Robust Walker – State Wildlife Action Plan

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Pomatiopsis binneyi has a moderately high and conical shell, with 4-5 deeply and evenly convex whorls; a complete aperture; shell moderately thick with whitish opaque layer immediately inside and lining aperture. The shell has been described as consisting of four to five very convex whorls; apex somewhat obtuse; aperture ovate or nearly suborbicular, both lips rounded; umbilicus very small; color light-horn. It is much smaller than any other Pomatiopsis species.

Overview

Species Common Name Robust Walker
Species Scientific Name Pomatiopsis binneyi

Ecoregions

Columbia Plateau

The Columbia Plateau ecoregion was shaped by cataclysmic floods and large deposits of wind-borne silt and sand earlier in its geological history. It is dominated by a rolling landscape of arid lowlands dissected by several important rivers, and extends from the eastern slopes of the Cascades Mountains, south and east from the Columbia River to the Blue Mountains.

Special needs

Robust walkers are semi-aquatic snails typically associated with riparian areas in trickling water such as perennial seeps and rivulets. It is also found on shallow mud banks and marsh seepages that lead to shallow streams. In Oregon, this species has been observed or collected from springs with sand-cobble bottoms, creeks with mud-cobble substrate, and spring seeps with mud substrate.

Limiting factors

Habitat loss is a primary threat to P. binneyi. Any activity or event that can alter springs or seeps, including affects to water quantity (e.g., from groundwater withdrawal) and water quality (e.g., dissolved oxygen, temperature, sedimentation, pollution), as well as activities that can alter the surrounding terrestrial habitat where this species occurs can be considered a threat to this species. In particular, sedimentation resulting from road or timber harvest activities could impact P. binneyi populations.

Data gaps

Determine species-specific habitat requirements. Assess the tolerance range of this species to environmental change. Document species range. Collect current population status and trend data.

Conservation actions

Protect known sites of occurrence. Monitor known populations and habitats. Survey suitable habitat for new populations.

Key reference or plan

Hietala-Henschell, K., S. Foltz Jordan, T. Stone, and R. Huff. 2019. Interagency Special Status/Sensitive Species Program (ISSSSP) Species Fact Sheet: Pomatiopsis binneyi. USDA Forest Service Region 6 and USDI Bureau of Land Management Oregon State Office. 18 pp.