AIM

Ligumia recta (Lamarck)

Black sandshell

Recognition

The shell is solid, dark colored, elongate, and it has well developed teeth and pinkish nacre. Males are more pointed posteriorly than the females. The ventral edge is convex. The usual size in 120 to 150 mm. It is superficially similar to Margaritifera falcata, which is smaller, thinner, and has weaker teeth, purple nacre and occurs in cooler trout rivers and streams much further upstream.

Summary

This species may be a newcomer to Montana. It seems too big, widespread and common to have been missed by early workers. It is also absent from Native American sites where Lampsilis siliquoidea shells are common. The known fish hosts include the native sauger and introduced centrarchids. The sauger is common in the middle and lower Yellowstone drainage, but Ligumia is not. Even if it is introduced, there is no obvious sign that it has has negative impacts on other species here so it might as well be welcomed as enriching our mussel impoverished rivers.

Distribution

In the Missouri, Musselshell and Milk Rivers, possibly spreading from a Fort Peck Reservoir introduction. Outside of Montana this is a widespread species in the central and eastern parts of the continent. It is also covered in the Field Guide to the Freshwater Mussels of the Midwest.

17 DEC 1995, updated on 12 JAN 1996 D.L. Gustafson