Holotype

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.

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.

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

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

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.