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 147.7 million people, Java is the world's List of ...

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 forms: * The second part of a binomial may be an adjective. The adjective must agree with the genus name in
gender Gender is the range of characteristics pertaining to, and differentiating between femininity Femininity (also called womanliness or girlishness) is a set of attributes, behaviors, and roles generally associated with women A woman is ...
. Latin has three genders, masculine, feminine and neuter, shown by varying endings to nouns and adjectives. The
house sparrow The house sparrow (''Passer domesticus'') is a bird Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form ...

house sparrow
has the binomial name ''Passer domesticus''. Here ''domesticus'' ("domestic") simply means "associated with the house". The is ''Nandina domestica'' rather than ''Nandina domesticus'', since ''Nandina'' is feminine whereas ''Passer'' is masculine. The tropical fruit langsat is a product of the plant ''Lansium parasiticum'', since ''Lansium'' is neuter. Some common endings for Latin adjectives in the three genders (masculine, feminine, neuter) are ''-us'', ''-a'', ''-um'' (as in the previous example of ''domesticus''); ''-is'', ''-is'', ''-e'' (e.g. ''tristis'', meaning "sad"); and ''-or'', ''-or'', ''-us'' (e.g. ''minor'', meaning "smaller"). For further information, see Latin declension: Adjectives. * The second part of a binomial may be 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 Apposition is a grammatical construction in which two elements, normally noun phrasesA noun phrase, or nominal (phrase), is a phrase In everyday speech, a phrase is any group of words, often carrying a special idiomatic meaning; in this sense it ...
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. * The second part of a binomial may be a noun in the
genitive In grammar In linguistics Linguistics is the scientific study of language, meaning that it is a comprehensive, systematic, objective, and precise study of language. Linguistics encompasses the analysis of every aspect of language, a ...
(possessive) case. The genitive case is constructed in a number of ways in Latin, depending on the
declension In linguistics, declension is the changing of the form of a word, generally to express its syntactic function in the sentence, by way of some inflection. The inflectional change of verbs is called Grammatical conjugation, conjugation. Declensions ...
of the noun. Common endings for masculine and neuter nouns are ''-ii'' or ''-i'' in the singular and ''-orum'' in the plural, and for feminine nouns ''-ae'' in the singular and ''-arum'' in the plural. The noun may be part of a person's name, often the surname, as in the
Tibetan antelope The Tibetan antelope or chiru (''Pantholops hodgsonii'') (, pronounced ; ) is a medium-sized bovid native to the Tibetan plateau The Tibetan Plateau (), also known in China as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as t ...

Tibetan antelope
(''Pantholops hodgsonii''), the shrub '' Magnolia hodgsonii'', or the (''Anthus hodgsoni''). The meaning is "of the person named", so that ''Magnolia hodgsonii'' means "Hodgson's magnolia". The ''-ii'' or ''-i'' endings show that in each case Hodgson was a man (not the same one); had Hodgson 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 Charles Wallace Richmond (December 31, 1868 – May 19, 1932) was an American ornithologist. He is best remembered for a compilation of the Latin names of birds that is called the Richmond Index. Life and work He was born in Kenosha, Wisconsin and ...
, in honour of Hodgson. Rather than a person, the noun may be related to a place, as with ''
Latimeria chalumnae The West Indian Ocean coelacanth (''Latimeria chalumnae'') (sometimes known as gombessa, African coelacanth, or simply coelacanth) is a crossopterygian, one of two extant species of coelacanth The coelacanths ( ) constitute a now-rare order ...

Latimeria chalumnae
'', meaning "of the
Chalumna River The Chalumna River ( xh, Tyolomnqa) is a river in the Eastern Cape The Eastern Cape ( xh, iMpuma-Kapa; af, Oos-Kaap; st, Kapa Botjhabela) is one of the provinces of South Africa South Africa is divided into nine provinces. On the eve of the 19 ...
". Another use of genitive nouns is in, for example, the name of the bacterium ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative bacteria, Gram-negative, Facultative anaerobic organism, facultative anaer ...

Escherichia coli
'', where ''coli'' means "of the
colon Colon commonly refers to: * Colon (punctuation) (:), a punctuation mark * Major part of large intestine, the final section of the digestive system Colon may also refer to: Places * Colon, Michigan, US * Colon, Nebraska, US * Kowloon, Hong Kong, s ...

colon
". This formation is common in parasites, as in ''
Xenos vesparum Xenos vesparum is a parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, ...

