Acroloxus coloradensis - (J. Henderson, 1930)
Rocky Mountain Capshell
Taxonomic Status: Accepted
Related ITIS Name(s): Acroloxus coloradensis (J. Henderson, 1930) (TSN 76475)
Unique Identifier: ELEMENT_GLOBAL.2.120617
Element Code: IMGASK8010
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Snails
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Gastropoda Basommatophora Acroloxidae Acroloxus
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Concept Reference
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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.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Acroloxus coloradensis
Taxonomic Comments: Recent DNA sequence data suggests Acroloxus lacustris (and likely other Acroloxus species) is closely related to, and may possibly require placement in, the family Ancylidae along with several species of the family Planorbidae (termed the ancyloplanorbids), prompting tentative proposal of a new family, Anculoplanorbidae (Jorgensen et al., 2004). Albrecht et al. (2004; 2007) concluded, however, that an acroloxid/ancylid relationship is, in fact, an artifact due to insufficient sampling and conclude the Acroloxoidea are monophyletic using four generic taxa of acroloxids. Walther et al. (2006) came to a similar conclusion, suggesting Jorgensen et al. (2004) based their conclusions upon misidentification of a new morphological strain fo Ferrissia fragilis and ancylid, as Acroloxus lacustris; and found ambiguities concerning the partial 16S haplotype of their Acroloxus lacustris, the only dataset supporting evidence of a sister-group relationship between Acroloxus, Ancylus, and Ferrissia.
Conservation Status
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NatureServe Status

Global Status: G3G4
Global Status Last Reviewed: 21Nov2014
Global Status Last Changed: 21Nov2014
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G3 - Vulnerable
Reasons: Very few, extremely small, isolated populations coupled with confined alpine lentic habitat make dispersal of this species unlikely as it is a glacial relict, however several new sites have been discovered in British Columbia (some with healthy populations) where the species is much more widespread, though still patchy.
Nation: United States
National Status: N2 (12Nov2003)
Nation: Canada
National Status: NU (03Aug2017)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Colorado (S1), Montana (S1)
Canada Alberta (S2), British Columbia (S3S4), Manitoba (SU), Ontario (SU)

Other Statuses

Implied Status under the Committee on the Status of Endangered Wildlife in Canada (COSEWIC):NAR,DD
Comments on COSEWIC: Western population is designated Not at Risk. Although the species is known to occur at only a few locations in Canada, it occurs in good numbers in these locations, and there is high probability that this cryptic species occurs in many more locations. Designated Not at Risk in November 2001. Assessment based on a new status report.

Eastern population is designated Data Deficient. Based on old (pre 1970) information, the species is known from few locations. There is no recent information available on distribution, and no information on population size and trends. In addition, there is some uncertainty about the taxonomic identity of the species. Species considered in November 2001 and placed in the Data Deficient category. Assessment based on a new status report.

IUCN Red List Category: VU - Vulnerable

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: 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).

Number of Occurrences: 21 - 80
Number of Occurrences Comments: This species is known from fewer than 30 occurrences or subpopulations (Hossack and Newell 2013); most are in Canada (Anderson 2005).

Known subpopulations include: Six sites in Colorado (Riebesell et al. 2001, Wu 1989); three in Glacier National Park Montana (Ellis et al. 2004, Hossack and Newell 2013); two in Alberta including a recent one in Jasper National Park that is 500 km further south than the original Alberta occurrence (Paul and Clifford 1991, Sovell 2006); three in Quebec, one in Ontario, and at least ten in British Columbia (Lee and Ackerman 2000, 2001; Ellis et al. 2004).

