Toxolasma parvus (Barnes, 1823)
Toxolasma parvus, INHS 10134. Otter Creek, LaSalle County, Illinois.
Other common names None.
Key characters Small shell, usually no more than an inch long, elliptical or cylindrical, dark green or brown, with a clothlike texture.
Description Shell small, elliptical or cylindrical, relatively solid, and inflated. Anterior and posterior ends rounded. Umbos inflated and slightly elevated above the hinge line. Beak sculpture consists of five or six distinct angled ridges. Surface of the shell with a clothlike texture, dark green, brown, or dark brown and rayless. Length to 1.5 inches (3.8 cm).
Pseudocardinal teeth thin, elevated, compressed, and serrated; two in the left valve, one or two in the right. Lateral teeth long, thin and straight; two in the left valve, one in the right. Beak cavity moderately deep. Nacre silvery or bluish white and highly iridescent.
Habitat Ponds, lakes, and creeks to large rivers in mud, sand, or fine gravel.
Status Widespread and locally abundant.