Sunetta kirai
The overall shape is ovate with rounded anterior and ventral margins. The posterior margin is lightly truncated. The posterior half of the flank is slightly more inflated than the anterior, but overall the valves are rather compressed. The valves are the same shape and size (equivalve), and there is no gape when the valves are closed. Sculpture consists of growth lines only. The lunule extends up to half the anterior dorsal margin, and the commisural margin is raised at its center. The umbones are slightly anterior. The escutcheon is sunken.
The external color is white with light brown coloration in comarginal stripes, radial stripes and/or tent marks. The brown coloration may deepen as the animal grows. The lunule is typically dark brown or purple. The interior color is white. There may be purple coloration in the umbonal cavity, stretching ventrally and posteriorly. The purple coloration may also just be concentrated posteriorly.
The ligament is external, spans 1/3 of the posterior dorsal margin and is supported by nymphal ridges. On the left valve, there are three cardinal teeth. The cardinal teeth (2a, 2b, 4b) are not bifid, and the posterior tooth (4b) is 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 teeth (3a, 1, 3b) are not bifid, and posterior (3b) tooth is slightly rugose. There are two anterior lateral teeth (A1, A3) on the right valve. There may be a weak ridge running parallel to the posterior dorsal margin on both valves, but more commonly on the right valve. There are antimarginal crenulations along the internal margins. The anterior and posterior adductor scars are similar in size and shape. The pallial sinus is pointed and extends to the posterior end of the nymph in length.