Lioconcha fastigiata
Similar to Lioconcha castrensis. Lioconcha fastigiata is more elongate anterio-posteriorly; whereas, L. castrensis is truncated posteriorly.
Similar to Lioconcha hieroglyphica. Lioconcha fastigiata can be distinguished by its more elongate shape and less inflated valves.
Similar to Lioconcha ornata. Lioconcha fastigiata is slightly less inflated, rounder and typically has a continuous tent pattern; whereas, L. ornata is more trigonal in shape and has smaller, finer tent marks on its exterior.
Similar to Lioconcha trimaculata. Lioconcha fastigiata is distinguishable by its truncated posterior margin. L. trimaculata has a more pointed posterior.
The overall shape is trigonal ovate. The posterior margin is short and slightly truncated; the ventral and anterior 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 very fine comarginal ribs at the anterior and posterior areas of the flank. The lunule is not impressed, defined by a fine shallow groove and extends half the anterior dorsal margin; the commissural margin is slightly raised at the center of the lunule, but it is not raised above the shell flank. The umbo is subcentral and the beaks point slightly to the anterior. The escutcheon is not well defined.
The external surface is white and there is typically dark brown tent- or mountain-like patterns. The interior is white, but may have a golden tone descending from the umbonal cavity.
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, and one anterior lateral tooth (A2). The posterior cardinal tooth (4b) is fused with the nymph. 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 lightly bifid. There are also two anterior lateral teeth (A1, A3) on the right valve. There is a fine ridge running parallel to the posterior dorsal margin on both valves. The anterior and posterior adductor muscle scars are similar in area, but the anterior is slightly more elongate. The pallial sinus is absent or very shallow.