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: Population density varies tremendously within and among locations. Lee and Ackerman (2001) found that the density in Purden Lake in British Columbia, Canada varied from 27 individuals per square meter in one area of the lake to one individual along 80 m of the lake's perimeter. In Gataiga Lake, also in British Columbia, they found only one individual on the entire perimeter of a 34 ha lake. In Lost Lake, Montana, the density was 20 individuals per square meter (Clarke and Hovingh, 1993). Population density in Quebec reached only 0.2 individuals per square meter (Clarke and Hovingh, 1993). Recent surveys by Wu and others (Wu, 1989) in 1973 and 1989 in Peterson Lake, Colorado, revealed only two and one individuals, respectively, compared to up to 72 individuals/m2 in 1970 (Bryce, 1970). The Acroloxus coloradensis density on artificial tiles in an undisclosed national park lake in Colorado steadily increased after monitoring began in 1994 (Riebesell et al., 2001; Anderson, 2005), presumably because individuals were colonizing the tiles. One year after placing tiles on the bottom of the lake, 3.3 individuals per square meter were observed; increasing to 27 per square meter in 1999 and 111 per square meter in 2003. It is unknown at what density the population will level off, or whether it will crash. In Lost Lake, Montana, densities ranged from 0 to 574 per square meter (exceeding all previous published estimates from any site), with a mean of 164 per square meter (Ellis et al., 2004). Density estimates for Trout Lake and Lake No. 1 in Montana were not made but distribution appeared patchy with 25 individuals found in Trout Lake and 7 found in Lake No. 1 and no individuals in Lake No. 5 (previously documented with a population in the 1920s) (Ellis et al., 2004).

Number of Occurrences with Good Viability/Integrity: Few (4-12)
Viability/Integrity Comments: A population in Purden Lake in British Columbia surveyed in 1997 appears to have a large (at least several hundred) and nonlocalized population (Lee and Ackerman, 2000). Population estimates have not been undertaken for other Canadian sites but recent surveys by Wu and others (Wu, 1989) in 1973 and 1989 in Peterson Lake, Colorado, revealed only two and one individuals, respectively, compared to up to 72 individuals/m2 in 1970 (Bryce, 1970). The species still remains fairly abundant in Lost Lake, Montana, and no genetic variation was demonstrated among Rocky Mountain populations selected for analysis (Ellis et al., 2004).

Overall Threat Impact: Medium
Overall Threat Impact Comments: Habitat degradation and loss is the biggest threat. The remaining lentic habitats are in an area of rapid urbanization and population growth (Boulder County). Specific habitat of Peterson Lake is not on protected land. Winter snowmaking by the nearby Eldora Ski Resort results in water level drawdowns of Peterson Lake. Salting of the roads has become more frequent to accommodate winter skiers and snowboarders (personal observation). Wu (1989) indicated the remaining habitats are highly polluted. Anderson (2005) assessed the following potential threats: changes in water levels (even though Acroloxus coloradensis can probably survive some change in water level because they are mobile, they still depend on the presence of water so low water levels caused by weather-related drought conditions are difficult to alleviate; however, diversion or impounding of water can contribute to low water levels in some areas), roads (three lakes in Colorado (including one with Acroloxus coloradensis) had very high calcium levels and conductivities; these sites were adjacent to roadways, and Riebesell et al. (2001) suggests that the high levels could be due to salts, dust, and/or emissions from the roads), motorized recreation (possibly increase erosion or direct mortality due to vehicles entering water), non-motorized recreation (although no studies have been conducted, several tiles used in a study by Riebesell et al. (2001) that were located near a hiking trail disappeared, suggesting some recreational user disturbance), timber harvest (impacts documented for other species but not for this species yet), mining (no current activities but remnants of historical mining activity near Lost Lake indicate that, at least in some situations, Acroloxus coloradensis can co-exist with mining, but impacts not assessed), over-utilization (likely none except possibly for scientific or collection purposes), fisheries management (none), pesticide treatment (not studied for this species), exotic species (currently none present but invasion by Dreissena polymorpha or Potamopyrgus antipodarum would negatively impact the species), fire (not assessed for this species), and grazing (no information available). Although present in fish guts in Montana, the species does not appear to be very sensitive to fish predation but densities were found to decrease where humans accessed the lakes to walk and swim (Ellis et al., 2004).

