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In
zoological nomenclature
The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the In ...
, a type species (''species typica'') is the
species
In biology, a species is the basic unit of 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 individuals of the appropriate s ...
name with which the name of a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
or
subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological
type specimen(s).
[ Article 67.1] A similar concept is used for suprageneric groups and called a
type genus
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...
.
In
botanical nomenclature, these terms have no formal standing under the
code of nomenclature, but are sometimes borrowed from zoological nomenclature. In botany, the type of a genus name is a specimen (or, rarely, an illustration) which is also the type of a species name. The species name that has that type can also be referred to as the type of the genus name. Names of genus and family ranks, the various subdivisions of those ranks, and some higher-rank names based on genus names, have such types.
[''International Code of Nomenclature for algae, fungi, and plants'' (ICN)]
articles 7 through 10 (Melbourne Code, 2012)
In
bacteriology Bacteriology is the branch and specialty of biology that studies the morphology, ecology, genetics and biochemistry of bacteria as well as many other aspects related to them. This subdivision of microbiology involves the identification, classificat ...
, a type species is assigned for each genus.
Every named genus or subgenus in zoology, whether or not currently recognized as
valid, is theoretically associated with a type species. In practice, however, there is a backlog of untypified names defined in older publications when it was not required to specify a type.
Use in zoology
A type species is both a concept and a practical system that is used in the
classification and nomenclature (naming) of animals. The "type species" represents the reference species and thus "definition" for a particular genus name. Whenever a taxon containing multiple species must be divided into more than one genus, the type species automatically assigns the name of the original taxon to one of the resulting new taxa, the one that includes the type species.
The term "type species" is regulated in
zoological nomenclature
The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the In ...
by article 42.3 of the ''
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the ...
'', which defines a type species as the
name-bearing type Under the ''International Code of Zoological Nomenclature'' (''Code''), the name-bearing type is the biological type that determines the application of a name. Each animal taxon regulated by the ''Code'' at least potentially has a name-bearing type. ...
of the name of a genus or subgenus (a "
genus-group name"). In the Glossary, type species is defined as
The type species permanently attaches a formal name (the generic name) to a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
by providing just one
species
In biology, a species is the basic unit of 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 individuals of the appropriate s ...
within that genus to which the genus name is permanently linked (i.e. the genus must include that species if it is to bear the name). The species name in turn is fixed, in theory, to a type specimen.
For example, the type species for the
land snail genus ''
Monacha
''Monacha'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the subfamily Trochulininae Lindholm, 1927 of the family Hygromiidae, the hairy snails and their allies. MolluscaBase eds. (2021). MolluscaBase. ...
'' is ''Helix cartusiana'', the name under which the species was first described, known as ''
Monacha cartusiana
''Monacha cartusiana'' is a species of small air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Hygromiidae, the hairy snails and their allies.Helix cartusiana var. depressa Caziot, 1909 (invalid; preoccupied)
Mon ...
'' when placed in the genus ''Monacha''. That genus is currently placed within the family
Hygromiidae
Hygromiidae is a taxonomic family of small to medium-sized air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea. Helicellidae Ihering, 1909
Anatomy
Some snails in genera within this family create ...
. The type genus for that family is the genus ''
Hygromia
''Hygromia'' is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Hygromiidae, the hairy snails and their allies. MolluscaBase eds. (2021). MolluscaBase. Hygromia Risso, 1826. Accessed through: Worl ...
''.
The concept of the type species in zoology was introduced by
Pierre André Latreille
Pierre André Latreille (; 29 November 1762 – 6 February 1833) was a French zoologist, specialising in arthropods. Having trained as a Roman Catholic priest before the French Revolution, Latreille was imprisoned, and only regained his freedom ...
.
Citing
The ''International Code of Zoological Nomenclature'' states that the original name (binomen) of the type species should always be cited. It gives an example in Article 67.1. ''
Astacus marinus
''Homarus gammarus'', known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, ''H. ameri ...
'' was later designated as the type species of the genus ''Homarus'', thus giving it the name ''
Homarus marinus
''Homarus gammarus'', known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, ''H. ameri ...
'' . Even though, as a result of
synonymy
A synonym is a word, morpheme, or phrase that means exactly 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 all ...
, this species was originally named as ''Cancer gammarus'', the type species of ''Homarus'' should always be cited under its original designation as a type species: ''Astacus marinus'' .
[On Wikipedia, both names redirect to '']Homarus gammarus
''Homarus gammarus'', known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, ''H. ameri ...
'' , which discusses the type species.
Although the '' International Code of Nomenclature for algae, fungi, and plants'' does not contain the same explicit statement, examples make it clear that the original name is used, so that the "type species" of a genus name need not have a name within that genus. Thus in Article 10, Ex. 3, the type of the genus name ''Elodes'' is quoted as the type of the species name ''Hypericum aegypticum
''Hypericum aegypticum'' is a species of flowering plant of the St. John's wort family ( Hypericaceae) which is native to the Eastern Mediterranean. It was described by Carl Linnaeus in the second volume of his '' Species Plantarum'' in 1753, w ...
'', not as the type of the species name ''Elodes aegyptica''.[ (''Elodes'' is not now considered distinct from '']Hypericum
''Hypericum'' is a genus of flowering plants in the family Hypericaceae (formerly considered a subfamily of Clusiaceae). The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. Many ''Hy ...
''.)
See also
* Glossary of scientific naming
This is a list of terms and symbols used in scientific names for organisms, and in describing the names. For proper parts of the names themselves, see List of Latin and Greek words commonly used in systematic names. Note that many of the abbrevi ...
* Genetypes
Genetypes is a taxonomic concept proposed in 2010 to describe any genetic sequences from type specimens. This nomenclature integrates molecular systematics and terms used in biological taxonomy. This nomenclature is designed to label, or flag, ge ...
– genetic sequence data from type specimens.
* Holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
* Paratype
In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). O ...
* Principle of Typification
* Type (and type specimen
In biology, a type is a particular wiktionary:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to a ...
)
* Type genus
In biological taxonomy, the type genus is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearing type of a nominal ...
References
{{Authority control
Botanical nomenclature
Taxonomy (biology)
Zoological nomenclature