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Vespericola sierranus is a pulmonate (air-breathing) land snail. This species is a small, thin-shelled, brown snail with a moderately elevated, rounded spire that is slightly angled at the periphery. With 5.25 to 5.75 whorls, the shell measures 8.4 to 9 mm wide by 5.2 to 5.8 mm high. V. sierranus rarely has a parietal tooth, is distinctly umbilicate, and lacks teeth on the lip.
The Siskiyou hesperian is primarily a riparian associate found in perennially moist habitat at 533 to 1493 m (1750 to 4900 ft.) of elevation. It is found near spring seeps and pools and alongside other freshwater habitats, including streams or in wet areas with running water. Moist valley, ravine, gorge, or talus sites are preferred, near the lower portions of slopes in areas that are not subject to regular flooding. This species also may be found in marsh areas under woody debris. V. sierranus seeks refuge in deep leaf litter and under other forest floor substrates, including duff and rocks. Additionally, it is found in association with open and shallow outcrops of basalt along small, cold spring runs with moss and grass covered rocks.
Limiting factors
Habitat loss, including spring alteration and decreased water flow, represents a major threat to Siskiyou hesperian. Sedimentation and nutrient inputs from dredging, mining, road construction, and other land use practices may smother substrates or reduce egg survival.
Data gaps
Assess distribution. Determine species-specific habitat requirements and life history traits. Continue taxonomic research and determine population genetics. Collect current population status and trend data. Assess the tolerance range of this species to environmental change.
Conservation actions
Maintain appropriate water flow and quality. Prevent or mitigate for water diversions, dredging, or other activities that could increase sediment or nutrient levels. Monitor known populations and survey suitable habitat for new populations.
Key reference or plan
Blackburn, M., R. Hatfield, S. Foltz Jordan, and T. Stone. 2021. Interagency Special Status/Sensitive Species Program (ISSSSP) Species Fact Sheet: Vespericola sierranus. USDA Forest Service Region 6 and USDI Bureau of Land Management Oregon State Office. 26pp.
