In biology, a type is that which fixes a name to a taxon. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to Depending on the nomenclature code which is applied to the organism in question, a type may be a specimen, culture, illustration, description or taxon. The Nomenclature Codes (or the " Codes of nomenclature") are the rulebooks that govern biological nomenclature
For example, the Natural History Museum in London has a specimen numbered 1886. The Natural History Museum is one of three large Museums on Exhibition Road, South Kensington, London (the others are the Science Museum 6. 24. 20 of the Spotted Harrier (Circus assimilis), which is the holotype for that species; the name Circus assimilis refers, by definition, to the species of that particular specimen. The Spotted Harrier, Circus assimilis, also known as the Smoke Hawk is a large Bird of prey in the family Accipitridae. A holotype is one of several possible Biological types A type is what fixes a name to a Taxon.
Note that at least for type specimens there is no requirement for a "typical" individual to be used. When describing new species, this is often impossible to tell anyway, until more research has been done. Genera and families, particularly those established by early taxonomists, tend to be named after species that are more "typical" for them, but here too this is not always the case and due to changes in systematics cannot be. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic In Biological classification, family ( Latin Biological systematics is the study of the diversity of Life on the planet Earth both past and present and the relationships among living things through time Hence, the term name-bearing type or onomatophore is sometimes used, to denote the fact that biological types do not define "typical" individuals or (in zoology) taxa, but rather fix a scientific name to a specific operational taxonomic unit. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to Type specimens are theoretically even allowed to be aberrant or deformed individuals or color variations, though this is rarely the case as it makes it hard to determine to which population the individual belonged.
The usage of the term type is somewhat complicated by slightly different uses in botany and zoology. Botany, plant science(s, phytology, or plant biology is a branch of Biology and is the scientific study of plant Life Zoology (from Greek ζῷον, zoon, "animal" + λόγος, " Logos " "knowledge" is the branch of In the PhyloCode, type specimen are replaced by clade delimitations. The International Code of Phylogenetic Nomenclature, known for short as the PhyloCode, is a developing draft for a formal set of rules governing Phylogenetic A clade is a taxonomic group comprising a single Common ancestor and all the descendants of that ancestor
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Types in botany
In botanical nomenclature, a type (typus, nomenclatural type), "is that element to which the name of a taxon is permanently attached. Botanical nomenclature is the formal naming of plants from a scientific point of view "[1]
A botanical name, by itself, is only a phrase (of one to three words). A botanical name is a formal scientific name conforming to the International Code of Botanical Nomenclature (ICBN and if the plant is a Cultigen, the For a name to be meaningful it is necessary to be sure what it applies to. A type fixes a botanical name to a taxon. A taxon (plural taxa) or taxonomic unit, is a name designating an organism or a group of Organisms In Biological nomenclature according to In botany a type is either a specimen or an illustration. A specimen is a real plant (or one or more parts of a plant or a lot of small plants), dead and kept safe, "curated", in a herbarium (or the equivalent for fungi). Notable cases of where an illustration may serve as a type are (this is not an exclusive listing):
- A detailed drawing, painting, etc, depicting the plant, from the early days of plant taxonomy (as we now know it). In those days a dried plant was difficult to transport and hard to keep safe for the future: many specimens that famous botanists looked at have since been lost or damaged. However, there were devoted botanical artists who upon assignment by a botanist (or naturalist) could make a faithful and detailed work of botanical art, for inclusion in a costly book.
- A detailed picture of something that can be seen only through a microscope. A tiny 'plant' on a microscope slide makes for a poor type: the microscope slide may be lost or damaged, or it may be very difficult to find the 'plant' in question among whatever else is on the microscope slide. An illustration makes for a much more reliable type (Art 37. 5 of the Vienna Code, 2006).
Note that a type only fixes a name to a single representative of the taxon. A type does not determine the circumscription of the taxon. For example, the common dandelion is a controversial taxon: some botanists consider it to consist of over a hundred species, although most botanists regard it to be a single species. The type of the name Taraxacum officinale is the same whether the circumscription of the species includes all those small species (Taraxacum officinale is a 'big' species) or whether the circumscription is limited to only one small species among the other hundred (Taraxacum officinale is a 'small' species). In this case the name Taraxacum officinale is the same and the type of the name is the same, but the extent of what the name actually applies to varies strongly. Setting the circumscription of a taxon is done by a taxonomist in a publication.
Miscellaneous notes:
- Usually, only a species or an infraspecific taxon can have a type of its own. In Botanical nomenclature, an infraspecific taxon is a taxon at a rank below that of species (i For a new taxon (published on or after 1 January 1958) at these ranks a type should not be an illustration.
