Five New Species of Orthosinus Motschulsky, 1863 from China—Molecular Evidence for Two Species (Coleoptera, Curculionidae, Dryophthorinae)

Five new species of Orthosinus Motschulsky, 1863 from China are described: O. borisi sp. nov. (♂♀) and O. urceolatus sp. nov. (♂♀) from Xizang Autonomous Region, O. diaoluoshanensis sp. nov. (♂) from Hainan Province, O. sulcatus sp. nov. (♂♀) from Sichuan Province and O. tengchongensis sp. nov. (♂) from Yunnan Province. Detailed morphological descriptions, diagnostic illustrations, and habitus photographs are provided for each species. An identification key and a distribution map for all known Chinese species of Orthosinus are also provided. With these additions, the number of known Chinese species of Orthosinus is increased from two to seven. Molecular phylogenetic and species delimitation analyses of the COI gene were additionally performed for two of the newly described species, O. urceolatus sp. nov. and O. sulcatus sp. nov., along with other congeneric and outgroup specimens.