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

Xanthopygus as currently defined is the largest genus in Xanthopygina with 40 described species. However, the genus is poorly defined, 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 species were split into four different genera. Xanthopygus nigricornis Scheerpeltz was transferred to Oligotergus as Oligotergus nigricornis and Xanthopygus skalitzkyi was transferred to Styngetus as Styngetus skalitzkyi. A new genus, 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 and are provided to distinguish species in the new genus and Xanthopygus from each other and all other Xanthopygina genera.