- A genus (almost always) has the same type as that of one of its species. For convenience this species may, unofficially, be called its type species, a phrase that has no standing under the ICBN. In Taxonomy, a type species is the species that originally defined a genus. The International Code of Botanical Nomenclature ( ICBN) is the set of rules and recommendations dealing with the formal Botanical names that are given to Only by conservation may a genus have its own type. A conserved name or nomen conservandum (plural nomina conservanda) is a scientific name that enjoys special nomenclatural protection
- A family has the same type as that of one of its genera (that is, almost always the type of a species). For convenience this genus may, unofficially, be called its type genus, a phrase that has no standing under the ICBN. In biology the phrase type genus is used differently depending on the nomenclatural ''Code'' that applies In zoological nomenclature, a type
- The ICBN provides a listing of the various kinds of type in Art 9, the most important of which is the holotype. A holotype is one of several possible Biological types A type is what fixes a name to a Taxon. Note that the word "type" appears in botanical literature as a part of several terms that have no status under the ICBN: for example a clonotype, an herbarium specimen vegetatively propagated from (and thus a clone of) the same plant from which a type specimen was made that is used for documenting the type collection. In Botany, a Herbarium is a collection of preserved Plant specimens Cloning in Biology is the process of producing populations of genetically-identical individuals that occurs in nature when organisms such as Bacteria, Insects
Types in zoology
In zoological nomenclature, a type is a specimen or a taxon. "ICZN" redirects here It is also sometimes used for the International Code of Zoological Nomenclature in error A "name-bearing type" "provides the objective standard of reference whereby the application of the name of a nominal taxon can be determined. "
Definitions
- A type specimen is a vernacular term (not a formally defined term) typically used for an individual or fossil that is any of the various name-bearing types for a species. In Biology, a species is one of the basic units of Biological classification and a Taxonomic rank. For example, the type specimen for the species Homo neanderthalensis was the specimen "Neanderthal-1" discovered by Johann Karl Fuhlrott in 1856 at Feldhofer in the Neander Valley in Germany, consisting of a skullcap, thigh bones, part of a pelvis, some ribs, and some arm and shoulder bones. The Neanderthal (neɪˈændərtɑːl also with /niː-/ and /-θɔːl/ or Neandertal, is an extinct member of the Homo genus that is known from Johann Carl Fuhlrott was born December 31 1803 in Leinefelde, Germany, and died October 17 1877 in Elberfeld There may be more than one type specimen, but there is (at least in modern times) only one holotype. A holotype is one of several possible Biological types A type is what fixes a name to a Taxon.
- A type species is the nominal species that is the name-bearing type of a nominal genus or subgenus. A genus (plural genera from Γένος Latin genus "descent family type gender" is a low-level Taxonomic In Biology, a subgenus is a Taxonomic rank directly below Genus.
- A type genus is the nominal genus that is the name-bearing type of a nominal family-group taxon.
- The type series are all those specimens included by the author in a taxon's formal description, unless the author explicitly or implicitly excludes them as part of the series.
Use of types
Although in reality biologists may examine many specimens (when available) of a new taxon before writing an official published species description, nonetheless, under the formal rules for naming species (the International Code of Zoological Nomenclature), a single type must be designated, as part of the published description. The International Code of Zoological Nomenclature is a set of rules in Zoology that have one fundamental aim to provide the maximum universality and continuity in the naming
When a single specimen is clearly designated in the original description, this specimen is known as the holotype of that species. A holotype is one of several possible Biological types A type is what fixes a name to a Taxon. The holotype needs to be placed in a major museum, or similar well-known public collection, so that it is freely available for later examination by other biologists.
Included in the type description should be a discussion of similarities to and differences from closely related species, and an indication of where the type specimen or specimens are deposited for examination. The geographical location where a type specimen was originally found is known as its type locality.
Zoological collections are maintained by universities and museums. Ensuring that types are kept in good condition and made available for examination by taxonomists are two important functions of such collections. And, while there is only one holotype designated, there can be other "type" specimens, the following of which are formally defined:
- Paratype – Any additional specimen listed in the type series, where the original description designated a holotype. Zoology In Zoological nomenclature, a paratype is officially defined as a "Each specimen of a type series other than the Holotype " In turn These are not name-bearing types.
- Neotype – A specimen later selected to serve as the single type specimen when an original holotype has been lost or destroyed, or where the original author never cited a specimen.
- Syntype – Any of two or more specimens listed in a species description where a holotype was not designated; historically, syntypes were often explicitly designated as such, and under the present Code this is a requirement, but modern attempts to publish species description based on syntypes are generally frowned upon by practicing taxonomists, and most are gradually being replaced by lectotypes. In zoological nomenclature, a syntype is any of two or more specimens listed in a species description where a Holotype was not designated a practice which was common The International Code of Zoological Nomenclature is a set of rules in Zoology that have one fundamental aim to provide the maximum universality and continuity in the naming In zoological nomenclature, a syntype is any of two or more specimens listed in a species description where a Holotype was not designated a practice which was common Those which still exist are still considered name-bearing types.
