Garlic Glass-snail - Oxychilus alliarius
Helix alliaria, Zonitoides alliaria
A small shell, to 7 mm diameter and 3 mm in height but often smaller, flattened heliciform, smooth with some fine incremental striae, about 5-6 whorls, the last expanding to the aperture. Shell coloration is translucent amber brown on the upper surface, lighter on the undersurface. Aperture is large, oblique crescent-shaped, without teeth (denticles); periphery rounded; umbilicus about 1/6 the shell diameter. The animal is dark gray to blackish and emits a strong garlic odor when handled (Hendricks 2012, Burke 2013). Internal anatomy is described by Giusti and Manganelli (1997).
Oxychilus differ from other species by a combination of a generally smooth and translucent shell lacking a flared lip, no banding, an enlarged body whorl at the aperture less than half the diameter, a narrow umbillicus, a low to flattened spire. O. alliarius differs from O. draparnaudi by being smaller (8 mm diameter compared to 10-16 mm), having a very smooth and glossy shell, and possessing a strong garlic odor when disturbed.
Western Europe; introduced elsewhere, including North America. In Montana, only one report from Lee Metcalf National Wildlife Refuge, Ravalli County, west of the Continental Divide; elevation 991 m (3250 ft). First reported for Montana in 2009. Range and abundance poorly documented in Montana; current status needs investigation. Probably occurs in many additional urban settings and valley bottoms (Hendricks 2012).
Observations in Montana Natural Heritage Program Database
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Frequents moist sites in parks, gardens, and other modified habitats. Found at Lee Metcalf National Wildlife Refuge at the edge of a water-filled slough under woody debris, leaf litter, and grassy vegetation, with nearby black cottonwood canopy. 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.
- Giusti, F., and G. Manganelli. 1997. How to distinguish Oxychilus cellarius (Mueller, 1774) easily from Oxychilus draparnaudi (Beck, 1837) (Gastropoda, Pulmonata, Zonitidae). Basteria 61:43-56.
- 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.
- Additional ReferencesLegend: View Online Publication
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- 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.
- Pilsbry, H.A. 1946. Land Mollusca of North America (north of Mexico), Volume II Part 1. Academy of Natural Sciences of Philadelphia Monograph Number 3 (2):1-520.
- Additional Sources of Information Related to "Snails / Slugs"