Revision of the genus Xenonychus (Coleoptera: Histeridae)

Genus Xenonychus Wollaston, 1864 of the subfamily Saprininae is revised herein. It now contains three species: X. tridens (Jacquelin du Val, 1852), X. aralocaspius Kryzhanovskij, 1976 in KRYZHANOVSKIJ & REICHARDT (1976) and X. somaliensis (Therond, 1963) comb. nov. (transferred from Styphrus Motschulsky, 1845). The three species differ only in minor external characters. Xenonychus tridens and X. aralocaspius are most readily separated based on their male terminalia, especially aedeagi. All three species are diagnosed and their morphological differences are illustrated using SEM photographs. Male genitalia of X. aralocaspius and X. tridens are illustrated, and a key to the species is given.