Nomen dubium

This may happen if the original type series (i. e. holotype, isotype, syntype or paratype) is lost or destroyed.

A name may also be considered a nomen dubium if its name-bearing type is fragmentary or lacking important diagnostic features (this is often the case for species known only as fossils).

To preserve stability of names, the International Code of Zoological Nomenclature allows a new type specimen, or neotype, to be chosen for a nomen dubium in this case.

When an author considers that the taxonomic identity of a nominal species-group taxon cannot be determined from its existing name-bearing type (i.e. its name is a nomen dubium), and stability or universality are threatened thereby, the author may request the Commission to set aside under its plenary power [Art.

[2] The International Commission on Zoological Nomenclature considered the case and agreed in 2003 to replace the original type specimen with the proposed neotype.