Black sandshell

Ligumia recta (Lamarck, 1819)

Black sandshell
Ligumia recta, INHS 11769 and 11722. Mississippi River, Rock Island County, Illinois. Length: 4.6 inches (11.7 cm) for male (top), 4.8 inches (12.2 cm) for female (bottom).

Other common names: Black sand mussel, long John, honest John, sow’s ear, lady’s slipper.

Key characters: Elongate shell, pointed on the posterior end, smooth surface, usually dark brown to black, with a pinkish or purple nacre.

Similar species: Spike, spectaclecaseyellow sandshell.

Description: Shell elongate, solid, and moderately compressed. Anterior end rounded, posterior end pointed in males, saber-shaped in females. Dorsal margin straight, ventral margin straight to curved. Umbos low, only slightly elevated above the hinge line. Beak sculpture, if visible, of two or three indistinct, double-looped bars. Shell smooth and shiny, dark green, brown, or black, with green rays visible on some individuals. Length to 8 inches (20.3 cm).

Black sandshell distribution map 1992

Pseudocardinal teeth triangular, serrated, and divergent; two in the left valve, one in the right, occasionally with a small tooth anteriorly. Lateral teeth long, moderately thin, and straight. Beak cavity shallow. Nacre variable from white, pink, and salmon to deep purple, iridescent posteriorly.

Habitat: Medium to large rivers in riffles or raceways in gravel or firm sand.

Status: Widely distributed but uncommon in much of the Midwest. Threatened in Ohio.

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