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In biology, a type is a particular
specimen Specimen may refer to: Science and technology * Sample (material), a limited quantity of something which is intended to be similar to and represent a larger amount * Biological specimen or biospecimen, an organic specimen held by a biorepository f ...
(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 anchor or centralizes the defining features of that particular taxon. In older usage (pre-1900 in botany), a type was a taxon rather than a specimen. A taxon is a scientifically named grouping of organisms with other like organisms, a
set Set, The Set, SET or SETS may refer to: Science, technology, and mathematics Mathematics *Set (mathematics), a collection of elements *Category of sets, the category whose objects and morphisms are sets and total functions, respectively Electro ...
that includes some organisms and excludes others, based on a detailed published description (for example a
species description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have b ...
) and on the provision of type material, which is usually available to scientists for examination in a major museum research collection, or similar institution.


Type specimen

According to a precise set of rules laid down in 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 I ...
(ICZN) 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 names that are given to plants, fungi and a few other groups of organisms, all those "tra ...
(ICN), the scientific name of every taxon is almost always based on one particular ''specimen'', or in some cases specimens. Types are of great significance to biologists, especially to taxonomists. Types are usually physical specimens that are kept in a museum or herbarium research collection, but failing that, an image of an individual of that taxon has sometimes been designated as a type. Describing species and appointing type specimens is part of
scientific nomenclature Nomenclature (, ) is a system of names or terms, or the rules for forming these terms in a particular field of arts or sciences. The principles of naming vary from the relatively informal conventions of everyday speech to the internationally agre ...
and
alpha taxonomy In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...
. When identifying material, a scientist attempts to apply a taxon name to a specimen or group of specimens based on his or her understanding of the relevant taxa, based on (at least) having read the type description(s), preferably also based on an examination of all the type material of all of the relevant taxa. If there is more than one named type that all appear to be the same taxon, then the oldest name takes precedence and is considered to be the correct name of the material in hand. If on the other hand, the taxon appears never to have been named at all, then the scientist or another qualified expert picks a type specimen and publishes a new name and an official description. This process is crucial to biological taxonomy. People's ideas of how living things should be grouped change over time. How do we know that what we call "''
Canis lupus The wolf (''Canis lupus''; : wolves), also known as the gray wolf or grey wolf, is a large canine native to Eurasia and North America. More than thirty subspecies of ''Canis lupus'' have been recognized, and gray wolves, as popularly u ...
''" is the same thing, or approximately the same thing, as what they will be calling "''Canis lupus''" in 200 years' time? It is possible to check this because there is a particular wolf specimen preserved in Sweden and everyone who uses that name– no matter what else they may mean by it – will include that particular specimen. Depending on the nomenclature code applied to the organism in question, a type can be a specimen, a culture, an illustration, or (under the bacteriological code) a description. Some codes consider a subordinate taxon to be the type, but under the botanical code, the type is always a specimen or illustration. For example, in the research collection of the Natural History Museum in London, there is a bird specimen numbered 1886.6.24.20. This is a specimen of a kind of bird commonly known as the spotted harrier, which currently bears the scientific name ''Circus assimilis''. This particular specimen is the holotype for that species; the name ''Circus assimilis'' refers, by definition, to the species of that particular specimen. That species was named and described by Jardine and Selby in 1828, and the holotype was placed in the museum collection so that other scientists might refer to it as necessary. Note that at least for type specimens there is no requirement for a "typical" individual to be used. 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. Hence, the term name-bearing type or onomatophore is sometimes used, to denote the fact that biological types do not define "typical" individuals or
taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
, but rather fix a scientific name to a specific
operational taxonomic unit An Operational Taxonomic Unit (OTU) is an operational definition used to classify groups of closely related individuals. The term was originally introduced in 1963 by Robert R. Sokal and Peter H. A. Sneath in the context of numerical taxonomy, w ...
. Type specimens are theoretically even allowed to be aberrant or deformed individuals or color variations, though this is rarely chosen to be 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 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 w ...
and zoology. In 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 ...
'', type-based definitions are replaced by phylogenetic definitions.


Older terminology

In some older taxonomic works the word "type" has sometimes been used differently. The meaning was similar in the first ''Laws of Botanical Nomenclature'', but has a meaning closer to the term taxon in some other works:
Translation: This single character permits
ne to NE, Ne or ne may refer to: Arts and entertainment * Neutral Evil, an alignment in the American role-playing game ''Dungeons & Dragons'' * New Edition, an American vocal group * Nicomachean Ethics, a collection of ten books by Greek philosopher Ar ...
distinguish this type from all other species of the section ... After studying the diverse forms, I came to consider them as belonging to the one and the same specific type.


