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Terrestrial
Gastropods of the Columbia Basin, British Columbia
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OREOHELICIDAE Pilsbry, 1939 There are two species known in British Columbia. Species and populations of Oreohelix have been differentiated by size, proportions, colour and sculpture; however, a great range of variation exists, perhaps due to subtle differences in ecology between individual populations (Solem 1975). Pilsbry (1939) grouped allied species and "subspecies" of Oreohelix. He noted that the shell of O. strigosa has, in general, a taller, more conical form than the shell of O. subrudis and defined these groups using male reproductive morphology. The penis sac is divided into an internally muscular, ribbed part near the proximal end and a distal papillose section. In the O. strigosa group of species the muscular, ribbed portion of the penis is decidedly less than half of the entire length. In the O. subrudis group of species, the internally ribbed portion is half, or more than half, of the total length of the penis. Recently, however, Rees (1988) found that the morphology of the penis sac was highly variable and suggested that Pilsbry's methods of classifying individuals is unclear using both reproductive morphology and relative height of the shell. O. subrudis and O. strigosa may be geographically segretated from each other. Identification of Oreohelix into species is
provisional and based wholly upon shell characters. Oreohelix strigosa
(Gould, 1846): Rocky Mountain Snail
Description: Shell medium-sized to large (width, 16-26 mm), variable in form, but typically depressed-heliciform, opaque, of rough texture; pale, greyish-white to dark brownish; often with darker bands of brown; bands variable, typically with 1 prominent band above and another just below the periphery; additional narrower, fainter bands below the latter band on base; sometimes only the bands on the base show as faint traces; a pale brownish/yellowish periostracum is mostly eroded away; spire low-conical to more raised and extremely variable within populations; apex blunt and spire therefore somewhat domed; whorls convex and about 6 in number, with the periphery weakly to sharply angular (juveniles have angulate periphery, a character that is retained in adults of some individuals or in some populations); suture deep; protoconch with fine, close, raised spiral striae crossed by more or less evenly spaced axial riblets; teleoconch with coarse, irregular axial riblets and striae; there may be faint traces of spiral sculpture in some; aperture ovate to rounded and without denticles; outer lip scarcely thickened or only slightly thickened within by a low ridgelike callus; lip slightly flared in most mature shells; umbilicus moderately open and dependent upon the amount that a shell is depressed, about 20-25% of the shell width. Similar Species. See the comments above, for the genus. Habitat: Vegetated rock slides. Rees (1988) indicated that Oreohelix subrudis and O. strigosa "are separated geographically: O. subrudis predominates in the streamside habitat, whereas O. strigosa occurs among the rock-slide rubble." Both Pilsbry (1939) and Branson (1980) remarked that this species has a markedly discontinuous range in Washington, and that it is restricted mostly the dry side of the mountains where it lives mostly under talus. Biology: Members of the genus Oreohelix are viviparous. Range: Cypress Hills, southeast Alberta; southeast British Columbia and adjacent parts of Alberta, south through Idaho, Montana, eastern Washington, eastern Oregon, Wyoming, South Dakota, Utah, Colorado, Arizona and New Mexico (Dall 1905, Pilsbry 1939, Russell 1951). This is the range of Oreohelix strigosa as a whole, including all named subspecies, forms and mutations. Distribution: In British Columbia, Oreohelix strigosa is restricted to the Columbia Basin region and occurs as far north as Donald Station, the type locality for Oreohelix strigosa canadica Berry, 1922, and the northernmost locality for the genus. Name: Genus name meaning "mountain snail"; species name meaning "lean". Records: S end of Creston Valley Wildlife
Management Area (49°05.64'N, 116°37.31'W) (RBCM 998-00281-002);
Creston Valley Wildlife Management Area (49°07.34'N, 116°37.24'W)
(RBCM 998-00264-002); Kuskanook Rest Area, Hwy 3A (49°17.11'N,
116°39.17'W) (Forsyth Coll. 97-101-1008); Lodgepole Creek Road
to Flathead (49°20.01'N, 114°56.67'W) (RBCM 998-00296-003);
Near Sand Creek, Betania Road, W of Galloway (49°22.23'N, 115°14.59'W)
(Forsyth Coll. 97-105-908); Elk River valley, along Hwy 3, S of
Ski Hill Road, S of Fernie (circa 49°27.5'N, 115°04.2'W)
(Forsyth Coll. 97-109-1017); Bull River bridge, Wardner-Fort Steele
Rd., SE of Fort Steele (49°28.39'N, 115°26.95'W) (Forsyth
Coll. 97-110-906); Boswell, Kootenay Lake, B.C. (49°28.46'N,
116°46.0'W) (Forsyth Coll. 97-100-870); Kokanee Landing (49°36'N,
117°06'W) (RBCM 996-00010-001, 996-00010-004); Kokanee Creek
Park, West Arm, Kootenay Lake (circa 49°36.2'N, 117°07.7'W)
(Forsyth Coll. 97-095-1088); Schroeder Creek near Hwy 31, N of Kaslo
(50°01.95'N, 116°54.55'W) (RBCM 998-00263-001); Donald Station
(51°29.5'N, 117°10.6'W) (Berry
1922, Pilsbry 1939). View
the map. Oreohelix subrudis
(Reeve, 1854): Subalpine Mountainsnail
Oreohelix subrudis 
Description: Shell medium-sized to large
(width, 16-23 mm), variable in form, but typically heliciform or almost
bee-hive-shaped, opaque, rough textured; pale, greyish-white to dark
brownish; often with darker bands of brown variable as in Oreohelix
strigosa; periostracum pale brownish/yellowish, mostly eroded
off; spire moderately raised in typical shells to distinctly raised
but extremely variable and often complexingly similar to O. strigosa;
apex blunt; spire rather domed; whorls about 6, convex and with the
periphery weakly angular (juveniles have a distinctly angulate periphery;
suture deep; protoconch with fine, close, raised spiral striae crossed
by more or less evenly spaced axial riblets; teleoconch with coarse,
irregular axial riblets and striae; there may be traces of spiral
sculpture in some; aperture ovate to rounded and without denticles;
outer lip scarcely thickened or only slightly thickened within by
a low, ridgelike callus; lip slightly flared in most mature shells;
umbilicus about 20-25% of the shell width. Similar Species: See the comments above, for the genus. Habitat: Along streams and in swamps. Range: Cypress Hills, Saskatchewan-Alberta (Russell 1951); Southeast British Columbia and southwest Alberta through Idaho, Montana, Wyoming, Utah, Colorado, Arizona and New Mexico Pilsbry (1939). Distribution: In British Columbia, this species is limited to the Columbia Basin. Name: Species name meaning "somewhat rough". Records:Wigwam River (circa 49°15'N, 115°06'W) (Berry 1922); Moyie Lake (49°20'N, 115°50'W) (Berry 1922); Coal Creek valley near Fernie (circa 49°30'N, 115°04'W) (Pilsbry 1939); near Hosmer, Hwy 3 between Fernie and Sparwood (49°34.94'N, 114°58.05'W) (RBCM 998-00299-001); Crowsnest Pass (49°38'N, 115°04'W) (Pilsbry, 1939); Crowsnest Pass Rest Area ( 49°39.06'N, 114°41.76'W) (RBCM 998-00297-001). View the map. |
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