The bivalve genus Sunetta Link, 1807 (Heterodonta: Veneridae) of Japan and the neighbouring waters–a taxonomic revision with the descriptions of three new species

Species of Sunetta Link, 1807 from Japan and the neighbouring regions (Korea, China and Taiwan) are revised taxonomically. Eight species of the subgenus Sunemeroe Iredale, 1930 are recognised: Sunetta beni n.sp., S. crassatelliformis Haga and H. Fukuda, n.sp., S. cumingii E.A. Smith, 1891, S. kirai Huber, 2010, S. langfordi (Habe, 1953), S. menstrualis (Menke, 1843) S. nomurai Haga and H. Fukuda, n.sp., and S. sunettina (Jousseaume, 1891). Although S. beni has long been misidentified as S. solanderii (Gray, 1825) from the Indian Ocean, it is distinguishable from all other Sunemeroe species in having a small, oval and inflated shell with a round posterior end and a broad and deeply sunken escutcheon. Sunetta crassatelliformis is a Lower Pleistocene species endemic to Japan. Another fossil species S. nomurai is known from the Pleistocene of Taiwan. Sunetta cumingii, a little-known Recent species from southwestern Japan and Taiwan, is separable from S. sunettina (= S. contempta E.A. Smith, 1891), which has often been regarded as synonymous. Amongst the six Recent species only S. sunettina is widely distributed in the Indo-West Pacific; the other five have narrower geographical ranges around Japan. Sunetta beni and S. menstrualis are thought to be threatened due to habitat loss.