Type (biology)

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"Type specimen" redirects here. Type (biology)_sentence_0

For the mineralogy term, see type specimen (mineralogy). Type (biology)_sentence_1

In biology, a type is a particular (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. Type (biology)_sentence_2

In other words, a type is an example that serves to anchor or centralize the defining features of that particular taxon. Type (biology)_sentence_3

In older usage (pre-1900 in botany), a type was a taxon rather than a specimen. Type (biology)_sentence_4

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. Type (biology)_sentence_5

Type specimen Type (biology)_section_0

According to a precise set of rules laid down in the International Code of Zoological Nomenclature (ICZN) and the International Code of Nomenclature for algae, fungi, and plants (ICN), the scientific name of every taxon is almost always based on one particular specimen, or in some cases specimens. Type (biology)_sentence_6

Types are of great significance to biologists, especially to taxonomists. Type (biology)_sentence_7

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. Type (biology)_sentence_8

Describing species and appointing type specimens is part of scientific nomenclature and alpha taxonomy. Type (biology)_sentence_9

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. Type (biology)_sentence_10

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. Type (biology)_sentence_11

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. Type (biology)_sentence_12

This process is crucial to biological taxonomy. Type (biology)_sentence_13

People's ideas of how living things should be grouped change over time. Type (biology)_sentence_14

How do we know that what we call "Canis lupus" is the same thing, or approximately the same thing, as what they will be calling "Canis lupus" in 200 years' time? Type (biology)_sentence_15

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. Type (biology)_sentence_16

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. Type (biology)_sentence_17

Some codes consider a subordinate taxon to be the type, but under the botanical code the type is always a specimen or illustration. Type (biology)_sentence_18

For example, in the research collection of the Natural History Museum in London, there is a bird specimen numbered 1886.6.24.20. Type (biology)_sentence_19

This is a specimen of a kind of bird commonly known as the spotted harrier, which currently bears the scientific name Circus assimilis. Type (biology)_sentence_20

This particular specimen is the holotype for that species; the name Circus assimilis refers, by definition, to the species of that particular specimen. Type (biology)_sentence_21

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. Type (biology)_sentence_22

Note that at least for type specimens there is no requirement for a "typical" individual to be used. Type (biology)_sentence_23

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. Type (biology)_sentence_24

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 . Type (biology)_sentence_25

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. Type (biology)_sentence_26

The usage of the term type is somewhat complicated by slightly different uses in botany and zoology. Type (biology)_sentence_27

In the PhyloCode, type-based definitions are replaced by phylogenetic definitions. Type (biology)_sentence_28

Older terminology Type (biology)_section_1

In some older taxonomic works the word "type" has sometimes been used differently. Type (biology)_sentence_29

The meaning was similar in the first Laws of Botanical Nomenclature, but has a meaning closer to the term taxon in some other works: Type (biology)_sentence_30

In botany Type (biology)_section_2

In botanical nomenclature, a type (typus, nomenclatural type), "is that element to which the name of a taxon is permanently attached." Type (biology)_sentence_31

(article 7.1) In botany a type is either a specimen or an illustration. Type (biology)_sentence_32

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). Type (biology)_sentence_33

Examples of where an illustration may serve as a type include: Type (biology)_sentence_34

Type (biology)_unordered_list_0

  • 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 a faithful and detailed illustration. Some such illustrations have become the best record and have been chosen to serve as the type of a taxon.Type (biology)_item_0_0
  • 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).Type (biology)_item_0_1

Note that a type does not determine the circumscription of the taxon. Type (biology)_sentence_35

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. Type (biology)_sentence_36

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). Type (biology)_sentence_37

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 greatly. Type (biology)_sentence_38

Setting the circumscription of a taxon is done by a taxonomist in a publication. Type (biology)_sentence_39

Miscellaneous notes: Type (biology)_sentence_40

Type (biology)_ordered_list_1

  1. 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.Type (biology)_item_1_2
  2. A genus has the same type as that of one of its species (article 10).Type (biology)_item_1_3
  3. A family has the same type as that of one of its genera (article 10).Type (biology)_item_1_4

The ICN provides a listing of the various kinds of type (article 9 and the Glossary), the most important of which is the holotype. Type (biology)_sentence_41

These are Type (biology)_sentence_42

Type (biology)_unordered_list_2

  • holotype – the single specimen or illustration that the author(s) clearly indicated to be the nomenclatural type of a nameType (biology)_item_2_5
  • 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 destroyedType (biology)_item_2_6
  • isotype – a duplicate of the holotypeType (biology)_item_2_7
  • 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 typesType (biology)_item_2_8
  • paratype – any specimen (or illustration) cited in the original description that is not the holotype nor an isotype, nor one of the syntypesType (biology)_item_2_9
  • neotype – a specimen or illustration selected to serve as nomenclatural type if no material from the original description is availableType (biology)_item_2_10
  • 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 identificationType (biology)_item_2_11

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. Type (biology)_sentence_43

In zoology Type (biology)_section_3

In zoological nomenclature, the type of a species or subspecies is a specimen, or series of specimens. Type (biology)_sentence_44

The type of a genus or subgenus is a species. Type (biology)_sentence_45

The type of a suprageneric taxon (e.g., family, etc.) is a genus. Type (biology)_sentence_46

