Pyganodon grandis shell description:

“Shell long ovate, subrhomboid or subelliptical, generally rather strong, subinflated, inequilateral: beaks usually full and more or less elevated above the dorsal line, their sculpture consisting of a few strong, irregular, broken ridges, which are sharply, doubly looped, the bases of the loops nearly or quite nodulous; posterior ridge full, frequently more or less double and ending behind in a rounded or feebly biangulate point at the median line; post-dorsal wing low, obliterated in old specimens; upper anterior edge either slightly angled or rounded; base line curved; epidermis greenish-brown or brownish-green, rarely faintly rayed, but showing about three broad, dark rays on the posterior slope; beak cavities varying from shallow to moderately deep, not compressed; nacre bluish-white, rarely tinted purple, sometimes a little thickened in front ”(Simpson, 2014; Mather, 2007).