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 the purview of each nomenclatural code, the second part is quite commonly used in two or more genera (as is shown by examples of ''hodgsonii'' above). The full binomial name must be unique within each code.


Codes

From the early 19th 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 Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classifica ...
. The ''
International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted in that rules the formal of treated as s. It is also informally known as the ICZN Code, for its publisher, the (which shares the acronym "ICZN"). The rules princi ...
'' (''ICZN'') governs the naming of animals, the ''
International Code of Nomenclature for algae, fungi, and plants The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN) is the set of rules and recommendations dealing with the formal botanical name A botanical name is a formal scientific name Science (from the Latin Latin (, ...
'' (''ICNafp'') that of plants (including
cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical ...

cyanobacteria
), and the ''
International Code of Nomenclature of BacteriaThe International Code of Nomenclature of Prokaryotes (ICNP) formerly the International Code of Nomenclature of Bacteria (ICNB) or Bacteriological Code (BC) governs the scientific names for Bacteria and Archaea.P. H. A. Sneath, 2003. A short history ...
'' (''ICNB'') that of
bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typ ...

bacteria
(including
Archaea Archaea ( ; singular archaeon ) constitute a domain Domain may refer to: Mathematics *Domain of a function, the set of input values for which the (total) function is defined **Domain of definition of a partial function **Natural domain of a pa ...

Archaea
).
Virus A virus is a submicroscopic infectious agent In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecu ...

Virus
names are governed by the ''
International Committee on Taxonomy of Viruses The International Committee on Taxonomy of Viruses (ICTV) authorizes and organizes the Taxonomy (biology), taxonomic classification of and the nomenclatures for viruses. The ICTV has developed a universal taxonomic scheme for viruses, and thus h ...
'' (''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 botany, although it is also used by zoologists. Since 1953, "binominal nomenclature" is the technically correct term in zoology. A binominal name is also called a binomen (plural binomina). * Both codes consider the first part of the two-part name for a species to be the "generic name". In the zoological code (''ICZN''), the second part of the name is a "specific name". In the botanical code (''ICNafp''), it is a "specific epithet". Together, these two parts are referred to as a "species name" or "binomen" in the zoological code; or "species name", "binomial", or "binary combination" in the botanical code. "Species name" is the only term common to the two codes. * The ''ICNafp'', the plant code, does not allow the two parts of a binomial name to be the same (such a name is called a
tautonym A tautonym is a scientific name of a species in which both parts of the name have the same spelling, for example, '' Rattus rattus''. The first part of the name is the name of the genus and the second part is referred to as the ''specific epithet ...
), whereas the ''ICZN'', the animal code, does. Thus the American bison has the binomial ''Bison bison''; a name of this kind would not be allowed for a plant. * The starting points, the time from which these codes are in effect (retroactively), vary from group to group. In
botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek wo ...

botany
the starting point will often be in 1753 (the year Carl Linnaeus first published ''
Species Plantarum ' (Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic, i ...
''). In
zoology Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical stru ...
the starting point is 1758 (1 January 1758 is considered the date of the publication of Linnaeus's ''
Systema Naturae ' (originally in Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the Roman Republic ...
'', 10th Edition, and also Clerck's ''Aranei Svecici'').
Bacteriology Bacteriology is the branch and specialty of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactio ...
started anew, with a starting point on 1 January 1980. Unifying the different codes into a single code, the "''BioCode''", has been suggested, although implementation is not in sight. (There is also a published code for a different system of biotic nomenclature which does not use ranks above species, but instead names
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyly, monophyletic – that is, composed of a common ancestor and all its lineage (evolution), lineal descendants - on a phylogenetic tree. R ...

clade
s. This is called the ''
PhyloCode The ''International Code of Phylogenetic Nomenclature'', known as the ''PhyloCode'' for short, is a formal set of rules governing phylogenetic nomenclature. Its current version is specifically designed to regulate the naming of clades, leaving the g ...
''.)


Differences in handling personal names

As noted above, there are some differences between the codes in the way in which binomials can be formed; for example the ''ICZN'' allows both parts to be the same, while the ''ICNafp'' does not. Another difference is in the way in which personal names are used in forming specific names or epithets. The ''ICNafp'' sets out precise rules by which a personal name is to be converted to a specific epithet. In particular, names ending in a consonant (but not "er") are treated as first being converted into Latin by adding "-ius" (for a man) or "-ia" (for a woman), and then being made genitive (i.e. meaning "of that person or persons"). This produces specific epithets like ''lecardii'' for Lecard (male), ''wilsoniae'' for Wilson (female), and ''brauniarum'' for the Braun sisters. By contrast the ''ICZN'' does not require the intermediate creation of a Latin form of a personal name, allowing the genitive ending to be added directly to the personal name. This explains the difference between the names of the plant ''Magnolia hodgsonii'' and the bird ''Anthus hodgsoni''. Furthermore, the ''ICNafp'' requires names not published in the form required by the code to be corrected to conform to it, whereas the ''ICZN'' is more protective of the form used by the original author.


