Actinonaias ligamentina (Lamarck, 1819)
Actinonaias ligamentina, INHS 13303. Iroquois River, Kankakee County, Illinois.
Other common names Grass mucket, brass mucket, steamboat mucket.
Key charactersRelatively large, oblong, thick shell, yellowish brown, with green rays and a relatively shallow beak cavity.
Description Shell large, elliptical or oblong, thick, usually heavy, and compressed to moderately inflated. Anterior end rounded, posterior end bluntly pointed. Umbos slightly elevated above the hinge line. Beak sculpture of a few fine, double-looped ridges, usually visible only in young shells. Periostracum smooth, yellowish brown, with numerous green rays. Large shells dark brown with faint green rays or rayless. Length to 7 inches (17.8 cm).
Pseudocardinal teeth large, slightly elevated and serrated; two in the left valve, one in the right. Lateral teeth straight to slightly curved, thin, and moderately long. Beak cavity shallow to moderately deep. Nacre white, occasionally tinged with pink or salmon, iridescent posteriorly.
Habitat Medium to large rivers in gravel or mixed sand and gravel.
Status Widespread and locally abundant. Extirpated from Ohio.