Callista chinensis
Similar to Callista florida. Costacallista chinensis is distinguishable by its more elongate shape, less inflated valves, and smaller, more elongate lunule. In addition, the hinge plates of C. chinensis are shorter dorso-ventrally and weaker than those of C. florida. The two species also have different distributions: C. florida is found on the coast of eastern Africa and in the Red Sea, and C. chinensis is found from Vietnam to Japan (Huber 2010).
The overall shape is elongate, ovate. The anterior, ventral and posterior margins are rounded; the posterior margin is slightly more pointed than the anterior. The anterior dorsal margin is nearly straight, and the posterior dorsal margin is subconvex. The valves are equal in size and shape (equivalve), and there is no gape when they are closed. Sculpture consists of growth lines and weak, wide comarginal ribs at the anterior only. The lunule is elongate, defined by a fine, shallow groove and extends half the anterior dorsal margin. The umbo is anterior, and the beaks also point slightly to the anterior. The escutcheon is not defined.
The exterior is white or tan. There are typically two wide, brown radial stripes near the umbo, and many more, thinner brown and/or purple radial stripes ventrally. The periostracum is light brown; if it is present, only the thinner, ventral radial stripes may be visible. There may also be purple-brown comarginal stripes. The interior is white.
The ligament is external, covers 1/3 of the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth, none of which are bifid. The anterior (2a) and central (2b) teeth are joined dorsally, forming an inverted "v" shape. The posterior tooth (4b) is fused with the nymph. There is also one anterior lateral tooth (A2) on the left valve. On the right valve, there are three cardinal teeth: the anterior (3a) and central (1) teeth are not bifid, and the posterior tooth (3b) is bifid. There are two anterior lateral teeth (A1, A3) on the right valve, as well as a fine, weak ridge that runs parallel to the posterior dorsal margin. The posterior adductor muscle scar is slightly larger and rounder than the anterior. The pallial sinus extends to the posterior end of the nymph in length, and its deepest point forms an acute angle.