Pyrgulopsis is a genus of freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Hydrobiidae.
Generic characters of the genus Pyrgulopsis are: the shell is minute, conically turreted, somewhat elongated, imperforate and unicarinate. The apex is acute. The aperture is ovate. The edge of the aperture, called the peritreme, is continuous.[1] The operculum is ovate, thin, corneous and spiral, with polar point well forward and approximating the columella.[1]
The jaw is thin and membranaceous.[1] The radula is odontophore, with teeth are arranged in transverse rows, according to the formula 3 + 1 + 3. Formula for denticles of rhachidian: 4 + 1 + 4⁄1 + 1.[1]
The distribution of the genus Pyrgulopsis includes Western and South-western United States.[1] Snails of species in the genus Pyrgulopsis occur in fresh water and in brackish water.[1]
Pyrgulopsis is the largest genus of freshwater gastropods in the North America. In 2014, 139 species were recognized in this genus.[4]
Eastern North American species of Pyrgulopsis[20] are considered to be in separate genus Marstonia according to the Thompson and Hershler (2002).[21]