Toxolasma texasensis (Lea, 1857)
Other common names: None.
Key characters: Small shell, pointed or truncated on the posterior end, and greenish brown or black with a clothlike texture.
Description: Shell elongate, thin to relatively solid, and moderately inflated. Anterior end rounded, posterior end pointed (males) or truncated (females). Umbos even with or only slightly elevated above the hinge line. Beak sculpture of five or six strong angular ridges. Periostracum greenish brown to black with clothlike texture. Length to 2.5 inches (6.4 cm).
Pseudocardinal teeth relatively thin and compressed, elevated and serrated; two in the left valve, one in the right. Lateral teeth long, straight or curved; two in the left valve, one in the right. Beak cavity shallow. Nacre white, occasionally tinged with salmon in the beak cavity and center of the shell.
Habitat: Small to medium streams or sloughs in mud or sand in slow-flowing water.
Status: Essentially a southern species that is rare in the Midwest.