The Montezuma Well springsnail (Pyrgulopsis montezumensis) is a species of freshwater snail in the family Hydrobiidae, the mud snails. It is endemic to Montezuma Well, a large sinkhole in Yavapai County, Arizona, in the United States. This snail has an ovate shell measuring no more than 2.7 millimeters tall. The tip of the snout is pigmented. The species is sexually dimorphic.