Holotype

Holotype

A holotype is one of several possible biological types. A type is what fixes a name to a taxon. A holotype is a single physical example (or illustration) of an organism, known to be used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several such, but explicitly designated as the holotype.

For example, the holotype for the butterfly "Lycaeides idas longinus" is held by the Museum of Comparative Zoology at Harvard University, and the holotype for the extinct mammal "Cimolodon" is at the University of Alberta.

A holotype is not necessarily 'typical' of that taxon, although ideally it should be. Sometimes just a fragment of an organism is the holotype, for example in the case of a rare fossil. The holotype of "Pelorosaurus humerocristatus", a large herbivore dinosaur from the early Jurassic period, is a fossil leg bone stored at the Natural History Museum in London. Under unusual circumstances even a good quality photograph can be submitted as holotype. Even if a better specimen is subsequently found, the holotype is not superseded.

In the absence of a holotype (e.g. it was lost) another type may be selected, out of a range of different kinds of type, depending on the case. Note that in the "ICBN" and "ICZN" the definitions of types are similar in intent but not identical in terminology or underlying concept.

For example in both the "ICBN" and the "ICZN" a "neotype" is a type that was later appointed in the absence of the original holotype. 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. 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. This made the name "Parasuchus hislopi" a "nomen dubium". Texan paleontologist Sankar Chatterjee proposed that a new type specimen, a complete skeleton, be designated. [Case 3165, [http://www.iczn.org/BZNMar2001cases.htm "Bulletin of Zoological Nomenclature" 58:1] , 30 March 2001.] The International Commission on Zoological Nomenclature considered the case and agreed to replace the original type specimen with the proposed neotype. [Opinion 2045, [http://www.iczn.org/BZNJune2003opinions.htm "Bulletin of Zoological Nomenclature" 60:2] , 30 June 2003.] .

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., [Mendes Pontes, A.R., Malta A. and Asfora, P.H. 2006. A new species of capuchin monkey, genus "Cebus" Erxleben (Cebidae, Primates): found at the very brink of extinction in the Pernambuco Endemism Centre. Zootaxa 1200: 1-12.] [Sinha, A.,Datta, A., Madhusudan, M. D. and Mishra, C. (2004). "The Arunachal macaque "Macaca munzala": a new species from western Arunachal Pradesh, northeastern India". International Journal of Primatology volume: 26 issue: 977 pages: 989.] ). 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. Remarkably, the Code explicitly states that the designation of a neotype must be based upon an actual physical specimen that is "the property of a recognized scientific or educational institution", but there is no such requirement for a holotype.

Under the "ICBN", also, a replacement type could be appointed by such a procedure, but this would be called a "conserved type". However, a conserved type would not be appointed in the case of a type that is insufficiently clear: in that case an additional and clarifying type could be designated, a so-called "epitype". Great care must be used in speaking of types, as definitions are very precise.

ee also

* biological type
* paratype (zoology)
* allotype

References


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  • holotype — ● holotype nom masculin Individu à partir duquel une espèce végétale ou animale a été décrite pour la première fois et qui sert de référence. (On dit aussi type.) holotype [ɔlɔtip] n. m. ÉTYM. Mil. XXe; de holo , et type. ❖ ♦ Didact. (sc.).… …   Encyclopédie Universelle

  • holotype — [häl′ō tīp΄, hō′lətīp΄] n. [ HOLO + TYPE] Taxonomy the single specimen chosen as the type of a new species or subspecies in the original description holotypic [häl′ōtip′ik, hō′lətip′ik] adj …   English World dictionary

  • Holotype — Type (biologie) Pour les articles homonymes, voir Type (homonymie). En sciences de la vie, un type est un élément de référence attaché à un nom scientifique[1] (et non pas à un taxon), à partir duquel une espèce vivante (ou ayant vécu), a été… …   Wikipédia en Français

  • holotype — the single specimen designated or indicated as “the type specimen of a nominal species group taxon (species or subspecies) by the author at the time of the original publication (or the single specimen when no type was specified but only one… …   Dictionary of ichthyology

  • holotype — noun Date: 1897 1. the single specimen designated by an author as the type of a species or lesser taxon at the time of establishing the group 2. the type of a species or lesser taxon designated at a date later than that of establishing a group or …   New Collegiate Dictionary

  • holotype — n. [Gr. holos, whole; typos, type] The single specimen designated or indicated as the type specimen by the original author at the time of original publication of a species …   Dictionary of invertebrate zoology

  • holotype — holotypic /hol euh tip ik, hoh leuh /, adj. /hol euh tuyp , hoh leuh /, n. Biol. the type specimen used in the original description of a species. [1895 1900; HOLO + TYPE] * * * …   Universalium

  • holotype — noun The single physical example (or illustration) of an organism, known to be used when the taxon was formally described …   Wiktionary

  • holotype — The single specimen used as the basis of the original published description of a species and later designated as the type specimen [AHD] …   Crustacea glossary

  • holotype — ho·lo·type hō lə .tīp, häl ə n 1) the single specimen designated by an author as the type of a species or lesser taxon at the time of establishing the group 2) the type of a species or lesser taxon designated at a date later than that of… …   Medical dictionary

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