Apatodemus degiulii n. gen. et sp. (Rodentia, Muridae), a hitherto undescribed endemite from the Terre Rosse of Gargano (Late Miocene, Southeastern Italy)

The taxonomy of the murid that had been ascribed to the genus Apodemus from the late Miocene insular faunal assemblages of Gargano (Southeastern Italy) is revised. Morphological and odontometric analyses of important new dental characters were undertaken. Our investigations revealed substantial morphological differences from Apodemus. The rodent is therefore assigned to a new genus and species, Apatodemus degiulii. The new species is characterised by a combination of advanced and primitive characters: moderately brachyodont teeth, t7 present in all M1–2s, elongated and distally located t1 in M1, t1 often twinned in M1–2, and narrow labial cingulid in lower molars associated to a well-developed tma. The genus Apatodemus actually includes two distinct species of different age. A. degiulii is the oldest and is described here in detail. The other one, for the moment, is referred to as Apatodemus sp.: a more comprehensive description of it will be presented in a future publication. Apatodemus sp. is a highly modified, endemic species, whereas A. degiulii is slightly endemized. Despite the features of Apatodemus degiulii render difficult to asses its closest continental ancestor, the species likely originated from some south-eastern European stock, in agreement with paleo-geographical reconstructions suggesting periodic connections of the Abruzzo-Apulian paleobioprovince with the Balkan mainland. The age when the ancestor of Apatodemus reached the Apulia Platform is still unclear. However, some lines of evidence suggest a probable arrival at the time of the MN13 unit (latest Miocene).