REVISION OF THE BEACH-DWELLING SPECIES OF CERCYON LEACH (COLEOPTERA: HYDROPHILIDAE) OF THE WEST COAST OF NORTH AMERICA

摘要

Littoral species of Cercyon Leach occurring on coastlines of the West Coast of North America from Alaska to Mexico are reviewed based on material freshly collected in Washington State (USA) and British Columbia (Canada) and on museum specimens including primary types. Five species are recognized, including two that are distributed on both American and Eurasian sides of the Pacific Ocean and three that exist only on the American West Coast. The eastern Palearctic Cercyon dux Sharp is recorded in North America for the first time, with all known specimens collected after 2014. The synonymy of the western Nearctic Cercyon to ono Hatch with the eastern Palearctic Cercyon setulosus Sharp is confirmed. The previous concept of Cercyon fimbriatus Mannerheim, the most common and widespread species, is confirmed. Cercyon spathifer Smetana is placed in junior synonymy with Cercyon luniger Mannerheim, and the species previously treated as C. luniger is an unnamed species, described herein as Cercyon whuljensis Suzumura, new species. Redescriptions of all five species are given along with SEM photographs, illustrations, and maps based on examined material and literature data, and a key to species is provided.