A New Species of Ctenocardia (Bivalvia: Cardiidae) Dredged off Southern Japan

Abstract

A new cardiid species of the subfamily Fraginae, Ctenocardia excavata n. sp., is described from the southern parts of Japan, from the Kii Peninsula to Okinawa Islands. It represents the sole Ctenocardia whose northern distribution limit reaches southern Honshu. It is characterized by a deeply excavated posterior margin, a relatively high rib number (44–49), and a rib sculpture consisting of knobby scales on the umbonal keel.