Clench (1925) named and described this taxon from Utah Lake, placing it in the genus Physa as a subspecies: Physa lordi utahensis. In a letter to Ralph Chamberlin, however, Clench stated (as quoted in Chamberlin and Jones 1929): "I have since [the time of the type description] considered this [taxon] as rating full specific status." Chamberlin and Jones (1929) thus arranged it as a species, placing it, however, in the genus Physella. Henderson (1936)--and later Jones (1940a, Chamberlin and Roscoe (1948), and Russell (1971)--referred to the species as Physa utahensis.
Chamberlin and Jones (1929) called this species the Utah sinistral pond snail. Clarke (1991) applied to it the common name Utah Lake physella.
No subspecies have been proposed in this species.
Status in Utah
Two extant occurrences of this species in Utah are known, both in northeastern Box Elder County. The species inhabits three pools "located near Utah Hwy. 83, 14.3, 14.7, and 16.9 road miles W of Corrine, Cache [sic: Box Elder] County", and "Bar M Spring, Locomotor [sic: Locomotive] Springs area", also in Box Elder County (Clarke 1991).
Historically the species inhabited Utah Lake and associated springs (Chamberlin and Jones 1929, Jones 1940a), where it is now extirpated (Clarke 1991). Henderson (1936) reported this species from "a spring seven miles south of Junction, [Piute or Garfield County], Utah", which must be regarded as a historical occurrence, probably extirpated.
Russell (1971) reported the species from 4 of the springs making up the spring complex at Fish Springs, Juab County. It is unknown whether, but somewhat doubtful that, the species is extant at Fish Springs; moreover, Taylor (1986) seemed to doubt Russell's (1971) identification of this species at Fish Springs.
In the Museum of Zoology, University of Michigan, there reportedly are 4 lots of specimens collected live prior to 1950 in Utah (Clarke 1991). One of these lots is from Redden Spring, extreme southwestern Tooele County, the other 3 are accompanied by only "inadequate locality data" but may be from the same locations as those reported by Clarke (1991) from north-central and northeastern Box Elder County.
It is possible that this species could be found in southeastern Utah in northeastern San Juan County in the Dolores River drainage. There are two collections of this species from Montrose County, Colorado, near the San Juan County, Utah, border. One of these lots is catalogue number 4978 in the University of Colorado Museum, from West Paradox Valley "in the Dolores River drainages" (Wu 1989). The other is in the Museum of Zoology, University of Michigan, "live-collected prior to 1950", from "Paradox Valley" (Clarke 1991).
Clarke (1991), "based on apparent population densities and areas occuppied [sic] in June, 1990", estimated populations of more than 2,100,000 individuals at one Utah site of occurrence (combining three associated smaller sites) and more than 100,000 at the other Utah site of occurrence. Despite these large population estimates, the pools inhabited are small (of the three combined as one occurrence, each is "between about 1/4 and 3/4 acre in area", and the other occurrence is in a pool somewhat larger). Furthermore, Clarke at times seems to overestimate populations (see account of Oreohelix eurekensis). In view of the small number of the pools inhabited and their small sizes, the abundance of this species, especially relative to other organisms, must be considered very low.
Potential threats to the known extant occurrences include introductions of fishes and dewatering. The cause of the loss of the presumably large population in or near Utah Lake is not known.
Current population trend in Utah is not known, but it is certain that the population has been radically reduced during the 20th century.
Inventory of several of the historical localities, especially Redden Spring, Tooele County, and springs at Fish Springs National Wildlife Refuge, Juab County, as well as search for the spring south of Junction near the Piute-Garfield County line, is needed, along with more extensive prospective surveys in northern and northeastern Box Elder County. This species should also be sought in eastern or northeastern San Juan County (e.g., in the Dolores River drainage and elsewhere).
Habitats Utilized in Utah
Clarke (1991) reported: "The 4 Utah sites which contained P. utahensis are all spring-fed pools. ... Each [of three of the sites] is a shallow pool between about 1/4 and 3/4 acre in area, each [of three] is well vegetated, andthe [sic] substrate at each [of three] was of mud, sand, gravel, and/or rocks. ... [The fourth site] was an unusual, large, and very shallow pool virtually paved with flat rocks and choked with watercress."
Russell (1971), reporting this species from 4 of the springs in the Fish Springs complex, wrote: "This species was not seen alive in any of the marshes or canals but is known only from springs." Taylor (1986), however, seems to have doubted Russell's (1971) identification of this species at Fish Springs.