Pitar laetus
Similar to Pitar curnowae. Pitar laetus is distinguishable by its less inflated valves and less prominent umbones. In addition, the exterior of P. laetus is much smoother because it has weaker sculpture.
Similar to Pitar potteri. Pitar laetus is less elongate in shape, has less anterior umbones, rounder margins, and characteristically has dark coloration at the posterior margin that is not found in P. potteri.
Similar to Pitarina kurodai. Pitar laetus is distinguishable by its weaker umbones, rounder posterior margin and the smooth central area of the flank, as well as its dark coloration at the interior and exterior posterior margin that is not found in P. kurodai. In addition, P. laetus lacks the strong sinuosity at the posterior ventral margin that is found in P. kurodai.
The overall shape is trigonal ovate. The anterior margin is lightly pointed, and the ventral and posterior margins are rounded. The anterior dorsal margin is nearly straight and the posterior dorsal margin is subconvex. The valves are inflated, equal in size and shape (equivalve), and there is no gape when they are closed. Sculpture consists of growth lines and very fine, dense comarginal ribs posteriorly. There may be a light sinuosity at the confluence of the posterior and central areas of the flank. The lunule is rounded, extends 3/4 of the anterior dorsal margin and is defined by a fine shallow groove. The umbones are prominent and subanterior, and the beaks also point slightly to the anterior. The escutcheon is not well defined.
The exterior is white with a dirty gray periostracum. There is typically dark brown-purple coloration restricted to the posterior area of the flank, but the pigmentation may cover the area near the ventral margin as well. The interior is white with purple coloration at the posterior.
The ligament is external, but slightly sunken; it extends half the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth. The anterior (2a) and central (2b) teeth may be shallowly grooved or rugose; they are joined near the hinge plate, forming an inverted "V" shape. The posterior tooth (4b) is not bifid. 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 also two anterior lateral teeth (A1, A3) and a weak ridge running parallel to the posterior dorsal margin on the right valve. The anterior and posterior adductor muscle scars are similar in area, and the anterior is more elongate than the posterior. The pallial sinus is rounded and extends to the center of the nymph in length.
Pitar laetus is found in the Indo Pacific and Australia.