This species has been allocated to various genera. Works dealing with Utah have assigned it to the genera Melania (see Yarrow 1875), Paludestrina (see Chamberlin and Jones 1929, Jones 1940a), Hydrobia (see Chamberlin and Roscoe 1948), and more recently Tryonia (see Russell 1971, Hershler no date).
A very old record of this species from Utah (Tryon in Ruschenberger 1873) also placed it in the genus Tryonia, as it is currently arranged, but tentatively assigned it to species as "probably T[ryonia] exigua", "of which Melania protea, Gould, is a synonym". Yarrow (1875) reported that Tryon had written to him of a specimen of this species collected in Utah, which Yarrow listed as "?Tryonia exigua", noting: "Mr. Tryon informs me this is probably T. exigua, Stimp., or else a new species. Unfortunately, not enough specimens were secured to establish the latter."
Chamberlin and Jones (1929) used the common name the cornucopia snail for the species.
Seemingly no subspecies have been proposed in this species.
Status in Utah
There are 9 known occurrences of this species in Utah. Chamberlin and Jones (1929) wrote, with regard to Utah: "Range.--Great Basin ...." Although Russell (1971) stated that this species occurs in "southern Utah", all known Utah localities are from the 3 adjacent counties Tooele, Utah, and Juab in north-central and west-central Utah: Juab County (6 sites at 1 locality, Russell 1971, also Hershler, no date), Tooele County (2 localities, Chamberlin and Jones 1929; 1 locality [probably the same as one in Chamberlin and Jones 1929], Jones 1940a; 3 localities, Hershler no date), Utah County (1 locality, Jones 1940a). These localities correspond well with Chamberlin and Jones' (1929) assertion that the species occurs in Utah within the Great Basin.
Tryon (in Yarrow 1875) reported an example of this species from the "shores of Sevier Lake [Millard County]". Since this specimen would have been drift material, of unknown age (possibly prehistoric, hundreds or even thousands of years old) and of unknown origin (undoubtedly washed into Sevier Lake and possibly from almost anywhere in the Sevier River drainage, which takes in parts of at least 4 counties), the record is of little value.
Chamberlin and Jones (1929), writing of this species in Utah, stated that it is "rare". Hershler (no date) reported the species from 4 localities in Utah; for 2 of these 4 localities he indicated abundance of this species, in both cases stating it was "scarce". The few documented Utah occurrences and highly restricted habitat of this species suggest that it is of rather low abundance in Utah relative to other organisms.
Hershler (no date) reported this species at 4 localities in Utah; he considered disturbance to be slight at 2 of these sites, moderate at 1, and high at 1. Impacts noted by Hershler (no date) at these locations included recreational activities, the presence of livestock (trampling), and alteration of the aquatic habitat (one spring had been dug out). He also noted the presence of fish at 2 of the sites. Population trend of this species in Utah is not known.
Inventory elsewhere in the Great Basin portion of Utah is needed.
Habitats Utilized in Utah
Russell (1971) wrote: "Occurrence at Fish Springs [Juab County, Utah]: This species is generally found living in springs and spring outflows." Hershler (no date) provided habitat details for 4 Utah localities: Three of the sites were limnocrenes; 1 was a rheocrene. Elevations were 4,320 to 4,500 ft. Temperatures were 22, 26, 26, and 28 degrees C, all of which are rather warm temperatures for springs. Conductivities were 3,100, 9,300, 9,500, and 34,800 micromhos/cm; even the lowest of these (3,100 micromhos/cm) is high, and the highest (34,800 micromhos/cm) is extremely high.