Obovaria arkansasensis shell description:

There is significant genetic isolation and ecophenotypic plasticity in shell morphology in this species. The following is the shell description for Obovaria jacksoniana “ Shell small; dorsal and ventral margins gently rounded; anterior end uniformly rounded, posterior end sharply rounded in the male and bluntly truncated in the female.  Shell stout, the anterior half thicker than the posterior half; size to 4.3cm; moderately inflated; posterior ridge not prominent.  Beaks broad and low but raised above the hinge line, inequipartite; beak sculpture not discernable on the individuals recovered in this study.  Epidermis light to dark brown; green capillary rays cover the posterior two-thirds of the shell. Left valve has two stout, erect, roughened, triangular pseudocardinal teeth; the lateral teeth are long, roughened and slightly curved.  Right valve has a single erect, columnar, grooved, emarginated pseudocardinal tooth; a small compressed, emarginated tooth can be seen anteriorly; lateral tooth high, roughened and slightly curved.  Interdentum narrow to absent; beak cavity shallow; nacre bluish-white, iridescent posteriorly” (Mather, 2007).