Henderson and Daniels (1917) referred to this species in Utah as Planorbis exacuous. Chamberlin and Jones (1929) called it, in Utah, Menetus exacuous, and applied to it the common name the keeled, discoid snail, and they considered Call's (1884) record of Menetus opercularis to be this species. Chamberlin and Berry (1930), Jones (1940a), and Chamberlin and Roscoe (1948) all referred to the species in Utah as Menetus exacuous, Chamberlin and Roscoe (1948) having indicated that it was in the subgenus Promenetus.
No subspecies are recognized in this species.
Status in Utah
About 7 or 8 historical occurrences of this species have been reported in Utah, all reports being from the north-central part of the state (Cache, Weber, Davis, Salt Lake, extreme western Summit, and Utah counties [Call 1884, Henderson and Daniels 1917, Chamberlin and Jones 1929, Jones 1940a]) except for one documented locality in south-central Utah (Sevier County [Chamberlin and Jones 1929, Chamberlin and Berry 1930]).
Jones (1940a) had records of 1 specimen of this species from each of 5 Utah localities, which suggests that the species was found to be rare in the places where it occurs in Utah. Chamberlin and Jones (1929), writing of this species, commented: "Comparatively rare in Utah Lake." The species is now considered extirpated from Utah Lake.
The extirpation of this species from Utah Lake is indicative of the threatened status of this species in Utah. All but one of the reported Utah localities for the species are in the portion of the state that is undergoing the most rapid and extensive development (i.e., north-central Utah). This is resulting in the loss and degradation of natural habitats, especially wetlands, which is almost certainly a threat to this aquatic gastropod. Even the 1 reported Utah occurrence of this species that is not in north-central Utah is from a locality, Fish Lake, that, though not obviously impacted by human activities, has experienced within this century the extinction of an aquatic gastropod species that was formerly endemic to this one water body (the Fish Lake physa, Physella microstrata), which suggests that other native aquatic mollusks, including this species may not be secure in Fish Lake.
Though the population trend of this species in Utah is not known, the disappearance of the species from Utah Lake suggests that it is declining in this state.
Inventory is needed at the sites from which this species has been reported historically as well as elsewhere in Utah to determine its current status in the state.
Habitats Utilized in Utah
Most Utah records of this species have been from lakes (see, for example, Call 1884, Chamberlin and Jones 1929, Jones 1940a), though it has also been collected from a reservoir in Utah (Henderson and Daniels 1917).