Cyclonaias pustulosa,[2] the pimpleback,[1] is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.

This species is native to North America, where it is widespread[1][3] and common.

[1] It has possibly been extirpated from New York, however, and populations in Pennsylvania are critically imperiled, according to NatureServe.

[1] The species was formerly classified within the genus Quadrula, and in 2012 it was moved to Rotundaria based on genetic evidence.

[4] This Unionidae-related article is a stub.