Writing binomial names

By tradition, the binomial names of species are usually typeset in italics; for example, ''
Homo sapiens Humans (''Homo sapiens'') are the most abundant and widespread of , characterized by and large, complex brains. This has enabled the development of advanced , , and . Humans are highly social and tend to live in complex s composed of many ...

Homo sapiens
''. Generally, the binomial should be printed in a
font style In movable type, metal typesetting, a font is a particular #Characteristics, size, weight and style of a typeface. Each font is a matched set of type, with a piece (a "Sort (typesetting), sort") for each glyph, and a typeface consisting of a rang ...

font style
different from that used in the normal text; for example, "''Several more ''Homo sapiens'' fossils were discovered''." When handwritten, a binomial name should be underlined; for example, Homo sapiens. The first part of the binomial, the genus name, is always written with an initial capital letter. Older sources, particularly botanical works published before the 1950s, use a different convention. If the second part of the name is derived from a proper noun, e.g. the name of a person or place, a capital letter was used. Thus the modern form ''Berberis darwinii'' was written as ''Berberis Darwinii''. A capital was also used when the name is formed by two nouns in apposition, e.g. ''Panthera Leo'' or ''Centaurea Cyanus''. In current usage, the second part is never written with an initial capital. 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 binomial 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 which case the genus is written in full when it is first used, but may then be abbreviated to an initial (and a period/full stop). For example, a list of members of the genus ''Canis'' might be written as "''Canis lupus'', ''C. aureus'', ''C. simensis''". In rare cases, this abbreviated form has spread to more general use; for example, the bacterium ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative bacteria, Gram-negative, Facultative anaerobic organism, facultative anaer ...

Escherichia coli
'' is often referred to as just ''E. coli'', and ''
Tyrannosaurus rex ''Tyrannosaurus'' is a genus of large theropoda, theropod dinosaur. The species ''Tyrannosaurus rex'' (''rex'' meaning "king" in Latin), often called ''T. rex'' or colloquially ''T-Rex'', is one of the best represented theropods. ''Tyrannosau ...

Tyrannosaurus rex
'' is perhaps even better known simply as ''T. rex'', these two both often appearing in this form in popular writing even where the full genus name has not already been given. The abbreviation "sp." is used when the actual specific name cannot or need not be specified. The abbreviation "spp." (plural) indicates "several species". These abbreviations are not italicised (or underlined). For example: "''Canis'' sp." means "an unspecified species of the genus ''
Canis ''Canis'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology Biology is the natural science that studies life and living organisms, including their an ...

Canis
''", while "''Canis'' spp." means "two or more species of the genus ''Canis''". (These abbreviations should not be confused with the abbreviations "ssp." (zoology) or "subsp." (botany), plurals "sspp." or "subspp.", referring to one or more
subspecies In biological classification In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interacti ...
. See
trinomen In 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 a ...
(zoology) and
infraspecific name In botany Botany, also called , plant biology or phytology, is the science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific method, builds and Taxonomy (general), organizes kno ...
.) The abbreviation "
cf. The abbreviation ''cf.'' (short for the la, confer/conferatur, both meaning 'compare') is used in writing to refer the reader to other material to make a comparison with the topic being discussed. Style guides recommend that ''cf.'' be used only ...
" (i.e. ''confer'' in Latin) is used to compare individuals/taxa with known/described species. Conventions for use of the "cf." qualifier vary. In paleontology, it is typically used when the identification is not confirmed. For example, "''Corvus'' cf. ''nasicus''" was used to indicate "a fossil bird similar to the
Cuban crow The Cuban crow (''Corvus nasicus'') is one of four species of Corvus (genus), crow that occur on a few key islands in the Caribbean. It is closely related to the white-necked crow (''C. leucognaphalus'') and Jamaican crow (''C. jamaicensis''), wit ...
but not certainly identified as this species". In molecular systematics papers, "cf." may be used to indicate one or more undescribed species assumed related to a described species. For example, in a paper describing the phylogeny of small benthic freshwater fish called darters, five undescribed putative species (Ozark, Sheltowee, Wildcat, Ihiyo, and Mamequit darters), notable for brightly colored nuptial males with distinctive color patterns, were referred to as "''Etheostoma'' cf. ''spectabile''" because they had been viewed as related to, but distinct from, ''Etheostoma spectabile'' (orangethroat darter). This view was supported in varying degrees by DNA analysis. The somewhat informal use of taxa names with qualifying abbreviations is referred to as
open nomenclature Open nomenclature is a vocabulary of partly informal terms and signs in which a taxonomist In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying groups of biological ...
and it is not subject to strict usage codes. In some contexts the dagger symbol ("†") may be used before or after the binomial name to indicate that the species is extinct.


