Page 222 - The Freshwater Mussels of Oklahoma

Description:
“Shell:
Generally oval, occasionally subrectangular; some misshaped shells may be
shortened posteriorly (resemble in outline marine quahog or hard clam, Mercenaria);
moderately thick, solid; occasionally slightly winged; somewhat inflated; dorsal margin
slightly curved to nearly straight, anteriorly rounded, ventrally rounded to almost straight,
posteriorly slightly rounded, weakly pointed posterior-ventrally; beaks raised above hinge
line, beak cavities relatively deep; posterior ridge broadly rounded; shell surface
generally smooth except for concentric growth rings.

Shell Teeth:
Left valve with two pseudocardinal teeth pointed to round pointed, striated,
anterior tooth sometimes strongly squared to round pointed, and larger than posterior
tooth; right valve has two pseudocardinal teeth (or one pseudocardinal tooth and a large
anterior denticle), anterior tooth is often squared and strongly striated, posterior tooth
broadly rounded and striated; lateral teeth moderately long, very slightly curved and
lightly striated, elevated, leaf-like, compressed (posteriorly-shortened individuals may
show more curvature in lateral teeth); among the two teeth in the left valve, the ventral
lateral tooth often slightly shorter than the dorsal tooth.

External Color:
Dull or shiny; reddish-brown to dark brown or black, grayish in some individuals;
juveniles may show very faint, thin (rarely broad) darker rays, some populations may
retain rays into early adulthood (atypical of most).

Internal Color:
Most frequently purple, but may be white, pink, salmon, or orange, rarely a
combination of two or more colors; small juveniles often exhibit white nacre with darker
coloration developing gradually” (Howells, Neck and Murray, 1996).
Comments:
This species is characteristic of much of central and south Texas and approaches
Oklahoma in the Brazos and Colorado River drainages. One specimen was collected in
the Oklahoma portion of Lake Texoma (Mather, 1989) and undoubtedly represents an
introduction into the lake. It is uncertain whether this was an isolated specimen or an
established population.

Red River System:
Bryan County: Lake Texoma at Lakeside.

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