Mactrellona iheringi (Dall, 1897)

Reaching up to 5.5 cm long, the Mactrellona iheringi species are inequilateral (their beaks prominent, pointed and anterior to midline), with slightly more pointed anteriorly. The shell itself is thin, fragile and smooth except for fine concentric growth rings that become rougher both anteriorly and posteriorly. They are a white grey, yellow-brown, or cream in color and the interior is the same color as the exterior. They are known to lack the posterior radial ridge of the Mulinia cleryana, Mactra petitii and Mactra surinamensis shells. The left valve bears one anterior lateral, one posterior lateral and three cardinal teeth, two of the latter teeth forming the characteristic V-shape. The third cardinal tooth is weak and sometimes broken. The right valve bears two cardinals, two anterior and two posterior laterals. The ligament is both external and internal: the chondrophore (containing the internal portion) being is set off from the rest of the ligament by a thin plate or septum. The pallial sinus is fairly well developed and stretches to the midline. Single valves are common but double valves are more rare.