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: See Wu (1989) and Riebeell et al. (2001). Surveys by Wu and others (Wu, 1989) in 1973 and 1989 in Peterson Lake, Colorado, revealed only two and one individuals, respectively, compared to up to 72 individuals/m2 in 1970 (Bryce, 1970). Several new sites, however, have been discovered in British Columbia recently and these appear stable and very widespread (Lee and Ackerman, 2001). The species still remains fairly abundant in Lost Lake, Montana (Ellis et al., 2004).

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: Fossilized specimens were reported in the Berends and Dixon Pleistocene assemblages distributed across southwestern Kansas, portions of Oklahoma and in north central Nebraska (Taylor, 1954; 1960)

Intrinsic Vulnerability: Moderately vulnerable
Intrinsic Vulnerability Comments: Very few, extremely small populations coupled with confined lentic habitat make dispersal of this species unlikely in the southern portions of its range (U.S.) (Anderson, 2005); but populations in Canada (particularly British Columbia) are more widespread over a large area (though still patchy) and have adapted to lotic habitats in Alberta (Lee and Ackerman, 2001).

Environmental Specificity: Narrow to moderate.
Environmental Specificity Comments: This species was once thought to be an extreme environmental specialist in small alpine lakes only, but studies (Riebessell et al., 2001) have shown that 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). Also, the species has adapted to the slow moving portions of a few Canadian streams as well (Lee and Ackerman, 2001; Anderson, 2005).

Other NatureServe Conservation Status Information

Inventory Needs: Survey other Rocky Mountain states in alpine lakes; especially those in disjunct areas between existing populations. Assess trend information for existing populations.

Protection Needs: Protect Colorado populations (Peterson Lake may be too late, but new populations found in five other lakes) and other bottlenecked, disjunct populations with few individuals.

Distribution
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Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) 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).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States CO, MT
Canada AB, BC, MB, ON

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CO Boulder (08013), Jackson (08057)
MT Flathead (30029), Glacier (30035)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
09 St. Marys (09040001)+
10 North Platte Headwaters (10180001)+, Upper North Platte (10180002)+, St. Vrain (10190005)+
17 North Fork Flathead (17010206)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): CREEK, Pool
Lacustrine Habitat(s): Shallow water
Special Habitat Factors: Benthic
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 ” cm versus 24 ” 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).
Economic Attributes Not yet assessed
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Management Summary
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Biological Research Needs: Life history and population dynamics of remaining populations outside U.S. plus new populations in Colorado need study. Very little information is available on any aspect of the biology and life history of Acroloxus coloradensis. The response of Acroloxus coloradensis to changes in habitat is not well understood. Information on how it responds to changes in temperature, water level, or water clarity and the relationship of these factors to management activities would allow better planning of buffers and mitigation measures.
Population/Occurrence Delineation
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Group Name: Freshwater Snails

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information.
Mapping Guidance: Unlike most freshwater mussels [possibly excepting Uniomerus tetralasmus (Say, 1831) (see Isley, 1914)], some freshwater pulmonates are able to survive in intermittent streams and ponds by settling into sediment on the bottom and aestivating in otherwise dry or frozen conditions. Some species (e.g. Stagnicola spp.) may form a sheet of mucus just within the aperture called an epiphragm that effectively seals the snail from harsh external conditions (Jokinen, 1978; Brown, 1991). For ephemeral or intermittent water species, it may be particularly difficult to define the limits of an occurrence. Movement out of the water for the purposes of aestivation is on the order of cm (Jokinen, 1978), not m or km, so this behavior should not affect separation distance between occurrences. Species that may be found in intermittent waters include: Aplexa elongata, Fossaria bulimoides, F. dalli, F. modicella, F. obrussa, F. parva, Gyraulus circumstriatus, G. crista, G. parvus, Laevapex fuscus, Physa vernalis, Physella gyrina, Planorbella campestris, Planorbula armigera, Stagnicola caperata, S. elodes, S. exilis.
Separation Barriers: Separation barriers are largely based on permanent hydrological discontinuity between water bodies, with distances of 30 meters or greater between maximum high water marks constituting a separation barrier. Additional barriers are chemical and/or physical and include any connecting water body (regardless of size) with one or more of the following on a permanent basis: no dissolved calcium content, acidity greater than pH 5, lack of dissolved oxygen, extremely high salinity such as that found in saline lakes and brine waters, or temperature greater than 45

An additional physical barrier, particularly for flowing water, is presence of upland habitat between water connections. High waterfalls and anthropogenic barriers to water flow such as dams are barriers as they limit movement in an upstream direction.

Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 2 km
Alternate Separation Procedure: Freshwater cave species (mostly prosobranchs) may occur near entrances to very deep in cave systems with specimens occurring on the undersides of small stones in riffle areas (Hershler et al., 1990). For cave species, separation distance cannot often be determined accurately due to varying degrees of accessibility to occupied cave habitat. In these instances, each cave where an observation or collection was recorded (see Minimum EO Criteria, above) constitutes an element occurrence regardless of separation distance. Multiple caves within a single hydrological cave system are each considered separately. Caves with multiple entrances and passages known to be connected, but with connecting passages too small or unsafe for human entry shall be treated as a single element occurrence when the non-negotiable portion of the cave is thought to be less than approximately 300 m linear length. Species known to occur in caves include: Amnicola cora, Antrobia spp., Antrobis spp., Antroselates spp., Dasyscias spp., Fontigens aldrichi, F. antroecetes, F. bottimeri, F. morrisoni, F. nickliniana, F. orolibas, F. prosperpina, F. tartarea, F. turritella, Holsingeria spp., Phreatodrobia spp., Stygopyrgus spp.
Separation Justification: Freshwater snails have adapted to most North American habitats including permanent standing, intermittent, and flowing waters. As a whole, pulmonates (previously Subclass Pulmonata) are better dispersers than prosobranchs (previously Subclass Prosobranchia). Pulmonates adapt better to changing temperature and oxygen concentration, resist desiccation better (use pulmonary respiration, store excreted nitrogen as urea, aestivate), and have faster crawling rates (including righting response and actual movement rate) than prosobranchs (Brown et al., 1998). Some species are more tolerant to adverse habitat conditions such as high pollution levels (e.g. Physella spp.), high altitude [e.g. Acroloxus coloradensis (Henderson, 1930)], underground cave pools and springs (e.g. Fontigens spp., Phreatodrobia spp.) and hot springs (e.g. Pyrgulopsis spp.).

Precise geographic distribution of many American freshwater snails is not known but presumably reflects past geological, geographic, and climatic change (Smith, 1989). Movements between isolated or inaccessible portions of water bodies is possible but dependent on outside, passive processes (e.g. rafting, periodic flooding, transport by vertebrates, introduction by humans). Long-distance dispersal is generally not considered when assigning separation distances as otherwise impracticably large separation distances would result.

Several factors contribute to limiting freshwater snail distribution but none apply across diverse habitats or taxa. Approximately 95% of all freshwater gastropods are restricted to waters with calcium concentrations greater than 3 mg/liter (Brown, 1991; for exceptions see Jokinen, 1983). Calcium uptake for shell construction requires energy expenditure (active transport) when calcium concentration is low, but is passive at higher concentrations (Greenaway, 1971). Typically, no known biotic or abiotic factors consistently limit the abundance or distribution of freshwater gastropods among sites (DeVries et al., 2003). At specific localities, limiting factors may include hardness, acidity, dissolved oxygen, salinity, high temperature, and food availability as associated with depth (Smith, 1989). Most species and the largest populations occur in hard, alkaline waters with normal range 20-180 ppm (Shoup, 1943; Harman, 1974). Snails are uncommon in habitats with surface acidity greater than pH 5 (see also Jokinen, 1983). Dissolved oxygen limits diversity so severely polluted waters (oxygen consumed by algae blooms) are often devoid of freshwater snails excepting pollution tolerant species. Because pulmonates can utilize atmospheric oxygen, they can exist under anaerobic conditions for longer time periods (Harman and Berg, 1971; Harman, 1974; McMahon, 1983). High salinity is limiting to freshwater gastropods and inland saline lakes generally lack an associated snail fauna. Most species (excepting hot springs species) are intolerant of temperatures greater than 45șC (McDonald, 1969; van der Schalie and Berry, 1973), a condition rarely occurring naturally. Lower temperatures are less limiting as snails have been found foraging in ice-covered waters (Harman and Berg, 1971; Harman, 1974). Most species live in the shallows, (depths less than 3 m) where food abundance is greatest. As a result, drastic water fluctuations (draw-downs) may cause declines in snail populations (Hunt and Jones, 1972).