In botany

In
botanical 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 ...
, a ''type'' (''typus'', ''nomenclatural type''), "is that element to which the name of a taxon is permanently attached." (article 7.2) 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). Examples of where an illustration may serve as a type include: * A detailed drawing, painting, etc., depicting the plant, from the early days of plant taxonomy. A dried plant was difficult to transport and hard to keep safe for the future; many specimens from the early days of botany have since been lost or damaged. Highly skilled botanical artists were sometimes employed by a botanist to make faithful and detailed illustrations. Some such illustrations have become the best record and have been chosen to serve as the type of taxon. * A detailed picture of something that can be seen only through a microscope. A tiny "plant" on a
microscope slide A microscope slide is a thin flat piece of glass, typically 75 by 26 mm (3 by 1 inches) and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is mounted (secured) on the slide, and then ...
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 does not determine the
circumscription Circumscription may refer to: *Circumscribed circle *Circumscription (logic) *Circumscription (taxonomy) * Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthrop ...
of the taxon. For example, the common
dandelion ''Taraxacum'' () is a large genus of flowering plants in the family Asteraceae, which consists of species commonly known as dandelions. The scientific and hobby study of the genus is known as taraxacology. The genus is native to Eurasia and Nor ...
is a controversial taxon: some botanists consider it to consist of over a hundred species, and others regard it as 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). The name ''Taraxacum officinale'' is the same and the type of the name is the same, but the extent to which the name actually applies varies greatly. Setting the circumscription of a taxon is done by a taxonomist in a publication. Miscellaneous notes: # Only a species or an
infraspecific taxon In botany, an infraspecific name is the scientific name for any taxon below the rank of species, i.e. an infraspecific taxon or infraspecies. (A "taxon", plural "taxa", is a group of organisms to be given a particular name.) The scientific names ...
can have a type of its own. For most new
taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
(published on or after 1 January 2007, article 37) at these ranks, a type should not be an illustration. # A genus has the same type as that of one of its
species In biology, a species is the basic unit of Taxonomy (biology), 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 ...
(article 10). # A family has the same type as that of one of its genera (article 10). The ''ICN'' provides a listing of the various kinds of types (article 9 and the Glossary), the most important of which is the holotype. These are * holotype – the single specimen or illustration that the author(s) clearly indicated to be the nomenclatural type of a name * lectotype – a specimen or illustration designated from the original material as the nomenclatural type when there was no holotype specified or the holotype has been lost or destroyed * isotype – a duplicate of the holotype * syntype – any specimen (or illustration) cited in the original description when there is no holotype, or any one of two or more specimens simultaneously designated as types * paratype – any specimen (or illustration) cited in the original description that is not the holotype nor an isotype, nor one of the syntypes * neotype – a specimen or illustration selected to serve as nomenclatural type if no material from the original description is available * epitype – a specimen or illustration selected to serve as an interpretative type, usually when another kind of type does not show the critical features needed for identification Note that the word "type" appears in botanical literature as a part of some older terms that have no status under the ''ICN'': for example a clonotype.


In zoology

In zoological nomenclature, the type of a species or subspecies is a specimen or series of specimens. The type of a genus or subgenus is a species. The type of a suprageneric taxon (e.g., family, etc.) is a genus. Names higher than superfamily rank do not have types. A "name-bearing type" is a specimen or image that "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 the basic unit of Taxonomy (biology), 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 ...
. For example, the type specimen for the species ''
Homo neanderthalensis Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...
'' was the specimen "Neanderthal-1" discovered by Johann Karl Fuhlrott in 1856 at Feldhofer in the Neander Valley in Germany, consisting of a
skullcap Skullcap or skull cap usually refers to various types of headgear. Specifically it may refer to: Headwear * Beanie (seamed cap) * Biretta, forming part of some clerical, academic or legal dress * Calotte (Belgium), a skullcap worn by students ...
, thigh bones, part of a pelvis, some ribs, and some arm and shoulder bones. There may be more than one type specimen, but there is (at least in modern times) only one holotype. * A type species is the nominal species that is the name-bearing type of a nominal genus or subgenus. * 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 ...
is the
nominal genus Nominal may refer to: Linguistics and grammar * Nominal (linguistics), one of the parts of speech * Nominal, the adjectival form of "noun", as in "nominal agreement" (= "noun agreement") * Nominal sentence, a sentence without a finite verb * Nou ...
that is the name-bearing type of a nominal family-group taxon. * The
type series In biology, a type is a particular 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 anchor or centralizes the ...
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 type specimens

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. A type description must include a diagnosis (typically, 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 . In the case of parasites, the term (or symbiotype) is used to indicate the host organism from which the type specimen was obtained. 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:


Holotype

When a single specimen is clearly designated in the original description, this specimen is known as the ''holotype'' of that species. The holotype is typically placed in a major museum, or similar well-known public collection, so that it is freely available for later examination by other biologists.


Paratype

When the original description designated a holotype, there may be additional specimens that the author designates as additional representatives of the same species, termed paratypes. These are not name-bearing types.


Allotype

An allotype is a specimen of the opposite sex to the holotype, designated from among paratypes. The word was also formerly used for a specimen that shows features not seen in the holotype of a fossil. The term is not regulated by the
ICZN 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 I ...
.