Names higher than superfamily rank do not have types. Type (biology)_sentence_47

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." Type (biology)_sentence_48

Definitions Type (biology)_section_4

Type (biology)_unordered_list_3

  • 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.Type (biology)_item_3_12
  • A type species is the nominal species that is the name-bearing type of a nominal genus or subgenus.Type (biology)_item_3_13
  • A type genus is the nominal genus that is the name-bearing type of a nominal family-group taxon.Type (biology)_item_3_14
  • 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.Type (biology)_item_3_15

Use of type specimens Type (biology)_section_5

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. Type (biology)_sentence_49

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. Type (biology)_sentence_50

The geographical location where a type specimen was originally found is known as its type locality. Type (biology)_sentence_51

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. Type (biology)_sentence_52

Zoological collections are maintained by universities and museums. Type (biology)_sentence_53

Ensuring that types are kept in good condition and made available for examination by taxonomists are two important functions of such collections. Type (biology)_sentence_54

And, while there is only one holotype designated, there can be other "type" specimens, the following of which are formally defined: Type (biology)_sentence_55

Holotype Type (biology)_section_6

Main article: Holotype Type (biology)_sentence_56

When a single specimen is clearly designated in the original description, this specimen is known as the holotype of that species. Type (biology)_sentence_57

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. Type (biology)_sentence_58

Paratype Type (biology)_section_7

Main article: Paratype Type (biology)_sentence_59

When the original description designated a holotype, there may still be additional specimens listed in the type series and those are termed paratypes. Type (biology)_sentence_60

These are not name-bearing types. Type (biology)_sentence_61

Allotype Type (biology)_section_8

An allotype is a specimen of the opposite sex to the holotype, designated from among paratypes. Type (biology)_sentence_62

The word was also formerly used for a specimen that shows features not seen in the holotype of a fossil. Type (biology)_sentence_63

The term is not regulated by the ICZN. Type (biology)_sentence_64

Neotype Type (biology)_section_9

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. Type (biology)_sentence_65

Syntype Type (biology)_section_10

Main article: Syntype Type (biology)_sentence_66

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. Type (biology)_sentence_67

Those that still exist are still considered name-bearing types. Type (biology)_sentence_68

Lectotype Type (biology)_section_11

A lectotype is a specimen later selected to serve as the single type specimen for species originally described from a set of syntypes. Type (biology)_sentence_69

In zoology, a lectotype is a kind of name-bearing type. Type (biology)_sentence_70

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. Type (biology)_sentence_71

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. Type (biology)_sentence_72

A notable example is that Carl Linnaeus is the lectotype for the species Homo sapiens. Type (biology)_sentence_73

Paralectotype Type (biology)_section_12

A paralectotype is any additional specimen from among a set of syntypes, after a lectotype has been designated from among them. Type (biology)_sentence_74

These are not name-bearing types. Type (biology)_sentence_75

Hapantotype Type (biology)_section_13

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. Type (biology)_sentence_76

Iconotype Type (biology)_section_14

An illustration on which a new species or subspecies was based. Type (biology)_sentence_77

For instance, the Burmese python, Python bivittatus, is one of many species that are based on illustrations by Albertus Seba (1734). Type (biology)_sentence_78

Ergatotype Type (biology)_section_15

An ergatotype is a specimen selected to represent a worker member in hymenopterans which have polymorphic castes. Type (biology)_sentence_79

Alternatives to preserved specimens Type (biology)_section_16

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. Type (biology)_sentence_80

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. Type (biology)_sentence_81

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. Type (biology)_sentence_82

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. Type (biology)_sentence_83

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 disputes about the validity of a species arise. Type (biology)_sentence_84

Formalisation of the type system Type (biology)_section_17

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. Type (biology)_sentence_85

Also, types were not always carefully preserved, and intervening events such as wars and fires have resulted in destruction of original type material. Type (biology)_sentence_86

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. Type (biology)_sentence_87

The ICZN has existed only since 1961, when the first edition of the Code was published. Type (biology)_sentence_88

The ICZN does not always demand a type specimen for the historical validity of a species, and many "type-less" species do exist. Type (biology)_sentence_89

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). Type (biology)_sentence_90

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. Type (biology)_sentence_91

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). Type (biology)_sentence_92

The term fixation is used by the Code for the declaration of a name-bearing type, whether by original or subsequent designation. Type (biology)_sentence_93

Type species Type (biology)_section_18

Main article: Type species Type (biology)_sentence_94

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). Type (biology)_sentence_95

The description of a genus is usually based primarily on its type species, modified and expanded by the features of other included species. Type (biology)_sentence_96

The generic name is permanently associated with the name-bearing type of its type species. Type (biology)_sentence_97

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. Type (biology)_sentence_98

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 (biology)_sentence_99

Type genus Type (biology)_section_19

Main article: Type genus Type (biology)_sentence_100

A type genus is that genus from which the name of a family or subfamily is formed. Type (biology)_sentence_101

As with type species, the type genus is not necessarily the most representative, but is usually the earliest described, largest or best known genus. Type (biology)_sentence_102

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. Type (biology)_sentence_103

See also Type (biology)_section_20

Type (biology)_unordered_list_4

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Type (biology).