Any contiguous, occupied stretch of suitable flowing water habitat 2 km long or greater is considered an element occurrence. Two km was chosen based upon the limited active movement capabilities of most benthic invertebrates and observed home range of freshwater snails (J. Cordeiro, personal observation) as well as the relatively short life span of most species (five years for most stream species and two years for most pond species).

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Prosobranchs: Neritidae: Neritina; Viviparidae: Campeloma, Cipangopaludina, Lioplax, Tulotoma, Viviparus; Ampullariidae: Marisa, Pomacea; Pleuroceridae: Elimia, Goniobasis, Gyrotoma, Io, Juga, Leptoxis, Lithasia, Pleurocera; Thiaridae: Melanoides, Tarebia; Bithyniidae: Bithynia; Hydrobiidae: Amnicola, Antrobia, Antrorbis, Antroselates, Aphaostracon, Balconorbis, Birgella, Cincinnatia, Clappia, Cochliopa, Cochliopina, Colligyrus, Dasyscias, Eremopyrgus, Floridiscrobs, Fluminicola, Fontelicella, Fontigens, Gillia, Heleobops, Holsingeria, Hoyia, Hydrobia, Lepyrium, Littoridina, Littoridinops, Lyogyrus, Notogillia, Onobops, Paludina, Phreatoceras, Phreatodrobia, Potamopyrgus, Pristinicola, Probythinella, Pyrgophorus, Pyrgulopsis, Rhapinema, Somatogyrus, Spilochlamys, Spurwinkia, Stiobia, Stygopyrgus, Taylorconcha, Texadina, Texapyrgu, Tryonia; Assimineidae: Assiminea; Pomatiopsidae: Pomatiopsis, Heterostropha; Valvatidae: Valvata
MORE IN BCD EO SPECS NOTES TAB

Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 22Nov2014
NatureServe Conservation Status Factors Author: Cordeiro, J., Sears, N., Ormes, M.
Element Ecology & Life History Edition Date: 12Jun2008
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Albrecht, C., K. Kuhn, and B. Streit. 2007. A molecular phylogeny of Planorboidea (Gastropoda, Pulmonata): insights from enhanced taxon sampling. Zoologica Scripta, 36: 27-39.

  • Albrecht, C., T. Wilke, T. Kuhn, and B. Streit. 2004. A molecular phylogenetic perspective on the evolution of freshwater pulmonate snails (Gasommatophora). Molluscan Mega-diversity: Sea, Land and Freshwater, Volume 1. World Congress of Malacology: Perth, Australia.

  • Anderson, T. (2005, January 20). Rocky Mountain Capshell Snail (Acroloxus coloradensis): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/rockymountaincapshellsnail.pdf [date of access].

  • Anderson, T. 2005. Rocky Mountain capshell snail (Acroloxus coloradensis) a technical conservation assessment. Report prepared for the USDA Forest Service, Rocky Mountain Region, Species Conservation Project, January 20, 2005. 26 pp.

  • Basch, P. 1963. A review of the recent freshwater limpet snails of North America. Bulletin of the Museum of Comparative Zoology, Harvard University, 129: 399-461.

  • Bryce, G.W., Jr. 1970. Rediscovery of the Limpet, Acroloxus coloradensis, in Colorado. The Nautilus 83(2): 105-108.

  • Bryce, G.W., Jr. 1970. Rediscovery of the limpet, Acroloxus coloradensis (Basommatophora: Acroloxidae) in Colorado. Nautilus 83:105-108.

  • Burch, J.B. and J.L. Tottenham. 1980. North American freshwater snails, IV. Species lists, ranges and illustrations. Walkerana 1(3): 81-215.

