Callista erycina
Similar to Callista grata. Callista erycina is distinguishable by its slightly less elongate shape and more convex posterior dorsal margin. In addition, the hinge plate of C. erycina is taller dorso-ventrally and slightly more robust than that of C. grata. C. erycina does not have interior pigmentation; whereas, C. grata has an internal ray of purple coloration at its posterior margin.
Similar to Callista planatella. Callista erycina is less elongate and rounder in shape than C. planatella. In addition, the comarginal ribs of C. planatella are regular in strength and width, and the space between ribs is also regular; whereas, there tends to be more variation in the sculpture of C. erycina. The two species also have different distributions: C. erycina is found in India and Sri Lanka, and C. planatella is common in Australia and Indonesia (Huber 2010).
The overall shape is elongate, ovate. The anterior, ventral and posterior margins are rounded. The anterior dorsal margin is subconcave, 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 wide, rounded comarginal ribs. There are no ribs on the lunule and escutcheon. The lunule is spear-shaped, defined by a fine, shallow groove and extends 1/3 of the anterior dorsal margin. The umbo is subanterior, and the beaks also point slightly to the anterior. The escutcheon is not well defined.
The exterior is tan, and there are typically two prominent, brown and/or red-brown radial stripes. There may also be tent marks and/or comarginal stripes of the same coloration. The periostracum is red-brown. The interior is white.
The ligament is external, extends half the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth (2a, 2b, 4b), 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 lightly 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 anterior and posterior adductor muscle scars are similar in size and shape. The pallial sinus extends to the middle of the nymph in length and its deepest point forms an acute angle.