Lamelliconcha callicomata
Similar to Lamelliconcha alternata. Lamelliconcha callicomata is more elongate, ovate in shape and has less prominent umbones; L. alternata is trigonal ovate. L. callicomata has more prominent, lamellar comarginal ribs than L. alternata, and L. callicomata lacks the brown coloration on the lunule and escutcheon typically found in L. alternata.
Similar to Lamelliconcha tortuosa. Lamelliconcha callicomata is distinguishable by its more prominent, lamellar comarginal ribs; L. tortuosa has weaker, more rounded ribs that are not lamellar. In addition, some ribs of L. tortuosa split, resulting in a higher number of ribs at the posterior than the anterior; this characteristic is not found in L. callicomata. L. callicomata also has weaker umbones than L. tortuosa, giving it a slightly more ovate, less trigonal shape.
The overall shape is elongate, ovate. The anterior and posterior margins are both subtruncated, and the ventral margin is rounded. There is a slight sinuousity of the margin at the confluence of the posterior and ventral margins. The anterior dorsal margin is subconcave, and the posterior dorsal margin is subconvex. The anterior half of the flank if slightly more inflated than the posterior half. The valves are equal in size and shape (equivalve), and there is no gape when they are closed. Sculpture consists of growth lines and erect comarginal ribs that become more lamellar ventrally, anteriorly and posteriorly. The ribs may alternate in strength, or there may be one stronger rib for every 3-4 ribs. The lunule and escutcheon lack ribs and are smoother than the rest of the flank. The lunule is lightly impressed, defined by a fine shallow groove and extends 1/5 of the anterior dorsal margin. The umbo is anterior and the beaks also point slightly to the anterior. The escutcheon is lightly raised, extends half the posterior dorsal margin and is defined by a fine, shallow groove.
The exterior is white and there may be some yellow coloration near the umbo or along the comarginal ribs. The interior is white, and there may be some light yellow coloration in the umbonal cavity, descending ventrally.
The ligament is external, extends 1/3 to half the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth. The anterior tooth (2a) is weak and not bifid, the central tooth (2b) is robust and may be grooved or lightly bifid, and the posterior tooth (4b) is not bifid and fused with the nymph. The anterior (2a) and central (2b) teeth are fused dorsally, creating an inverted "v" shape. 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) on the right valve, as well as a fine ridge running parallel to the posterior dorsal margin. The posterior adductor muscle scar is slightly larger and rounder than the anterior adductor muscle scar. The pallial sinus is deep, rounded and extends to the central tooth in length.