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A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. Holotype_sentence_0

It is either the single such physical example (or illustration) or one of several such, but explicitly designated as the holotype. Holotype_sentence_1

Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. Holotype_sentence_2

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. Holotype_sentence_3

For example, the holotype for the butterfly Plebejus idas longinus is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University. Holotype_sentence_4

An isotype is a duplicate of the holotype and is often made for plants, where holotype and isotypes are often pieces from the same individual plant or samples from the same gathering. Holotype_sentence_5

A holotype is not necessarily "typical" of that taxon, although ideally it should be. Holotype_sentence_6

Sometimes just a fragment of an organism is the holotype, particularly in the case of a fossil. Holotype_sentence_7

For example, the holotype of Pelorosaurus humerocristatus (Duriatitan), a large herbivorous dinosaur from the early Jurassic period, is a fossil leg bone stored at the Natural History Museum in London. Holotype_sentence_8

Even if a better specimen is subsequently found, the holotype is not superseded. Holotype_sentence_9

Replacements for holotypes Holotype_section_0

Under the ICN, an additional and clarifying type could be designated an epitype under Article 9.8, where the original material is demonstrably ambiguous or insufficient. Holotype_sentence_10

A conserved type (ICN article 14.3) is sometimes used to correct a problem with a name which has been misapplied; this specimen replaces the original holotype. Holotype_sentence_11

In the absence of a holotype, another type may be selected, out of a range of different kinds of type, depending on the case, a lectotype or a neotype. Holotype_sentence_12

For example, in both the ICN and the ICZN a neotype is a type that was later appointed in the absence of the original holotype. Holotype_sentence_13

Additionally, under the ICZN the commission is empowered to replace a holotype with a neotype, when the holotype turns out to lack important diagnostic features needed to distinguish the species from its close relatives. Holotype_sentence_14

For example, the crocodile-like archosaurian reptile Parasuchus hislopi Lydekker, 1885 was described based on a premaxillary rostrum (part of the snout), but this is no longer sufficient to distinguish Parasuchus from its close relatives. Holotype_sentence_15

This made the name Parasuchus hislopi a nomen dubium. Holotype_sentence_16

Texan paleontologist Sankar Chatterjee proposed that a new type specimen, a complete skeleton, be designated. Holotype_sentence_17

The International Commission on Zoological Nomenclature considered the case and agreed to replace the original type specimen with the proposed neotype. Holotype_sentence_18

The procedures for the designation of a new type specimen when the original is lost come into play for some recent, high-profile species descriptions in which the specimen designated as the holotype was a living individual that was allowed to remain in the wild (e.g. a new species of capuchin monkey, genus Cebus, Marleyimyia xylocopae, or the Arunachal macaque Macaca munzala). Holotype_sentence_19

In such a case, there is no actual type specimen available for study, and the possibility exists that—should there be any perceived ambiguity in the identity of the species—subsequent authors can invoke various clauses in the ICZN Code that allow for the designation of a neotype. Holotype_sentence_20

Article 75.3.7 of the ICZN requires that the designation of a neotype must be accompanied by "a statement that the neotype is, or immediately upon publication has become, the property of a recognized scientific or educational institution, cited by name, that maintains a research collection, with proper facilities for preserving name-bearing types, and that makes them accessible for study", but there is no such requirement for a holotype. Holotype_sentence_21

See also Holotype_section_1


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Holotype.