Lioconcha schioettei
Shell ovate-trigonal, with right and left valves of equal size and shape (equivalve); umbones subcentral, nearer to and pointing to the anterior end (prosogyrous); antero-dorsal margin straight to externally concave, transitioning smoothly to the rounded anterior margin; anterior, ventral and postero-dorsal margins externally convex; posterior margin varying from rounded to subtruncate; lunule faintly marked by a shallow groove, flush with the general surface of the shell throughout, meeting the commissural plane halfway between the beaks and the anterior end of the shell; escutcheon indistinct; shell exterior white with yellowish to brown rays of color and chevron patterns (tent marks), commonly covered by a white, flaky, dehiscent coat (comprised of long, very fine calcified needles, only visible under a microscope); external sculpture of low, irregular commarginal ridges, which may be present throughout the shell flank or restricted to the anterior and posterior ends; internal surface of the shell usually with a yellowish blotch in the umbonal cavity and a ray or blotch of purple pigment posteriorly; internal shell margins without obvious crenulation; pallial sinus very shallow; ligament external, supported by a nymphal ridge in each valve; hinge of the right valve with two anterior lateral teeth (A1 and A3), three cardinals (3a, 1 and 3b) and a faint posterior lateral (P1); only the posteior cardinal (3b) is subdivided distally (bifid); socket between laterals A1 and A3 confluent with socket between anterior and middle cardinals (3a and 1); hinge of the left valve with one anterior lateral tooth (A2), three cardinal teeth (2a, 2b and 4b), and a faint posterior lateral (P2); all teeth in the left valve entire (not bifid); lateral tooth A2 separate from anterior cardinal (2a); cardinals 2a and 2b dorsally united.