  • Clarke, A.H. 1970. On Acroloxus coloradensis (Henderson) (Gastropoda, Basommatophora) in eastern Canada.. National Museums of Natural Sciences, Publications in Zoology, No. 2 National Musuems of Canada, Ottawa. 13 pp.

  • Clarke, A.H. 1973. The Freshwater Molluscs of the Canadian Interior Basin. Malacologia. Volume 13, Number 1-2. 509 pp.

  • Clarke, A.H. 1981. The Freshwater Molluscs of Canada. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Ontario. 446 pp.

  • Clarke, A.H. 1981. The freshwater molluscs of Canada. National Museum of Natural Sciences, Ottawa. 446 pp.

  • Clarke, A.H. and P. Hovingh. 1993. Final Report: Status survey of fifteen species and subspecies of aquatic and terrestrial mollusks from Utah, Colorado, and Montana. Ecosearch, Inc., Portland, Texas. Report submitted to U.S. Fish and Wildlife Service. Contract no. 14-16-0006-91-046 (revised).

  • Dillon, R.T. Jr. 2000. The ecology of freshwater molluscs. Cambridge University Press, Cambridge, UK. 509 pp.

  • Ellis, B.K., L. Marnell, M.A. Anderson, J.A. Stanford, C. Albrecht, and T. Wilke. 2004. Status and ecology of a glacial relict mollusk, the Rocky Mountain capshell limpet (Acroloxus coloradensis), in relation to the limnology of Lost Lake, Glacier National Park, Montana (USA). Open File Report 186-05. Prepared for National Park Service, Glacier National Park, West Glacier, Montana by Flathead Lake Biological Station, The University of Montana, Polson, Montana. 63 pp.

  • Frest, T. J. and E. J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report to the Interior Columbia Basin Ecosystem Management Project. Walla Walla, WA, USA

  • General Status, Environment Canada. 2015. Manitoba Mollusk species list and subnational ranks proposed by an expert.

  • Harrold, M.N. and R.P. Guralnick. 2010. A field guide to the freshwater mollusks of Colorado. 2nd edition. Colorado Division of Wildlife, Denver. 73 pp

  • Hossack, B.R., and R.L. Newell. 2013. New distribution record for the rare limpet Acroloxus coloradensis (Henderson, 1930) (Gastropoda: Acroloxidae) from Montana. The Nautilus 127(1):40-41.

  • Jorgensen, A., T.K. Kristensen, and J.R. Stothard. 2004. An investigation of the "Ancyloplanorbidae" (Gastropoda, Pulmonata, Hygrophila): preliminary evidence from DNA sequence data. Molecular Phylogenetics and Evolution 32: 778-787.

  • Lee, J. S. and J.D. Ackerman. 1999. British Columbia freshwater mollusc collections from north of 54°Latitude made during 1997. Preliminary Report prepared for the Conservation Data Centre, Ministry of Environment, Victoria, BC, Canada. 151 pp.

  • Lee, J. S. and J.D. Ackerman. 2001. Draft COSEWIC status report on the Rocky Mountain Capshell Acroloxus coloradensis (J. Henderson, 1930). University of Northern British Columbia, Prince George. 21pp.

  • Lee, J.S and J.D. Ackerman. 2001. COSEWIC Status Report on The Rocky Mountain Capshell, Acroloxus coloradensis (J. Henderson, 1930). Committee on the Status of Endangered Wildlife in Canada. 11 pp + maps + appendices.

  • Lee, J.S. 2000. Freshwater molluscs of British Columbia: assessments for all known or potential taxa. Unpubl. rep. submitted to the BC Conservation Data Centre, Minist. Envrion., Lands and Parks, Victoria, BC. 107pp.

  • Lee, J.S. 2000b. Freshwater molluscs. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 6 pp.


  • 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.

  • Lee, J.S. and J.D. Ackerman. 2000. Freshwater molluscs at risk in British Columbia: three examples of "risk". Pages 67-74 in L. Darling (ed.) Proceedings of a Conference on the Biology and Management of Species and Habitats at risk, Kamloops, British Columbia, 15-19 February 1999. British Colubmia Ministry of Environment, Lands, and Parks, Victoria, British Columbia; and University of the Cariboo, Kamloops, British Columbia. 490 pp.

