BC Conservation Data Centre: Species Summary
Acroloxus coloradensis
Rocky Mountain Capshell
| Scientific Name: | Acroloxus coloradensis (J. Henderson, 1930) | ||||||||||
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| English Name: | Rocky Mountain Capshell | ||||||||||
| Classification / Taxonomy | |||||||||||
| Scientific Name - Concept Reference: | Turgeon, D. D., J. F. Quinn, Jr., A. E. Bogan, E. V. Coan, F. G. Hochberg, W. G. Lyons, P. M. Mikkelsen, R. J. Neves, C. F. E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F. G. Thompson, M. Vecchione, and J. D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland. 526 pp. | ||||||||||
| Classification Level: | Species | ||||||||||
| Species Group: | Invertebrate Animal | ||||||||||
| Species Code: | MO-ACRCOL | ||||||||||
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| Conservation Status / Legal Designation | |||||||||||
| Global Status: | G3G4 (Nov 2014) | ||||||||||
| Provincial Status: | S3S4 (Nov 2024) | ||||||||||
| BC List: | Blue | ||||||||||
| Provincial FRPA list: | |||||||||||
| Provincial Wildlife Act: | |||||||||||
| COSEWIC Status: | Not at Risk (Nov 2001) | ||||||||||
| SARA Schedule: | |||||||||||
| General Status Canada: | |||||||||||
| Ecology & Life History | |||||||||||
| General Description: | |||||||||||
| Migration Characteristics: (Global / Provincial) | |||||||||||
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Nonmigrant: Local Migrant: Distant Migrant: Within Borders Migrant: |
N / N / N / na / |
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| Habitats: (Type / Subtype / Dependence) |
Lakes / Lake / Obligate
Lakes / Pond/Open Water / Obligate |
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| Global Habitat Comments: | Habitat is high altitude lakes and ponds. In Colorado, typically found at elevations between 2675 and 3025 m that have conductivity >20 umhos/cm, calcium > 50 mg/L, and glacial deposits along at least part of shorelines. Rocky substrates, small drainage basins (< 250 ha), and macrophytic vegetation are often (but not always) associated (Riebesell et al., 2001). Most known populations occur in lakes, but a recent discovery occurred in a very slowly-moving portion of Beaver River in Alberta, Canada (Paul and Clifford, 1991). In a study of comparative habitat, Riebessell et al. (2001) found lakes with A. coloradensis were significantly lower in elevation (2864 m versus 3074 m) than lakes without the species [but higher in elevation than lakes with other snail species] had higher calcium content (104 mg per L versus 49 mg per L), and higher in conductivity (39 µ cm versus 24 µ per cm) than lakes without A. coloradensis. This indicates the species may be limited to lakes in an elevation band low enough to have enough calcium and other ions, but high enough to have rocky substrate that is not too muddy (as is common in highly productive lakes and lakes with large amounts of runoff, such as is seen commonly at lower elevations). Densities in Lost Lake, Montana, were highest where flat rocks were piled in layers in relatively shallow water (<1 m) and where the area was not utilized by people for wading and swimming (Ellis et al., 2004). | ||||||||||
| Provincial Habitat Comments: |
In rocky, exposed portions of oligotrophic and mesotrophic lakes; in shallow water on the underside of rocks and vegetation on wave-swept shores (Clarke 1981; Lee and Ackerman 2001). |
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| Food Habits: | |||||||||||
| Global Food Habits Comments: | |||||||||||
| Global Phenology: | |||||||||||
| Provincial Phenology: (1st half of month/ 2nd half of month) |
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| Colonial Breeder: | N | ||||||||||
| Length(cm)/width(cm)/Weight(g): | / / | ||||||||||
| Elevation (m) (min / max): |
Global:
Provincial: |
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| Distribution | |||||||||||
| Endemic: | N | ||||||||||
| Global Range Comment: | This species is the only representative of the family Acroloxidae in North America and is broadly distributed across southern Canada (Paul and Clifford, 1991, L. Ramsey, pers. comm. 2004, Lee and Ackerman, 2000) and south into the Rocky Mountains of Montana and Colorado (Burch and Tottenham 1980, Wu, 1989, Hossack and Newell 2013). The isolated populations indicates a relictual glacial distribution. Canadian populations are divided into disjunct eastern populations (Ontario and Quebec) and western populations (British Columbia and Alberta) (Anderson, 2005). In Colorado, it has been recorded from alpine lakes in Boulder County, Rocky Mountain National Park, and both Routt and Roosevelt National Forests (Riebesell et al. 2001, Harrold and Guralnick 2010). In Montana, it is known from Glacier National Park (Anderson 2005, Stagliano et al. 2007, Hossack and Newell 2013). Fossil occurrences are known for Nebraska, Kansas, and Oklahoma (Clarke and Hovingh 1993). |
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| Authors / Contributors | |||||||||||
| Global Information Author: | Cordeiro, J. | ||||||||||
| Last Updated: | Jun 12, 2008 | ||||||||||
| Provincial Information Author: | French, L. | ||||||||||
| Last Updated: | Nov 04, 2004 | ||||||||||
| References and Related Literature | |||||||||||
Lee, J.S. 2000b. Freshwater molluscs. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 6 pp. |
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Lee, J.S. and J.D. Ackerman. 2000. Freshwater Molluscs at Risk in British Columbia: Three Examples of "Risk". Pp. 67-73 in L.M. Darling, ed. 2000. Proc. Conf. on the Biology and Manage. Species and Habitats at Risk, Kamloops, B.C., 15 - 19 Feb., 1999. Vol. 1; B.C. Minist. Environ., Lands and Parks, Victoria, BC, and Univ. College of the Cariboo, Kamloops, BC. 490pp. |
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Please visit the website Conservation Status Ranks for definitions of the data fields used in this summary report.
Suggested Citation:
B.C. Conservation Data Centre. 2008. Species Summary: Acroloxus coloradensis. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 4, 2026).