Out of Xanthopygus (Coleoptera: Staphylinidae): escape from polyphyly

Xanthopygus as currently defined is the largest genus in the subtribe Xanthopygina (Coleoptera: Staphylinidae: Staphylininae) with 40 described species. However, the genus is poorly defined, morphologically heterogeneous and previous studies have questioned whether it is a natural group. A morphological (51 characters) Bayesian phylogenetic analysis was performed to test whether Xanthopygus is a monophyletic group. The analysis indicated that Xanthopygus was polyphyletic, and therefore species were split into four different genera. Xanthopygusnigricornis Scheerpeltz was transferred to Oligotergus as Oligotergusnigricornis comb. nov. and Xanthopygusskalitzkyi (Bernhauer) was transferred to Styngetus as Styngetusskalitzkyi comb. nov. A new genus, Photinopygus gen. nov. was erected to accommodate the majority of the species previously in Xanthopygus and Xanthopygus sensu novo is used in a new restricted sense to accommodate the remaining species. Diagnostic features are provided to distinguish species in the genera Photinopygus and Xanthopygus from each other and all other Xanthopygina genera.