Louisiana Pearlshell

The shell of this freshwater mussel is oblong with moderately full beaks without obvious sculpture. The posterior ridge is low, the anterior end is rounded and the ventral margin is generally straight or slightly curved. The shell surface has uneven growth lines and, if sculptured on the posterior end, it is very faint. The epidermis is brown to blackish and the nacre is white to purple with numerous pits. Adults are about 100 mm (3.9 in) long, 50 mm (2 in) high, and 30 mm (1.2 in) wide.

This species has been collected from only the Bayou Boeuf drainage, Rapides Parish, and the Red River drainage, Grant Parish, Louisiana. Most individuals of the Louisiana pearlshell are found in flowing water at depths ranging from 31 to 61 centimeters (12 to 20 inches) on sand and gravel substrates. Reasons for the decline of the Louisiana Pearlshell include siltation, pollution, and beaver dams which change the water flow in streams.