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Montana Field Guide

Montana Field Guides

Ninepipes Ambersnail - Oxyloma missoula
Other Names:  Oxyloma retusum, Oxyloma retusa

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Native Species

Global Rank: G2G4
State Rank: SNR

Agency Status

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General Description
Shell is oblong-ovate (succineiform), very thin and fragile, about 14.5 mm in length and 7.5 mm in width, with 3 whorls, the spire about 1/3 the length of the shell. Shell coloration is pale amber. Aperture is oblique and ovate, with a thin lip. The head and tentacles are grayish-brown, mantle with dark gray spots and streaks. The original description was based on animals collected at Ninepipes National Wildlife Refuge, Lake County (Hendricks 2012). Internal anatomy is described by Harris and Hubricht (1982).

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 in Montana and Utah. In Montana, reported on both sides of the Continental Divide from five counties: Beaverhead, Lake, Lewis and Clarks, Lincoln, Teton. Elevation range is about 853 to 1494 m (2800 to 4900 ft). Range and abundance are poorly understood in Montana; current status need investigation (Hendricks 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 13

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Relative Density



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

Wetlands, lakeshore areas, stream sides. Habitat poorly defined in Montana (Hendricks 2012).

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Citation for data on this website:
Ninepipes Ambersnail — Oxyloma missoula.  Montana Field Guide.  .  Retrieved on , from