Pitar pilula
The overall shape is trigonal ovate. The posterior margin is subtruncated, and the anterior and ventral 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, and there is no gape when they are closed. Sculpture consists of growth lines; some of the growth lines may be slightly more prominent, especially near the ventral margin, forming weak comarginal ribs. The lunule is large and tear-drop shaped, is defined by a fine, shallow groove and extends 3/4 of the anterior dorsal margin. The umbo is central and the beaks point slightly to the anterior. The escutcheon is not well defined.
The exterior is white or tan with a light brown periostracum. There may be some faint brown or purple coloration along the comarginal ribs. 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, 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 that runs parallel to the posterior dorsal margin. The anterior and posterior adductor muscle scars are similar in size and shape. The pallial sinus is rounded and extends to the posterior end of the nymph in length.