The systematic position of Placusa Erichson and Euvira Sharp: the tribe Placusini described (Coleoptera: Staphylinidae: Aleocharinae)

Abstract

Abstract. The genera Placusa Mannerheim and Euvira Sharp share the 4, 4, 5 tarsal segmentation with other members of the aleocharine tribe Bolitocharini. Placusa has usually been placed together with other subcortical members of this tribe into the subtribe Homalotina or its taxonomic equivalent. Members of the very distinctive genus Euvira are not subcortical. The systematic position of this latter genus has been uncertain though it has been most often placed in the tribe (or subtribe) Autaliini. Because of the striking differences in habitus and habits of members of these two genera, they have always been considered to be, at most, distantly related within the Bolitocharini. Study of the larvae and adults of both genera has revealed that they share a diverse set of derived features (eight in adults; ten in larvae). Many of these are unique to the Aleocharinae. These features are described and illustrated and a discussion of their systematic importance is provided. Four conclusions are drawn: (1) Placusa and Euvira form a monophyletic group; (2) these two genera are misplaced in the tribe Bolitocharini; (3) these two genera do not share derived features with members of any other described tribe of aleocharines; and (4) Placusa and Euvira must be grouped into a redefined tribal level taxon, the Placusini. The tribe Placusini is defined and its composition and systematic placement discussed.