Leptodea leptodon (Rafinesque, 1820)
Other common names: Narrow papershell.
Key characters: A thin, elongate, compressed shell, yellowish green or brown, with fine green rays, pointed posterior end, poorly developed pseudocardinal teeth, and very fine lateral teeth.
Similar species: Fragile papershell.
Description: Shell relatively small, elongate, thin, and compressed. Anterior end rounded, posterior end pointed. Dorsal margin straight, ventral margin straight to broadly curved. Umbos small and low, about even with the hinge line. Beak sculpture, if visible, of four or five double-looped ridges. Shell smooth, yellowish green or brown, with numerous faint green rays. Length to 4 inches (10.2 cm).
Pseudocardinal teeth reduced to a small thickened ridge. Lateral teeth moderately long; two low, indistinct lateral teeth in left valve, one fine tooth in the right. Beak cavity very shallow or absent. Nacre pinkish white or light purple and highly iridescent.
Habitat: Large rivers in mud.
Status: Federal Candidate (Category 2). Extirpated from Ohio. Likely extirpated from Illinois, Iowa, and Indiana. Rare in Missouri. Species of Special Concern in Michigan.