Neotype

A neotype is 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

A syntype is any one of two or more specimens that is listed in a species description where no holotype was designated; historically, syntypes were often explicitly designated as such, and under the present ICZN 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. Those that still exist are still considered name-bearing types.


Lectotype

A lectotype is a specimen later selected to serve as the single type specimen for species originally described from a set of syntypes. In zoology, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype. Having a single name-bearing type reduces the potential for confusion, especially considering that it is not uncommon for a series of syntypes to contain specimens of more than one species. A notable example is a suggestion that Carl Linnaeus should constitute the lectotype for the species '' Homo sapiens''.


Paralectotype

A paralectotype is any additional specimen from among a set of syntypes after a lectotype has been designated from among them. These are not name-bearing types.


Hapantotype

A special case in
Protistan A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the excl ...
s 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.


Iconotype

An illustration on which a new species or subspecies was based. For instance, the Burmese python, ''
Python bivittatus The Burmese python (''Python bivittatus'') is one of the largest species of snakes. It is native to a large area of Southeast Asia and is listed as Vulnerable on the IUCN Red List. Until 2009, it was considered a subspecies of the Indian python ...
,'' is one of many species that are based on illustrations by
Albertus Seba Albertus or Albert Seba (May 12, 1665, Etzel near Friedeburg – May 2, 1736, Amsterdam) was a Dutch pharmacist, zoologist, and collector. Seba accumulated one of the largest cabinets of curiosities in the Netherlands during his time. He sol ...
(1734).


Ergatotype

An ergatotype is a specimen selected to represent a worker member in
hymenopteran Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typica ...
s which have polymorphic castes.


Alternatives to preserved specimens

Type illustrations have also been used by zoologists, as in the case of the
Réunion parakeet The echo parakeet (''Psittacula eques'') is a species of parrot endemic to the Mascarene Islands of Mauritius and formerly Réunion. It is the only living native parrot of the Mascarene Islands; all others have become extinct due to human activit ...
, which is known only from historical illustrations and descriptions. Recently, some species have been described where the type specimen was released alive back into the wild, such as the Bulo Burti boubou (a
bushshrike The bushshrikes are smallish passerine birds. They were formerly classed with the true shrikes in the family Laniidae, but are now considered sufficiently distinctive to be separated from that group as the family Malaconotidae, a name that allude ...
), described as ''Laniarius liberatus'', in which the species description included DNA sequences from blood and feather samples. 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 for the future to designate a neotype for such a taxon, should any questions arise. However, in the case of the bushshrike, ornithologists have argued that the specimen was a rare and hitherto unknown
color morph In biology, polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative ''phenotypes'', in the population of a species. To be classified as such, morphs must occupy the same habitat at the s ...
of a long-known species, using only the available blood and feather samples. While there is still some debate on the need to deposit actual killed individuals as type specimens, it can be observed that given proper vouchering and storage, tissue samples can be just as valuable should dispute about the validity of a species arise.


Formalisation of the type system

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 the destruction of the 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 existed only since 1961 when the first edition of the Code was published. The ICZN does not always demand a type specimen for the historical validity of a species, and many "type-less" species do exist. The current edition of the Code, Article 75.3, prohibits the designation of a
neotype In biology, a type is a particular 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 anchor or centralizes th ...
unless there is "an exceptional need" for "clarifying the taxonomic status" of a species (Article 75.2). There are many other permutations and variations on terms using the suffix "-type" (e.g., allotype, cotype, topotype,
generitype In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...
, isotype, isoneotype, isolectotype, etc.) but these are not formally regulated by the Code, and a great many are obsolete and/or idiosyncratic. However, some of these categories can potentially apply to genuine type specimens, such as a neotype; e.g., isotypic/topotypic specimens are preferred to other specimens, when they are available at the time a neotype is chosen (because they are from the same time and/or place as the original type). 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 become much better known as the term for a different concept in genetics). 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).


Type genus

A type genus is a 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 that has passed into synonymy; the family name does not need to be changed in such a situation.


See also

*
Archetype The concept of an archetype (; ) appears in areas relating to behavior, historical psychology, and literary analysis. An archetype can be any of the following: # a statement, pattern of behavior, prototype, "first" form, or a main model that ot ...
*
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 abbreviat ...
*
Nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...
(zoology) * Nomen nudum * Genetypes – genetic sequence data from type specimens *
Pathotype A pathovar is a bacterial strain or set of strains with the same or similar characteristics, that is differentiated at infrasubspecific level from other strains of the same species or subspecies on the basis of distinctive pathogenicity to one o ...
– a type of intrasubspecific taxon of pathogenic bacteria * Principle of Typification


References


External links

* ''ICZN Code''
International Code of Zoological Nomenclature
the official website
Fishbase
Glossary section (archived)
A compendium of terms
(archived)
Zoological Type Nomenclature (Evenhuis)
(PDF) {{DEFAULTSORT:Type Biological concepts Taxonomy (biology) Zoological nomenclature Botanical nomenclature