An aberrant species of Nipponocercyon from Sichuan, China (Coleoptera, Hydrophilidae, Sphaeridiinae)

Abstract. A detailed examination of specimens of Cryptopleurum sichuanicum Ryndevich, 2005 from high altitudes of Sichuan Province, China, revealed that the species belongs in the genus Nipponocercyon Satô, 1963 previously endemic to Japan. The species is here transferred in Nipponocercyon, and Nipponocercyon sichuanicus (Ryndevich, 2005), comb. n. is redescribed and compared with Nipponocercyon shibatai Satô, 1963. The male genitalia of Nipponocercyon sichuanicus is described for the first time. An adapted diagnosis of Nipponocercyon is provided, and reasons for the inclusion of Nipponocercyon sichuanicus into Nipponocercyon and the general distribution of the genus are discussed.