The forgotten type specimen of the grey seal [ Halichoerus grypus (Fabricius, 1791)] from the island of Amager, Denmark

The conservation and management of biological diversity rely heavily on clear definitions of appropriate target units, such as populations, subspecies and species. However, the nomenclature of the grey seal [ Halichoerus grypus (Fabricius 1791)] has for many years been misled by two persistent assumptions; that there was no type specimen for the species and that the type locality lay in Greenland. Here, we describe a grey seal skull held in the collections of the Natural History Museum of Denmark, and present written and morphological evidence to demonstrate that this skull is identical to Fabricius’ original specimen collected in 1788 near Copenhagen on the island of Amager, Denmark. In addition, we perform genetic analyses to clearly affiliate this specimen with the Baltic grey seal subspecies. Accordingly, we appoint this specimen ( ZMUC M11‐1525) the holotype of the grey seal and the island of Amager, Denmark, the type locality of the species. Hereby, the Baltic subspecies of the grey seal by definition becomes the nominate race of the species to henceforth be classified as Halichoerus grypus grypus , putting the hitherto used subspecies name macrorhynchus in reference to Hornschuch & Schilling (1850) in junior synonymy. As a further consequence, we resurrect Halichoerus grypus atlantica in reference to Nehring (1886) as the earliest available name for the Atlantic subspecies. The type specimen's digital, morphological and genetic data are made publicly available for future reference and as an inspiration for baseline data to include in descriptions of other type specimens.