Rediscovery of Macroplea japana (Coleoptera: Chrysomelidae: Donaciinae), an aquatic leaf beetle once thought to be extinct in Japan

Macroplea japana (Jacoby, 1885) has not been collected in Japan since the 1960s and was thought to be locally extinct. Recently, we collected this species from submerged aquatic plants growing in the nearshore zone of Lake Biwa, Shiga Prefecture, where it had previously been recorded from the stomach contents of pochards in the 1950s. We conducted a molecular phylogenetic analysis to identify the phylogenetic position of the Japanese M. japana within the tribe Haemonini of the Holarctic region, which consists of Macroplea in Eurasia and Neohaemonia in North America. We found that M. japana specimens from Japan and China were genetically close to each other and distantly related to all other known Macroplea species from Asia and Europe, indicating the species identity of the Japanese and Chinese populations and the distinct species status of M. japana.