Classification: State Threatened
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Isaac Lea described the mountain creekshell in 1838. There is sexual dimorphism in shell shape. The ventral margin is curved in the male. In the female, the ventral margin is straight with a distinct swelling along the posterio-ventral margin to accommodate the marsupium. Older females may have a constriction along the posterio-ventral margin associated with this swelling. The dorsal margin may be slightly curved. There are two short pseudocardinal teeth in the left valve, and one in the right. The lateral teeth are thin and slightly curved, following the dorsal margin. The periostracum may be olive or golden brown to black. If present, rays are narrow and indistinct. The nacre may range from purples to copper in color. (Parmalee and Bogan 1998).
This species is bradytictic; females may be gravid from September to May (Parmalee and Bogan 1998, Ortmann 1921). Several species of sculpin (banded, black, mottled, and slimy) have been identified as fish hosts (Watters 1994).
General Life History For Mussels