A New Species of the Genus Lanceolaria (Bivalvia: Unionidae) from Japan

Abstract

A new unionid species Lanceolaria kihirai n. sp. is described from the Futatsukawa Creek, Yanagawa City, Fukuoka Prefecture and the Matsuura River, Karatsu City, Saga Prefecture, Kyushu, Japan. L. kihirai n. sp. differs from L. triformis and L. lanceolata in having a non-twisted shell, and from L. oxyrhyncha and L. grayii in having a round posterior ridge. Moreover, the posterior ridge is prominent from beak to the posterior end in L. oxyrhyncha, L. grayii, L. gladiola and L. acrorrhyncha, while gradually becoming obscure toward the posterior end in L. kihirai n. sp.