Callista planatella
Similar to Callista erycina. Callista planatella has a slightly more elongate shape than C. erycina. 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).
Similar to Callista grata. Callista planatella has more prominent comarginal ribs and the exterior of its valves are more glossy than those of C. planatella. In addition, C. planatella is distinguishable by the lack of internal purple pigmentation; whereas, C. grata has internal purple coloration at its posterior margin. The two species also have different distributions: C. grata is found in China and the Philippines, and C. planatella is found in Indonesia and Australia (Huber 2010).
Similar to Callista spuma. Callista planatella has wider comarginal ribs that are slightly more prominent than those of C. spuma. In addition, C. planatella has a straighter, less convex posterior dorsal margin, and its lunule is less elongate. C. planatella lacks the interior purple coloration at the posterior margin that is typically found in C. spuma.
The overall shape is elongate, ovate. The anterior, ventral and posterior margins are rounded. 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 wide, rounded comarginal ribs. There are no ribs on the lunule; it is spear-shaped, defined by a fine, shallow groove, and extends half of the anterior dorsal margin. The commissural margin may be lightly raised at the center of the lunule, but it does not extend above the surface of the flank. The umbo is subanterior and the beaks point slightly to the anterior. The escutcheon is not well defined.
The exterior is white or tan. There are typically brown radial stripes and also intermittent brown rectangles along radial lines and/or along radial stripes. Individual stripes may be variable (discontinuous, broken up, varying in width) across the flank. The brown coloration deepens at the anterior and posterior of the flank. The interior is white.
The ligament is external, extends 1/3 of 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 weakly bifid. There are two anterior lateral teeth (A1, A3) on the right valve, as well as a fine, weak ridge running 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 middle of the nymph in length and forms an acute angle at its deepest point.