- Lectotype – A specimen later selected to serve as the single type specimen for species originally described from a set of syntypes. In zoological nomenclature, a syntype is any of two or more specimens listed in a species description where a Holotype was not designated a practice which was common
- Paralectotype – Any additional specimen from among a set of syntypes, after a lectotype has been designated from among them. In zoological nomenclature, a syntype is any of two or more specimens listed in a species description where a Holotype was not designated a practice which was common These are not name-bearing types.
- Hapantotype – A special case in Protistans where the type consists of two or more specimens of "directly related individuals representing distinct stages in the life cycle"; these are collectively treated as a single entity, and lectotypes cannot be designated from among them. Protists (ˈproʊtɨst are a diverse group of eukaryotic Microorganisms Historically protists were treated as the kingdom Protista but this In zoological nomenclature, a syntype is any of two or more specimens listed in a species description where a Holotype was not designated a practice which was common
The various types listed above are necessary because many species were described one or two centuries ago, when a single type specimen, a holotype, was often not designated. Also, types were not always carefully preserved, and intervening events such as wars and fires have resulted in destruction of original type material. The validity of a species name often rests upon the availability of original type specimens; or, if the type cannot be found, or one has never existed, upon the clarity of the description.
The ICZN has only existed since 1961 when the first edition of the Code was published. "ICZN" redirects here It is also sometimes used for the International Code of Zoological Nomenclature in error The International Code of Zoological Nomenclature is a set of rules in Zoology that have one fundamental aim to provide the maximum universality and continuity in the naming The ICZN does not always demand a type specimen for the historical validity of a species, and many "type-less" species do exist, perhaps the most notable being Homo sapiens. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus This example is instructive: the current edition of the Code, Article 75. The International Code of Zoological Nomenclature is a set of rules in Zoology that have one fundamental aim to provide the maximum universality and continuity in the naming 3, prohibits the designation of a neotype unless there is "an exceptional need" for "clarifying the taxonomic status" of a species; as the status and identity of H. In biology a type is that which fixes a name to a Taxon. Depending on the nomenclature code which is applied to the organism in question a type may be a specimen sapiens is not questioned, there is no exceptional need for clarification, and "any such neotype designation is invalid" (Article 75. 2).
Recently some species have been described where the type specimen was released alive back into the wild, such as the Bulo Burti Bush-shrike (Laniarius liberatus), in which the species description included DNA sequences from blood and feather samples. The Bulo Burti Boubou ( Laniarius liberatus) is a medium-sized Passerine Bird in the Bushshrike family Assuming there is no future question as to the status of such a species, the absence of a type specimen does not invalidate the name, but it may be necessary in the future to designate a neotype for such a taxon, should any questions arise.
There are many other permutations and variations on terms using the suffix "-type" (e. g. , allotype, cotype, topotype, generitype, isoneotype, etc. ) but these are not formally regulated by the Code, and a great many are obsolete and/or idiosyncratic.
The term fixation is used by the Code for the declaration of a name-bearing type, whether by original or subsequent designation.
Type species
Each genus must have a designated type species (the term "genotype" was once used for this but has been abandoned because the word has been co-opted for use in genetics, and is much better known in that context). Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is The description of a genus is usually based primarily on its type species, modified and expanded by the features of other included species. The generic name is permanently associated with the name-bearing type of its type species.
Ideally, a type species best exemplifies the essential characteristics of the genus to which it belongs, but this is subjective and, ultimately, technically irrelevant, as it is not a requirement of the Code. If the type species proves, upon closer examination, to belong to a pre-existing genus (a common occurrence), then all of the constituent species must be either moved into the pre-existing genus, or disassociated from the original type species and given a new generic name; the old generic name passes into synonymy, and is abandoned, unless there is a pressing need to make an exception (decided case-by-case, via petition to the International Commission on Zoological Nomenclature). "ICZN" redirects here It is also sometimes used for the International Code of Zoological Nomenclature in error
Type genus
A type genus is that genus from which the name of a family or subfamily is formed. As with type species, the type genus is not necessarily the most representative, but is usually the earliest described, largest or best known genus. It is not uncommon for the name of a family to be based upon the name of a type genus which has passed into synonymy; the family name does not need to be changed in such a situation.
See also
External links
- ICZN: International Code of Zoological Nomenclature, the official website
- Fishbase Glossary section. The phrase nomen nudum is a Latin term meaning "naked name" In zoological nomenclature, a nomen dubium ( Latin for "doubtful name" plural nomina dubia) is a scientific name that is
References
- ^ Art 7. 1 International Code of Botanical Nomenclature. The International Code of Botanical Nomenclature ( ICBN) is the set of rules and recommendations dealing with the formal Botanical names that are given to
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