MorphologyRead full entry
The overall shape is elongate ovate. The anterior margin is slightly more pointed than the posterior, and the posterior margin may be subtuncated. 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 comarginal ribs that become more prominent as the animal grows. The lunule is elongate in shape, extends 3/4 of the anterior dorsal margin, and is defined by a fine shallow groove. The umbo is anterior and the beaks also point slightly to the anterior. The escutcheon is slightly smoother than the area of the flank around it, but otherwise not well defined.
The exterior of the flank is white. There may be rusty-brown comarginal stripes, and the periostracum is dirty gray. The interior is white.
The ligament is external, elongate, 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. There is also one anterior lateral tooth (A2) on the left valve. There are three cardinal teeth on the right valve: 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) on the right valve. The posterior adductor muscle scar is slightly larger and rounder than the anterior adductor muscle scar. The pallial sinus is tapered and extends slightly dorsally; it extends to the center of the nymph in length.