Page 222 - The Freshwater Mussels of Oklahoma
P. 222

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.












                                                            221
   217   218   219   220   221   222   223   224   225   226   227