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 associated. 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.[1]
A taxon is a scientifically named grouping of organisms with other like organisms, a set that includes some organisms and excludes others, based on a detailed published description (for example a species description) and on the provision of type material, which is usually available to scientists for examination in a major museum research collection, or similar institution.[1][2]
When identifying material, a scientist attempts to apply a taxon name to a specimen or group of specimens based on their understanding of the relevant taxa,[clarification needed][citation needed] based on (at least) having read the type description(s),[citation needed] 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.[citation needed]
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.[citation needed]
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.[citation needed]
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 systematicscannot 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, but rather fix a scientific name to a specific operational taxonomic unit. 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.[1][2][4]
In some older taxonomic works the word "type" has sometimes been used differently. The meaning was similar in the first Laws of Botanical Nomenclature,[5][6] but has a meaning closer to the term taxon in some other works:[7]
Ce seul caractère permet de distinguer ce type de toutes les autres espèces de la section. ... Après avoir étudié ces diverses formes, j'en arrivai à les considérer comme appartenant à un seul et même type spécifique.
Translation: This single character permits [one to] 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, a type (typus, nomenclatural type), "is that element to which the name of a taxon is permanently attached." (article 7.2)[8] 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 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).
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, 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 can have a type of its own. For most new taxa (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 (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),[8] 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
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 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."[citation needed]
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. 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. There may be more than one type specimen, but there is (at least in modern times) only one holotype.
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.
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.[citation needed]
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 type locality. In the case of parasites, the term type host (or symbiotype) is used to indicate the host organism from which the type specimen was obtained.[9]
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:
When a single specimen is clearly designated in the original description, this specimen is known as the holotype of that species.[10] 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.
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.[citation needed]
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.[11] The term is not regulated by the ICZN.[citation needed]
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.
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.[citation needed]
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 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.[13]
Hapantotype
A special case in Protistans where the type consists of two or more specimens of "directly related individuals" within a preparation medium such as a blood smear. The terms parahapantotype and lectohapantotype refer to type preparations additional to the hapantotype and designated by the describing author.[14] As with other type designations the use of the prefix "Neo-", such as Neohapantotype, is employed when a replacement for the original hapantotype is designated, or when an original description did not include a designated type specimen.[15]
Iconotype
An illustration on which a new species or subspecies was based. For instance, the Burmese python, Python bivittatus, is one of many species that are based on illustrations by Albertus Seba (1734).[16][17]
Ergatotype
An ergatotype is a specimen selected to represent a worker member in hymenopterans which have polymorphic castes.[11]
The term "kleptotype" informally refers to a type specimen or a part of it that has been stolen, or improperly relocated.[19][20][21][22]
Alternatives to preserved specimens
Type illustrations have also been used by zoologists, as in the case of the Réunion parakeet, which is known only from historical illustrations and descriptions.[23]:24
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), 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 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.[citation needed]
Formalisation of the type system
The various types listed above are necessary[citation needed] 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 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, 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).[citation needed] A topotype is a specimen that was obtained from the same location that the original type specimen came from.[24]
The term fixation is used by the Code for the declaration of a name-bearing type, whether by original or subsequent designation.[citation needed]
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.[citation needed]
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).[citation needed]
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.[citation needed]
Genus is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
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 International Commission on Zoological Nomenclature. The rules principally regulate:
In biology, a taxon 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 name and given a particular ranking, especially if and when it is accepted or becomes established. It is very common, however, for taxonomists to remain at odds over what belongs to a taxon and the criteria used for inclusion, especially in the context of rank-based ("Linnaean") nomenclature. If a taxon is given a formal scientific name, its use is then governed by one of the nomenclature codes specifying which scientific name is correct for a particular grouping.
A holotype is a single physical example of an organism used when the species was formally described. It is either the single such physical example or one of several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept.
In zoological nomenclature, a type species 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. 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.
A botanical name is a formal scientific name conforming to the International Code of Nomenclature for algae, fungi, and plants (ICN) and, if it concerns a plant cultigen, the additional cultivar or Group epithets must conform to the International Code of Nomenclature for Cultivated Plants (ICNCP). The code of nomenclature covers "all organisms traditionally treated as algae, fungi, or plants, whether fossil or non-fossil, including blue-green algae (Cyanobacteria), chytrids, oomycetes, slime moulds and photosynthetic protists with their taxonomically related non-photosynthetic groups ."
In binomial nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application.
In biological nomenclature, a syntype is any one of two or more biological types that is listed in a description of a taxon where no holotype was designated. Precise definitions of this and related terms for types have been established as part of the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants.
