Phylogenetic analysis and reclassification of the genus Priochirus sharp (Coleoptera: Staphylinidae: Osoriinae)

The genus Priochirus Sharp (Coleoptera: Staphylinidae) is a rove beetle group with great variation in cephalic structures, especially the teeth on the frontal margin of head. In this paper, phylogenetic relationships among ten subgenera of the genus Priochirus sensu lato, and of Priochirus and other genera of the tribe Leptochirini are analysed. A cladistic analysis was conducted based on 62 characters of adult morphology. Results indicate that the genus Priochirus is not a monophyletic group and is divided into two lineages ( called here Lineages I and II respectively). The subgenus Euleptarthrus Jakobson, which included three species-groups (japonicus, longicornis and malayanus), is shown to be polyphyletic. Lineage I corresponds with the Leiochirus + (Exochirus + Syncampsochirus) + (Eutriacanthus + (Plastus + (japonicus- group of Euleptarthrus + (Barychirus + Stigmatochirus)))) clade and forms a sister group to the genus Thoracochirus Bernhauer. Lineage II corresponds with the Priochirus, s. str. + (Cephalomerus + (longicornis- and malayanus-group of the Euleptarthrus)) clade. In addition, the analysis reveals sister relationships between representatives of Lineage I and the genus Thoracochirus. On the basis of phylogenetic inference, the genus Plastus Bernhauer, stat. nov. is proposed to include the subgenera of Lineage I and a new subgenus Sinumandibulus, subgen. nov., which is erected for the japonicus- group of the former subgenus Euleptarthrus. The genus Priochirus Sharp sensu novo is redefined to include the subgenera of Lineage II. Seven new species are described from China: Plastus (Sinumandibulus) curvaticornis, sp. nov. from Sichuan; Plastus (Sinumandibulus) recticornis, sp. nov. from Hubei; Priochirus (Euleptarthrus) amblyodontus, sp. nov. from Hunan; Priochirus (Euleptarthrus) baoxingensis, sp. nov. from Sichuan, Priochirus (Euleptarthrus) elongates, sp. nov. from Guizhou, Priochirus (Euleptarthrus) parvicornis, sp. nov. from Fujian and Priochirus (Euleptarthrus) oxygonus, sp. nov. from Hainan.