Cafius semiaereus (Cameron), a New Synonym of Cafius cupreipennis (Cameron) (Coleoptera: Staphylinidae: Staphylininae)

While working on the marine littoral Cafius Stephens (Coleoptera: Staphylinidae: Staphylininae), we found that Cafius cupreipennis (Cameron, 1918) and Cafius semiaereus (Cameron, 1934) correspond in many characters. Cameron (1934) also noted that these two species were similar except for the body coloration. This led us to study the taxonomic status of these two species in more detail. Examination of the types of C. cupreipennis and C. semiaereus (Fig. 1) deposited in the Natural History Museum (BMNH, London) revealed that they represent the same species. They share the same diagnostic characters as follows: glossy head and pronotum; subquadrate head and pronotum; pronotum with dorsal median longitudinal rows with 4–5 setiferous punctures; same pubescence and microsculpture pattern of pronotum (microsculpture and setae absent on dorsal surface); anterior-lateral corner of pronotum forming right angle; less dense setae on elytron. Based on these characters, we synonymize C. semiaereus under C. cupreipennis and provide illustrations of the diagnostic characters (Fig. 2) of C. cupreipennis. Specimens examined are from BMNH and Chungnam National University Insect Collection, Daejeon, South Korea (CNUIC). A backslash (\) was used between labels for label transcription notation.