First record of Omalium japonicum Sharp (Coleoptera, Staphylinidae) from China with descriptions of its diagnoses

Omalium japonicum Sharp is recorded from Sheshan, Shanghai, and Dongshan, Jiansu, China. This species originally described by Sharp (1874) from Japan is new to China. Its major characters are redescribed and illustrated in this paper. Omalium japonicum is similar to Omalium niponense Sharp, but can be readily distinguished from the latter by the following characters : Media lobe of male genital organ abruptly thicked in ventral view, the apex of media lobe of male genital organ is harpoon-shaped in profile.