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Montana Field Guides

Oblique Ambersnail - Oxyloma nuttallianum
Other Names:  Succinea nuttalliana, Succinea rusticana

Native Species

Global Rank: G2G4
State Rank: SNR

Agency Status

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General Description
Shell is oblong-ovate (succineiform), to about 17 mm in length and 9 mm in width, thin, about 3 whorls with a short spire. Shell coloration is transparent, pale yellow. Aperture is oblique, ovate, elongate, about 3/4 the shell length. Head and foot covered with minute black dots patterned somewhat in spots or stripes (Hendricks 2012, Burke 2013). Internal anatomy is described by Pilsbry (1948).

Diagnostic Characteristics
The Succineidae is a most difficult family, with no sure way of distinguishing genera, let alone species, from shell characteristics. In general, Catinella have shorter shells with a rounder aperture and relatively higher spire. Succinea are larger-shelled with more ovate apertures and swelling around the genital opening behind the right tenticle. Oxyloma are similar in size to Succinea but are narrower (larger ratio of height to width), with longer, narrower, ovate apertures (Burke 2013). Specific determination requires the aid of an expert.

Species Range
Montana Range


Range Comments
Native to western North America, from British Columbia to northern Baja California, Mexico, east to Montana. In Montana, reported west of the Continental Divide from three counties: Flathead, Missoula, Ravalli. Elevation range is 884 to 1219 m (2900 to 4000 ft). All records of O. retusum (= retusa) west of the Continental Divide (from Flathead, Lake, and Lincoln counties) may be this species or O. missoula; O. retusum is considered an eastern North American species. Range and abundance in Montana poorly understood; current status needs investigation (Hendricks 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 5

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Riparian areas near rivers, streams, lake shores, bogs and springs. Habitat in Montana poorly documented (Hendricks 2012).

  • Literature Cited AboveLegend:   View Online Publication
    • Burke, T. E. 2013. Land snails and slugs of the Pacific Northwest. Corvallis, OR: Oregon State University Press. 344 p.
    • Hendricks, P. 2012. A Guide to the Land Snails and Slugs of Montana. A report to the U.S. Forest Service - Region 1. Montana Natural Heritage Program, Helena, MT. vii + 187 pp. plus appendices.
    • Pilsbry, H.A. 1948. Land Mollusca of North America (north of Mexico), Volume II Part 2. The Academy of Natural Sciences of Philadelphia Monograph Number 2(2): 521-1113.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Elrod, M.J. 1901a. Collecting shells in Montana. Nautilus 15:86-89, 103-110, 110-112, 129-130.
    • Elrod, M.J. 1902. Daphnia pond, a study in environment. University of Montana Bulletin #16, Biological Series 5: 230-233.
    • Forsyth, R.G. 2004. Land snails of British Columbia. Royal British Columbia Museum: Victoria, British Columbia, Canada. 188 pp.
    • Frest, T.J. and E.J. Johannes. 2001. An annotated checklist of Idaho land and freshwater mollusks. Journal of the Idaho Academy of Science 36(2):1-51.
    • Henderson, J. 1924. Mollusca of Colorado, Utah, Montana, Idaho, and Wyoming. University of Colorado Studies 13(2):65-223.
    • Henderson, J. 1936. Mollusca of Colorado, Utah, Montana, Idaho, and Wyoming, supplement. University of Colorado Studies 23(2): 81-145.
    • Vanatta, E.G. 1914. Montana shells. Proceedings of the Academy of Natural Sciences of Philadelphia 66:367-371.
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Citation for data on this website:
Oblique Ambersnail — Oxyloma nuttallianum.  Montana Field Guide.  .  Retrieved on , from