Illinois Natural History Survey - University of Illinois

Villosa lienosa (Conrad, 1834)

Little spectaclecase


 

Villosa lienosa, INHS 4844Villosa lienosa, INHS 4844. North Fork Vermilion River, Vermilion County, Illinois. 
Length: 1.8 inches (4.6 cm) for both male (top) and female (bottom).

Other common names Black creek shell.

Key characters Small shell, dark brown with green rays (often obscure), somewhat elongate, with distinct double-looped beak sculpture and pointed or truncated posterior end.Villosa lienosa distribution

Similar species Pondmussel, pondhorn, Texas lilliput.

Description Shell small, slightly elongate, thin to moderately thick, compressed in males and inflated in females. Anterior end rounded, posterior end bluntly pointed (males) or truncated (females). Dorsal margin straight, ventral margin straight to slightly curved. Umbos elevated above the hinge line. Beak sculpture of four to seven distinct, double-looped bars. Periostracum green to dark brown, with green rays (often obscure). Length to 2.5 inches (6.4 cm).

Pseudocardinal teeth relatively small and compressed; two in the left valve, one in the right, with a smaller tooth present anteriorly in some shells. Lateral teeth elongate, thin, and straight. Nacre white or bluish white, occasionally tinged with salmon, iridescent posteriorly.

Habitat Small to medium streams in sand or gravel.

Status Widespread but uncommon in the Ohio River drainage. Endangered in Illinois and Ohio. Species of Special Concern in Indiana.


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