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Description
The shell of the pimpleback is relatively thick and round to squarish in shape. Most shells have tubercles along the posterior 2/3 of the shell; although, some individuals may lack this feature entirely or display only a few tubercles. The periostracum ranges from yellow or golden brown but darkens to brown or black with age. A green ray may extend from the umbo to the ventral margin. The nacre is white with iridescence in the posterior half. There are two pseudocardinal teeth in the left valve and one in the right. The lateral teeth follow the same pattern. (Parmalee and Bogan 1998).

Distribution
This species' range includes waterways throughout "the entire Mississippi River drainage" (Parmalee and Bogan 1998). Its range-wide conservation status is currently stable (Williams et al. 1993). The pimpleback is no longer found in North Carolina.

Habitat Preferences
The pimpleback is a habitat generalist, tolerating both reservoir and riverine conditions (Parmalee and Bogan 1998).

Life History
This species is "tachytictic, being gravid from about mid-June to mid-August" (Parmalee and Bogan 1998). Fuller (1974) identified fish hosts including the shovelnose sturgeon, black bullhead, brown bullhead, channel catfish, flathead catfish, and white crappie.