Disarthricerus dulcissimus sp. nov. (Coleoptera, Staphylinidae, Pselaphinae): a precious dwarf from the north

The rare and enigmatic ant-like litter beetle genus Disarthricerus Raffray, 1895 (Pselaphinae, Clavigeritae, Disarthricerini) comprises three species distributed across the southern Malay Peninsula and northern Borneo. Herein, a fourth member, D. dulcissimus sp. nov. , is described from Yunnan, southwest China, which extends the known range of the genus northward by more than 2,100 kilometers. Scanning electron micrographs of the cephalic structures and illustrations of the aedeagus for the type species, D. integer Raffray, 1895, are provided for the first time. To facilitate future studies, a summary of existing knowledge of Disarthricerus and a key for the identification of all four species are also presented.