Shell medium-sized, equivalve and solid with a triangular ovate shape. Sculpture consists of numerous fine concentric lines and growth pauses. Anterior margin rounded, posterior margin attenuate. Ventral margin regularly arched. Anterior dorsal margin straight, postero-dorsal margin steeply sloping. Umbones slightly inflated, beaks nearly touching. Lunule narrow and elongate. Hinge strong with three cardinal teeth at each valve, pallial sinus rounded. Color externally white with blue-gray markings and comarginal bands, internally white. This is the type species of the subgenus.Distribution: Vung Tau, Phan Thiet, Mui Ne, Long Hai, Quy Nhon, Da Nang, Hoi An, etc. Size: 25-50 mm