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Montana Field Guide

Montana Field Guides

Thin-lip Vallonia - Vallonia perspectiva


Global Rank: G4G5
State Rank: SNR

Agency Status
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General Description
A very small and thin shell, to about 2 mm diameter and 0.8 mm in height, flattened heliciform, with a series of evenly spaced ribs, to about 3 1/3 whorls, gradually increasing in size and flattened above and below the periphery, the last rapidly descending, suture deep. Shell coloration is translucent pale amber to colorless. Aperture is inclined, oblique-ovoid, without a thickened lip; umbilicus wide, about 1/2 the shell diameter. Animal is white (Hendricks 2012).

Diagnostic Characteristics
Combination of small size (< 3.5 mm diameter), flattened heliciform shape, flared lip, and color (translucent white to pale brown) separate Vallonia from other shells. An unthickened lip distinguish V. cyclophorella and V. perspectiva from V. pulchella and V. gracilicosta. V. cyclophorela has regularly spaced blade-like axial ribs, and an umbilicus about 1/3 the shell diameter while V. perspectiva has evenly-spaced ribs and an umbilicus about 1/2 the shell diameter. V. cyclophorella is similar in structure to Vallonia perspectiva but larger (up to 3.4 mm diameter compared to 2.0 mm, respectively).

Species Range
Montana Range

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Range Comments
North America throughout the eastern and southwestern United States to Mexico. In Montana, reported east of the Continental Divide only from Wibaux County, elevation 823 m (2700 ft)(Squyer 1894, Hendricks 2012). Range and abundance in Montana poorly understood; current status needs investigation. Identification questionable. The Wibaux County record (Squyer 1894) was attributed by Henderson (1924) to Vallonia parvula, whereas Pilsbry (1948) made no mention of the Wibaux County record in his accounts of V. perspectiva or V. parvula.

Summary of Observations Submitted for Montana
Number of Observations: 1

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Habitat
Driers sites on hillsides, rocky outcrops, near springs, and streamside riparian habitat, including cottonwood and willow. Found under rocks and woody debris, in leaf litter, and drift material (Hendricks 2012). Habitat in Montana poorly documented.

References
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Citation for data on this website:
Thin-lip Vallonia — Vallonia perspectiva.  Montana Field Guide.  .  Retrieved on , from