What is an ‘extant’ type specimen? Problems arising from naming mammalian species‐group taxa without preserved types

The International Code of Zoological Nomenclature allows the naming of new species without a type specimen ever having been preserved. This practice causes problems and is undesirable because if related, cryptic, sibling species are encountered later, it may not be possible either to allocate them with certainty to the earlier named species, or to determine them to be something different. We hypothesised that examination of the instances in which mammalian species were named without preserved types would reveal certain problems that are not unique to them, but are encountered more frequently than when types are preserved. We also thought the Code's stipulation that preserved types are not required in the case of specimens that are no longer ‘extant’ would present special problems hitherto unremarked upon in the literature. We conducted a review of cases involving putative new species of mammal named since 1900. These were analysed to see what special problems they present and the frequency of such problems. We found that the Code's waiver of the requirement that a type specimen be deposited in a collection if the specimen is no longer extant presents numerous problems—in particular, that a living-at-large type specimen can still be ‘extant’ even if its whereabouts are unknown at certain times and/or it may no longer be alive. Illustrations alone being used to designate type specimens is especially problematic, owing to mammals’ lack of meristic and other obvious distinguishing external characters. Hoaxes, the difficulty in determining that they are hoaxes, and various errors of taxonomic allocation appear to be especially common with names without preserved types. The Code should be revised to require preserved specimens as types for new names. Tissue samples alone for DNA analysis are not ideal for serving this purpose, but should be allowed to meet the requirement.