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Montana Field Guide

Montana Field Guides

Marshall Ambersnail - Oxyloma decampi
Other Names:  Oxyloma gouldi

Native Species

Global Rank: G5
State Rank: SNR

Agency Status

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General Description
Shell oblong-ovate (succineform), to 15 mm in length and 7.5 mm in width. very thin, surface with minute striae, about 3 whorls with a short spire. Shell coloration is translucent, pale yellow, sometimes with a rose tint. Aperture is ovate, long and relatively thin, about 3/4 the shell length. Sutures are moderately impressed, but not as deep as Catinella. Head and neck covered with minute black dots (Hendricks 2012, Burke 2013). Reports of O. gouldi in Montana are included with this species.

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.

Range Comments
Native to eastern North America, west to eastern Montana and Colorado. In Montana, reported east of the Continental Divide from Wibaux County and a questionable report from Madison County. Elevation at the Wibaux County location is 823 m (2700 ft). Range and abundance in Montana are poorly understood; current status needs investigation (Hendricks 2012).

Observations in Montana Natural Heritage Program Database
Number of Observations: 2

(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)

Priarie riparian areas near rivers, streams,and springs. Canopy species include cottonwoods. Found under woody debris and leaf litter in moist places. Habitat in Montana is poorly described (Hendricks 2012).

Food Habits
No information for Montana.

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