Type species
Encyclopedia
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification
and nomenclature (naming) of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species
to which the name of a genus
is permanently linked. This is an important concept 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, thus reducing the potential for confusion.
Under both the zoological and botanical nomenclature codes, every named genus or subdivision of a genus, whether or not currently recognized as valid
or correct
, should have a type species. In practice however there is a backlog of untypified names.
A similar concept is used for supregeneric groups, the concept of a type genus
.
, which defines a type species as the name-bearing type
of the name of a genus or subgenus (a "genus-group name") is the "type species". In the Glossary, type species is defined as
The type species permanently attaches a genus to its formal name (its generic name) by providing just one species
within that genus to which the genus 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
is Monacha cartusiana
. That genus is currently placed within the family Hygromiidae
. The type genus for that family is the genus Hygromia
.
The concept of the type species in zoology was introduced by Pierre André Latreille
.
, the type for any given taxonomic name - if it has a type - is technically a specimen
(or illustration). In the case of the name of a genus (or of a subdivision of a genus), its type will usually be the type for a species included within it and can be indicated by the name of this species alone.
In modern nomenclature, the type of a genus (often referred to as the generitype) is systematically that of a published species (although that specific name might be currently regarded as a synonym), and thus only a species name is cited. As a result, despite the provisions of the code, it is not unusual to designate a genus' type without regard as to whether that species itself has a type (be in an holotype, lectotype or neotype). The term "type species", although of no formal standing under the Code (beyond performing an operation a code allows), has thus been borrowed from zoological nomenclature.
Classification
Classification may refer to:* Library classification and classification in general* Taxonomic classification * Biological classification of organisms* Medical classification* Scientific classification...
and nomenclature (naming) of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
to which the name of a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
is permanently linked. This is an important concept whenever a taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
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, thus reducing the potential for confusion.
Under both the zoological and botanical nomenclature codes, every named genus or subdivision of a genus, whether or not currently recognized as valid
Valid name (zoology)
In zoological nomenclature, the valid name of a taxon is the zoological name that is to be used for that taxon following the rules in the International Code of Zoological Nomenclature . In other words: a valid name is the correct zoological name of a taxon.In contrast, an invalid name is a name...
or correct
Correct name (botany)
In botany, the correct name according to the International Code of Botanical Nomenclature is the one and only botanical name that is to be used for a particular taxon, when that taxon has a particular circumscription, position and rank. Determining whether a name is correct is a complex procedure...
, should have a type species. In practice however there is a backlog of untypified names.
A similar concept is used for supregeneric groups, the concept of a type genus
Type genus
In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
.
In zoology
The term "type species" is regulated in zoological nomenclature by article 42.3 of the International Code of Zoological NomenclatureInternational Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
, which defines a type species as the name-bearing type
Name-bearing type
Under the International Code of Zoological Nomenclature , the name-bearing type is the biological type that determines the application of a name. Each taxon regulated by the Code at least potentially has a name-bearing type. The name-bearing type can be either a type genus , type species , or type...
of the name of a genus or subgenus (a "genus-group name") is the "type species". In the Glossary, type species is defined as
- "The nominal species that is the name-bearing type of a nominal genus or subgenus".
The type species permanently attaches a genus to its formal name (its generic name) by providing just one species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
within that genus to which the genus 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
Land snail
A land snail is any of the many species of snail that live on land, as opposed to those that live in salt water and fresh water. Land snails are terrestrial gastropod mollusks that have shells, It is not always an easy matter to say which species are terrestrial, because some are more or less...
genus Monacha
Monacha
Monacha is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Hygromiidae, the hairy snails and their allies.- Distribution :...
is Monacha cartusiana
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.This is the type species of the genus Monacha.- Distribution :...
. That genus is currently placed within the family Hygromiidae
Hygromiidae
Hygromiidae is a taxonomic family of small to medium-sized air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Helicoidea.-Anatomy:...
. The type genus for that family is the genus Hygromia
Hygromia
Hygromia is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Hygromiidae, the hairy snails and their allies.-Species:Species within the genus Hygromia include:* Hygromia cinctella Draparnaud, 1801...
.
The concept of the type species in zoology was introduced by Pierre André Latreille
Pierre André Latreille
Pierre André Latreille 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 after recognising a rare species he found in the prison, Necrobia ruficollis...
.
In botany
In botanical nomenclatureBotanical nomenclature
Botanical nomenclature is the formal, scientific naming of plants. It is related to, but distinct from taxonomy. Plant taxonomy is concerned with grouping and classifying plants; botanical nomenclature then provides names for the results of this process. The starting point for modern botanical...
, the type for any given taxonomic name - if it has a type - is technically a specimen
Herbarium
In botany, a herbarium – sometimes known by the Anglicized term herbar – is a collection of preserved plant specimens. These specimens may be whole plants or plant parts: these will usually be in a dried form, mounted on a sheet, but depending upon the material may also be kept in...
(or illustration). In the case of the name of a genus (or of a subdivision of a genus), its type will usually be the type for a species included within it and can be indicated by the name of this species alone.
In modern nomenclature, the type of a genus (often referred to as the generitype) is systematically that of a published species (although that specific name might be currently regarded as a synonym), and thus only a species name is cited. As a result, despite the provisions of the code, it is not unusual to designate a genus' type without regard as to whether that species itself has a type (be in an holotype, lectotype or neotype). The term "type species", although of no formal standing under the Code (beyond performing an operation a code allows), has thus been borrowed from zoological nomenclature.