Lioconcha gordoni
The overall shape is trigonal ovate. The posterior, 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 rounded comarginal ribs that become wider as the animal grows. There are no ribs on the lunule. The lunule is rounded, defined by a fine, shallow groove and extends 1/4 of the anterior dorsal margin. The umbo is subanterior and the beaks also point slightly to the anterior. The escutcheon is not well defined.
The exterior is white or cream with light brown zig-zag patterns. The patterns may overlap, creating areas of darker pigmentation. There may be dark coloration at the posterior dorsal margin. The beaks may be purple. The interior is white with dark purple coloration in the umbonal cavity, descending ventrally and fading into a light brown color near the pallial line.
The ligament is external but slightly sunken, extends 1/4 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. The anterior (2a) and central (2b) teeth are joined dorsally, forming an inverted "v" shape. The posterior tooth (4b) is not 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 lightly bifid. There are also two anterior lateral teeth (A1, A3) on the right valve, as well as a fine ridge that runs parallel to the posterior dorsal margin. The anterior and posterior adductor muscle scars are similar in area, but the posterior is slightly more round. The pallial sinus is very shallow.