Xanthopygusas 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 whetherXanthopygusis a monophyletic group. The analysis indicated thatXanthopyguswas polyphyletic, and therefore species were split into four different genera.Xanthopygus nigricornisScheerpeltz was transferred toOligotergusasOligotergus nigricorniscomb. nov.andXanthopygus skalitzkyi(Bernhauer) was transferred toStyngetusasStyngetus skalitzkyicomb. nov.A new genus,Photinopygusgen. nov.was erected to accommodate the majority of the species previously inXanthopygusandXanthopygussensu novo is used in a new restricted sense to accommodate the remaining species. Diagnostic features are provided to distinguish species in the generaPhotinopygusandXanthopygusfrom each other and all other Xanthopygina genera.
