Page 237 - The Freshwater Mussels of Oklahoma

Descripton:
“Shell small in size, seldom exceeding 40 mm in length. Outline ovate, or short
obovate. Valves subinflated, solid. Anterior end regularly rounded; posterior end
somewhat pointed. Ventral margin regularly curved. Dorsal margin rather rounded,
forming a more or less distinct angle with the obliquely descending posterior margin.
Posterior ridge, low, almost double, ending a slight biangulation below the medial line.
Hinge ligament short. Umbos not much swollen, slightly projected above the hinge line,
the sculpture not observed, located in the anterior third of the shell. Surface of the shell
with irregularly concentrical striations. Periostracum dull to subshiny, yellowish to
brownish, usually with fine green rays over the entire surface.
Left valve with two rather heavy, triangular, pseudocardinal teeth of about equal
size, and two short lateral teeth. Right valve with two pseudocardinals, the posterior one
chunky, the more anterior tooth vestigial. No interdentum. One lateral tooth. Anterior
adductor muscle scars well impressed, posterior ones faint. Pallial line visible anteriorly.
Nacre silvery white, bluish, iridescent posteriorly.
Male shells are somewhat pointed. Female shells are more broadly rounded, and
truncated below the medial line. In mature females there is a distinct “constriction” in the
middle of this truncation” (Johnson, 1980).
Comments:
There has been considerable confusion regarding this species in Oklahoma.
Considerable similarity occurs between this species and O. jacksoniana. Currently I
consider this species to be confined to Arkansas and all reports of V. arkansasensis
should probably be referred to as O. jasksoniana.

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