Authority

In scholarly texts, at least the first or main use of the binomial name is usually followed by the "authority" – a way of designating the scientist(s) who first published the name. The authority is written in slightly different ways in zoology and botany. For names governed by the ''ICZN'' the surname is usually written in full together with the date (normally only the year) of publication. The ''ICZN'' recommends that the "original author and date of a name should be cited at least once in each work dealing with the taxon denoted by that name." For names governed by the ''ICNafp'' the name is generally reduced to a standard abbreviation and the date omitted. The
International Plant Names Index The International Plant Names Index (IPNI) describes itself as "a database In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algor ...
maintains an approved list of botanical author abbreviations. Historically, abbreviations were used in zoology too. When the original name is changed, e.g. the species is moved to a different genus, both codes use parentheses around the original authority; the ''ICNafp'' also requires the person who made the change to be given. In the ''ICNafp'', the original name is then called the
basionym In the scientific name of organisms, basionym or basyonym means the original name on which a new name is based; the author citation of the new name should include the authors of the basionym in parentheses. The term original combination or protonym ...
. Some examples: *(Plant) ''
Amaranthus retroflexus ''Amaranthus retroflexus'' is a species of flowering plant The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of Embryophyte, land plants, with 64 Order(biology), orders, 416 Family (biology), f ...
'' L. – "L." is the standard abbreviation for "Linnaeus"; the absence of parentheses shows that this is his original name. *(Plant) ''
Hyacinthoides italica ''Hyacinthoides italica'', the Italian bluebell or Italian squill, is a spring-flowering bulbous perennial plant belonging to the family Asparagaceae Asparagaceae is a Family (biology), family of flowering plants, placed in the Order (biology) ...

Hyacinthoides italica
'' (L.) Rothm. – Linnaeus first named the Italian bluebell ''Scilla italica''; that is the basionym. Rothmaler later transferred it to the genus ''Hyacinthoides''. *(Animal) ''
Passer domesticus The house sparrow (''Passer domesticus'') and also known as the common bird or the common sparrow is a bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves , characterised by feathers, toothless ...

Passer domesticus
'' (Linnaeus, 1758) – the original name given by Linnaeus was ''Fringilla domestica''; unlike the ''ICNafp'', the ''ICZN'' does not require the name of the person who changed the genus to be given.


Other ranks

Binomial nomenclature, as described here, is a system for naming species. Implicitly it includes a system for naming genera, since the first part of the name of the species is a genus name. In a classification system based on ranks there are also ways of naming ranks above the level of genus and below the level of species. Ranks above genus (e.g., family, order, class) receive one-part names, which are conventionally not written in italics. Thus the house sparrow, ''Passer domesticus'', belongs to the family
Passeridae Old World sparrows are a family of small passerine bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves , characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, h ...
. Family names are normally based on genus names, although the endings used differ between zoology and botany. Ranks below species receive three-part names, conventionally written in italics like the names of species. There are significant differences between the ''ICZN'' and the ''ICNafp''. In zoology, the only rank below species is subspecies and the name is written simply as three parts (a trinomen). Thus one of the subspecies of the is ''Anthus hodgsoni berezowskii''. In botany, there are many ranks below species and although the name itself is written in three parts, a "connecting term" (not part of the name) is needed to show the rank. Thus the American black elder is ''Sambucus nigra'' subsp. ''canadensis''; the white-flowered form of the ivy-leaved cyclamen is ''Cyclamen hederifolium'' f. ''albiflorum''.


See also

* Glossary of scientific naming * Botanical name * Hybrid name (botany) * List of botanists by author abbreviation * List of Latin and Greek words commonly used in systematic names * List of organisms named after famous people * List of zoologists by author abbreviation * Scientific terminology * Species description * Undescribed taxon


Notes


References


Bibliography

* * *


External links


Curiosities of Biological Nomenclature

NCBI Taxonomy Database
* {{authority control Biological nomenclature, *