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The biogeographic history of aquatic organisms in relation to the Wasatch Mountains divide (which separates the eastern Great Basin and upper Colorado River basin in Utah) has been little studied aside from a large body of work on fishes. Pyrgulopsis kolobensis is a small springsnail that is distributed (in the eastern portion of its range) along the western flanks of the Wasatch Mountains, with a single population occurring just across the Wasatch divide in Strawberry Valley. Here we analyze the genetic structure of this species across the Wasatch divide (using the mtCOI gene) to discriminate between alternative hypotheses that explain this distributional pattern. The 6 P. kolobensis populations that we sampled were resolved as a single, weakly supported and shallowly structured clade in a Bayesian analysis. Specimens from Strawberry Valley shared a unique haplotype and differed from the other populations by 0.3%–0.8% sequence divergence, suggesting a geologically recent split that well postdat...

I determined the distribution of limpets (Gastropoda: Ancylidae: Ferrissia) in the Colorado River and Rio Grande basins by handpicking specimens from the undersides of rocks and vegetation at 16 sites from a total of 495 surveyed sites in Colorado, Utah, New Mexico, and Arizona. Shell morphology, including morphometries, was compared to species holotype descriptions and museum lots. Ferrissia rivularis occurred in the upper Colorado, Gunnison, and San Juan rivers, and in the upper Rio Grande basin. Ferrissia walkeri, hereafter called the Walker morph, occurred only in the Gila River basin of Arizona and New Mexico. I reviewed the problems of classification of the Walker morph as being either F. walkeri, described from Arkansas and noted in Michigan and Baja California Sur, or Ferrissia fragilis, described from California and noted from the eastern United States. The Walker morph is identified by its vertical trending protoconch, which lies well within the right posterior quadrant, with the apex ...

Leech species of the mid-Snake River of Idaho and Oregon are described, and the distribution of the extant leech Mooreobdella microstoma Moore in the Snake River paleodrainage is delineated. Samples were collected from aquatic surveys in the Snake River using suction dredging by the Idaho Power Company and U.S. Bureau of Reclamation between 1995 and 2006. Supplementing these surveys, opportunities were provided for leech identification in water-quality analyses in Arizona and Wyoming and in other surveys in California, Oregon, Washington, and Idaho. Eight species of leeches were found in the Snake River surveys. Erpobdella parva Moore was the most widely distributed species, occurring both above and below Shoshone Falls. Mooreobdella microstoma was widely distributed below Shoshone Falls. Other leech species were rare, although Helobdella stagnalis Linnaeus was very common above and less common below Shoshone Falls, a natural barrier to the anadromous fish. Mooreobdella microstoma is an extant sp...