Potamolithus is a genus of small freshwater snails that have an operculum, aquatic gastropod mollusks in the family Tateidae.

Potamolithus was traditionally classified within the Hydrobiidae. However, anatomical study of Potamolithus by Davis & Pons da Silva (1984) showed its relationship with Lithoglyphus, and it is then placed within the family Lithoglyphidae.

The first appearance of the name Potamolithus was in November 1896 as a nomen nudum (a bare name with no description or illustration). The genus was formally defined by Pilsbry in December 1896.

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