A tautonym is a scientific name of a species in which both parts of the name have the same spelling, such as 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 in the International Code of Nomenclature for algae, fungi, and plants and the specific name in the International Code of Zoological Nomenclature.
Nomenclature codes or codes of nomenclature are the various rulebooks that govern the naming of living organisms. Standardizing the scientific names of biological organisms allows researchers to discuss findings.
A conserved name or nomen conservandum is a scientific name that has specific nomenclatural protection. That is, the name is retained, even though it violates one or more rules which would otherwise prevent it from being legitimate. Nomen conservandum is a Latin term, meaning "a name to be conserved". The terms are often used interchangeably, such as by the International Code of Nomenclature for Algae, Fungi, and Plants (ICN), while the International Code of Zoological Nomenclature favours the term "conserved name".
Parasuchus is an extinct genus of basal phytosaur known from the Late Triassic of Andhra Pradesh and Madhya Pradesh, India. At its most restricted definition, Parasuchus contains a single species, Parasuchus hislopi. Parasuchus hislopi is one of several species belonging to a basal grade of phytosaurs, typified by the genus Paleorhinus. Historically, Paleorhinus has been known from better-described fossils, and many species have been lumped into that genus. Parasuchus hislopi, despite being described earlier than Paleorhinus, was considered an undiagnostic chimera until new neotype fossils were described in the late 1970s. Parasuchus hislopi and the two unambiguously valid species of Paleorhinus are all closely related; some authors have historically described them all under the species Paleorhinus, while others place the two Paleorhinus species into Parasuchus according to the principle of priority.
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. Often there is more than one paratype. Paratypes are usually held in museum research collections.
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
Macropterygius is a genus of ichthyosaurs known from the Late Jurassic of England. Though many specimens have been referred to this genus from all over Europe, the type specimen of the only recognized species, M. trigonus, consists of just a single vertebra. Because this cannot be used to distinguish ichthyosaurs from one another, the genus and species are currently considered nomina dubia.
In zoological nomenclature, an available name is a scientific name for a taxon of animals that has been published after 1757 and conforming to all the mandatory provisions of the International Code of Zoological Nomenclature for the establishment of a zoological name.
In biology, taxonomic rank is the relative level of a group of organisms in an ancestral or hereditary hierarchy. A common system of biological classification (taxonomy) consists of species, genus, family, order, class, phylum, kingdom, and domain. While older approaches to taxonomic classification were phenomenological, forming groups on the basis of similarities in appearance, organic structure and behaviour, methods based on genetic analysis have opened the road to cladistics.
Under the International Code of Zoological Nomenclature (Code), the name-bearing type or onomatophore 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. The name-bearing type can be either a type genus, type species, or one or more type specimens. For example, the name Mabuya maculata has often been used for the Noronha skink, but because the name-bearing type of the former, a lizard preserved in the Muséum national d'histoire naturelle in Paris, does not represent the same species as the Noronha skink, the name maculata cannot be used for the latter.
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 abbreviations are used with or without a stop.
↑ "Plant names – a basic introduction". Australian National Botanic Gardens, Centre for Australian National Biodiversity Research. Retrieved 17 November 2015.
↑ Frey, Jennifer K.; Yates, Terry L.; Duszynski, Donald W.; Gannon, William L. & Gardner, Scott L. (1992). "Designation and Curatorial Management of Type Host Specimens (Symbiotypes) for New Parasite Species". The Journal of Parasitology. 78 (5): 930–993. doi:10.2307/3283335. JSTOR3283335. S2CID82003952.
↑ Stearn, W. T. (1 March 1959). "The Background of Linnaeus's Contributions to the Nomenclature and Methods of Systematic Biology". Systematic Biology. 8 (1): 4–22. doi:10.2307/sysbio/8.1.4. ISSN1063-5157.
↑ Hansen, Hans V.; Seberg, Ole (1984). "Paralectotype, a new type term in botany". Taxon. 33 (4): 707–711. doi:10.2307/1220790. JSTOR1220790.
↑ Peirce, M. A.; Bennett, G. F. (1992). "Neohapantotype and paraneohapantotypes of Haemoproteus passeris Kruse, 1890". Journal of natural history. 26 (3): 689-690.
↑ Bauer, Aaron M. (2002). "Albertus Seba, Cabinet of Natural Curiosities. The Complete Plates in Colour, 1734–1765. 2001". International Society for the History and Bibliography of Herpetology. 3.
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