Common Name

Scientific Name

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Utah Taxonomy

Call (1884) named and described this taxon as Radix ampla var. utahensis, its type locality being "Utah Lake, near Lehi, Utah", and in the type description noted "its relation to Polyrhytis kingii". The type specimens, according to Baker (1911), are in the "Smithsonian Institution, four specimens, No. 31276.

Baker (1911) used the name Galba utahensis for this species, and placed it in the subgenus Polyrhytis, noting: "Polyrhytis is placed tentatively near Stagnicola. The genitalia and radula of utahensis are unknown and until these are published the group cannot be definitely placed." Chamberlin and Jones (1929) discussed this species under the name Polyrhytis utahensis, elevating Polyrhytis to generic status with the caveat: "The exact relationship of this genus cannot be known until the anatomy of utahensis, the only recent and living representative, is worked out." Lowrance (1934) assigned it to the fossil species Stagnicola kingi, and Jones (1940a) and Woolstenhulme (1942a) also used this name for the species. Chamberlin and Roscoe (1948) called the species Stagnicola kingii. Clarke (1991) and other modern authors have assigned the species to Stagnicola utahensis.

Chamberlin and Jones (1929) coined the common name Utah ribbed snail for the species. Clarke (1991) called it the costate Bonneville stagnicola.

Clarke (1991) has questioned whether this taxon is actually specifically distinct from Stagnicola bonnevillensis; however, he stopped short of declaring the two to be synonyms and expressed his view in an unreviewed, unpublished report, and no other malacological authority or author has followed him even in questioning the validity of the two as separate species.

No subspecies have been proposed in this species.

Status in Utah

This species is known, based on living examples, only from Utah Lake, Utah County, and, reportedly, from "Conner's Spring" (= Connor Springs?), Box Elder County (Woolstenhulme 1942a), although the identification of specimens from the latter locality has been questioned (see Clarke 1991). Lowrance (1934) wrote of this species (as Stagnicola kingi): " ... [I]n Utah Lake ... they now live apparently only on the west side along a quarter mile length of shore ...." The species has not been reported as living by any authors since Lowrance (1934).

In the type description Call (1884) remarked: "This is a rare form in Utah Lake, its only locality so far as known." The species survived there until the early 1930s, when Lowrance (1934) remarked: "[I]t is now all but extinct." Recent surveys (e.g., Clarke 1991) have failed to detect living examples.

The cause(s) for the decline and presumed extinction of this species apparently have not been discussed in the literature concerning this species. Since the last living individuals of the species reportedly were found at Utah Lake in the early 1930s (Lowrance 1934), which is approximately the time that certain fishes endemic to Utah Lake are believed to have become extinct, it is plausible that the causes of these extinctions may have been the same. In the case of the fishes, it is believed that the extinctions were the result of extended drought in the early 1930s that drastically lowered water levels in Utah Lake, which even at its fullest is very shallow (only a few feet deep), combined with harsh winters that caused the reduced water in the lake to freeze to (or near) the bottom, probably killing all but the hardiest of organisms living there. Low water levels at this time probably also greatly increased the alkalinity of the lake; that increased alkalinity may have contributed to the demise of this species is suggested by the observation of Lowrance (1934), the last author to report finding this species alive, who noted that he found it only "where springs arising near the present lake level keep the water fresher than it is elsewhere."

Since many examples are known of species presumed to be extinct but later found to be extant, there may be value in continuing to search for living populations of this species in north-central or even northwestern Utah.

Habitats Utilized in Utah

Seemingly the habitat of this species has never been reported. It formerly occurred in Utah Lake and possibly in springs along its shores (see Lowrance 1934). (It was also reported from an isolated spring in northeastern Box Elder County, but the identification of specimens from this locality has been questioned, as discussed above.)


  • Text modified from: Oliver, George V. and William R. Bosworth III. 1999. Rare, imperiled, and recently extinct or extirpated mollusks of Utah[:] a literature review. Publication number 99-29. Utah Division of Wildlife Resources, Salt Lake City. 230 pp.