  • Lee, J.S. and J.D. Ackerman. 2001. COSEWIC Status Report on The Rocky Mountain Capshell Acroloxus coloradensis (J. Henderson, 1930). Unpublished report submitted to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

  • Lepitzki, D. 2014. General Status rank assessment of freshwater molluscs of British Columbia. Prepared for Canadian Wildlife Service, Environment Canada. Gatineau, PQ.

  • NatureServe Explorer:an online encyclopedia of life [web application]. 2001. Version 1.6. Arlington, Virginia, USA:NatureServe. Available: http://www.natureserve.org/explorer. (Accessed Jan. 8, 2002.)

  • Paul, A.J. and H.F. Clifford. 1991. Acroloxus coloradensis (Henderson), a rare North American freshwater limpet. The Nautilus 105(4): 173-174.

  • Pioneer Environmental Services, Inc. 1993. Results of survey for the Rocky Mountain Capshell Snail in Colorado alpine lakes.

  • Riebesell, J.F., T.L. Thrasher, A. Bazzi, and W.P. Kovalak. 2001. Habitat characteristics of Rocky Mountain (Colorado) populations of Acroloxus coloradensis. American Malacological Bulletin 16(1/2): 33-40.

  • Scudder, G.G.E. 1994. An annotated systematic list of the potentially rare and endangered freshwater and terrestrial invertebrates in British Columbia. Occ. Pap. 2, Entomol. Soc. B.C. 92pp.

  • Scudder, G.G.E. 1996. Terrestrial and freshwater invertebrates of British Columbia: priorities for inventory and descriptive research. Research Branch British Columbia Ministry of Forests Research Program, and Wildlife Branch, British Columbia Ministry of Environment, Lands and Parks. Victoria, British Columbia, Working Paper 09/1996.206 pp.

  • Sovell, J. 2006. Rocky Mountain capshell snail (Acroloxus coloradensis) a technical conservation assessment; supplement. Update to T. Anderson 2005 Report prepared for the USDA Forest Service, Rocky Mountain Region, Species Conservation Project, January 20, 2005. 8 pp.

  • Stagliano, D.M., G.M. Stephens, and W.R. Bosworth. 2007. Aquatic invertebrate species of concern on USFS Northern Region lands. Report prepared for USDA Forest Service, Northern Region, Missoula, Montana. Montana Natural Heritage Program, Helena, Montana and Idaho Conservation Data Center, Boise, Idaho. Agreement number 05-CS-11015600-036. 95 pp. + app.

  • Taylor, D.W. 1954. A new Pleistocene fauna and new species of fossil snails from the High Plains. Occasional Papers of the Museum of Zoology, University of Michigan, 557: 16 pp.

  • Taylor, D.W. 1960a. Late Cenozoic molluscan faunas from the High Plains. U.S. Geological Survey Professional Paper, 337: 94 pp.

  • 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.

  • Walther, A.C., T. Lee, J.B. Burch, and D.O. Foighil. 2006. Acroloxus lacustris is not an ancylid: a case of misidentification involving the cryptic invader Ferrissia fragilis (Mollusca: Pulmonata: Hygrophila). Molecular Phylogenetics and Evolution, 39: 271-275.

  • Wu, S.-K. 1989. Colorado freshwater mollusks. Natural History Inventory of Colorado 11: 1-117.

  • Wu, Shi-Kuei and Biodiversity Legal Foundation. 1992. Petition for a Rule to emergency list the Rocky Mountain Limpet snail, Acroloxus coloradensis, as endangered in the United States.

  • Wu, Shi-Kuei. 1989. Colorado freshwater mollusks. Natural History Inventory of Colorado 11:9-10.

  • Zammit, A.E., and D.A. Sutherland. 2001. COSSARO Candidate V,T,E, Species Evaluation Form for Rocky Mountain Capshell (Acroloxus coloradensis). Unpublished report prepared for Committee On the Status of Species At Risk in Ontario. 4 + appendices.

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