« The fact that the family Vesicomyidae comprises two taxonomically distinct groups formed by Vesicomya in one, and the genera of “large” vesicomyids in the other, calls for a formal designation of these groups. Therefore, we propose to distinguish two subfamilies in the family Vesicomyidae: Vesicomyinae Dall & Simpson, 1891 and Pliocardiinae Woodring, 1925. The subfamily Vesicomyinae includes only the genus Vesicomya, which is characterized by small body size (usually less than 10 mm), thin cardinal teeth parallel to the hinge margin, short siphons, lack of pallial sinus, non-reduced gut, two pairs of demibranchs, and an absence of subfilamental tissue in the gills. […]. Genera within the subfamily Pliocardiinae show different sets of characters, however their shared characters include mainly medium or large body size, well developed siphons, reduced gut, and the presence of subfilamental tissue in the gills. » – Krylova & Sahling: “Vesicomyidae (Bivalvia): Current Taxonomy and Distribution”, PLoS ONE 5(4), april 2010, p.5.
 

The genus is monospecific. Shell small, whitish, thin, equivalve, inequilateral; valves convex with the hooks inclined anteriorly; sculpture of thin irregular growth-marks; inside smooth, shiny; pallial sinus and shallow, hardly reaching the third of the shell width.