Henderson and Daniels (1917), in the only report of this species from Utah, used for it the name Lymnaea traskii. Chamberlin and Jones (1929), summarizing Henderson and Daniels' (1917) Utah findings, called the species Stagnicola traskii. Chamberlin and Roscoe (1948) listed it for this state as Stagnicola traski, the name currently applied to the species.
No subspecies are recognized in this species.
Status in Utah
Baker (1911) summarized all known localities for this species, these being about 4 localities in California and 1 each in Wyoming and Alberta, and commented: "A careful search [for this species] will doubtless fill the vacant territory between Wyoming, California and Alberta." Two somewhat questionable historical occurrences of this species in Utah have been reported. Henderson and Daniels (1917), the only authors who have reported finding this species in Utah, provided the two locality records for this state, both in north-central Utah: below the mouth of Ogden Canyon (Weber County) and the west side of Garfield (Tooele County). There remains, however, some doubt whether this species actually occurs or ever occurred in Utah. Chamberlin and Jones (1929) wrote: "The occurrence of typical traskii in Utah is doubtful. ... Henderson now refers specimens ... listed on authority of himself and Daniels to nuttalliana." Despite this statement, almost 20 years later Chamberlin and Roscoe (1948) continued to list Stagnicola traski as occurring in Utah and did not list Stagnicola nuttalliana. (Stagnicola nuttalliana, incidentally, is no longer a recognized species.) Thus it appears that Chamberlin reversed his earlier opinion and accepted Henderson and Daniels' (1917) Utah records of Stagnicola traski after all.
No information regarding abundance of this species in Utah has been reported. If the species does indeed occur in this state, it is presumed to be rare; threats to it are not known but would likely be great. Certainly one of the reported Utah localities, the mouth of Ogden Canyon, is in an area that has been and continues to be developed. Loss, alteration, and degradation of aquatic ecosystems in north-central Utah would likely impact any Utah populations of the species. No information regarding population trend of this species in Utah has been reported.
Inventory is needed at the two historical localities of this species' occurrence in Utah as well as elsewhere in north-central Utah. Any inventory work done should emphasize careful identification and determination that any specimens located are truly Stagnicola traski. If it can be found in Utah, an attempt should be made to ascertain its current status (distribution and abundance) in the state.
Habitats Utilized in Utah
Henderson and Daniels (1917) reported this species in Utah from "a small, sluggish stream" and from "sloughs".