Illinois Natural History Survey - University of Illinois

Fusconaia flava (Rafinesque, 1820)

Wabash pigtoe


 Fusconaia flava, INHS 11802
Fusconaia flava, INHS 11802. Mississippi River, Buffalo County, Wisconsin. 
Length: 2.4 inches (6.1 cm).

Other common namesPigtoe.

Key characters Triangular shell with a shallow sulcus usually present on the side, rough clothlike periostracum, deep beak cavity.


Similar species All other pigtoes (Fusconaia and Pleurobema).

Description Shell highly variable, moderately thick, triangular, and compressed (creeks and small rivers) to inflated (large rivers). Anterior end rounded, posterior end bluntly pointed. Dorsal margin straight, ventral margin curved anteriorly and straight or slightly arched posteriorly. Umbos low to moderately elevated and inflated. Beak sculpture of a few weak ridges apparent only in very small shells. A wide, shallow depression or sulcus usually present. Shell with a clothlike texture, yellowish brown, with faint green rays visible in young individuals, becoming chestnut or dark brown in older shells. Length to 3 inches (7.6 cm). Fusconaia flava distribution

Pseudocardinal teeth well developed, rough; two in the left valve, one in the right. Lateral teeth straight or slightly curved, serrated; two in the left valve, one in the right, occasionally with a second smaller lateral tooth. Beak cavity deep. Nacre white, or tinged with salmon, iridescent posteriorly.

Habitat Creeks to large rivers in mud, sand, or gravel.

Status Widespread and common.

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