Terrestrial Gastropods of the Columbia Basin, British Columbia
DISCIDAE Thiele, 1931
Genus Anguispira Morse, 1864
Anguispira kochi (Pfeiffer,1845): Banded Tigersnail
Synonym. Patula solitaria occidentalis Von Martens, 1892.
Description: Shell large (width to 25.3 mm), subheliciform; surface matt; opaque, dark brown, and usually with a lighter periphery band bordered by two obscure darker bands; spire moderately elevated; whorls about 6 and very convex; periphery rounded; suture deep; protoconch smoothish; early teleoconch with regular, low axial riblets becoming coarser and less regular on subsequent whorls, with fine axial striae; aperture deeply rounded; outer lip only very slightly thickened and then only in very mature individuals; no denticles within the aperture; base very convex; umbilicus medium-sized, about 20% of the width.
Juveniles less than about half grown have a somewhat angular periphery. The animal is pale brownish or brownish-cream with a tinge of ochre; tentacles are darker, greyish-brown.
Similar species: Juveniles can be recognised from juvenile Allogona ptychophora by the larger umbilicus and less angular periphery. A. kochi differs from most specimens of Oreohelix by having a darker pigmented shell, but separation of eroded or long dead shells of A. kochi from some Oreohelix is often difficult.
Habitat: In British Columbia, it is known from moist, wooded, well-vegetated areas, often near the shores of lakes and streams.
Range: There are two disjunct populations: southeast British Columbia, south through Washington, Idaho and Montana to Oregon (Pilsbry 1948) east of the Cascade Mountains (Smith 1943); and Lake Erie south and west to Kentucky, Missouri and Arkansas (Pilsbry 1948).
Distribution: This species is restricted the southern Columbia-Kootenay River valleys in British Columbia.
Notes: The eastern and western populations were judged by Pilsbry (1948) to be subspecifically distinct. He called the western population Anguispira kochi occidentalis (Von Martens, 1882).
Name: Genus name meaning "snake-spire".
Records: Near Syringa Creek, Lower Arrow
Lake (circa 49°21.1'N, 117°54.6'W) (Forsyth Coll.
97-113-4241); Boswell, Kootenay Lake (49°28.46'N, 116°46.0'W)
(Forsyth Coll. 97-100-863); Grohman Narrows Park, near Nelson (49°29.8'
N, 117°20.8'W) (Forsyth Coll. 97-112-3001); Nelson (49°30'N,
117°06'W) (RBCM 991-00095-007); Near Lockhart Creek, Kootenay
Lake (49°30.6'N, 116°47.1'W) (Forsyth Coll. 97-099-1038);
E shore of Kootenay Lake, S of Gray Bay, Hwy. 3A (49°33.59'N,
116°47.72'W) (Forsyth Coll. 97-098-4239); McDonalds Landing,
West Arm, Kootenay Lake, near Six Mile, NE of Nelson (49°34.75'N,
117°12.99'W) (Forsyth Coll. 97-094-1037); Kokanee Landing (49°36'N,
117°06'W) (RBCM 996-00010-002, 996-00010-003); Kokanee Creek
Park, West Arm, Kootenay Lake (49°36.2'N, 117° 07.7'W) (Forsyth
Coll. 97-095-1089); Six Mile Lakes near Nelson (49°40'N, 117°17'W)
(Pilsbry 1948); Schroeder Creek, near Hwy. 31, N of Kaslo (50°01.95'N,
116°54.55'W) (RBCM 998-00263-002); Meadow Creek, near N end
of Kootenay Lake (50°13.97'N, 116°57.37'W) (RBCM 998-00262-001).
View the map.
Genus Discus Fitzinger, 1833
Discus whitneyiDescription: Shell small (width, 6.7 mm), depressed-heliciform; subtranslucent brown or occasionally pale coloured; spire low; whorls 4.5, convex or a little angular (especially in juveniles); suture deep; protoconch without riblets; teleoconch with nearly equally spaced axial riblets, extending onto the base, and fine axial striae; aperture rounded and without denticles; outer lip unthickened; umbilicus rather large, about 33-40% of the width of the shell.
Animals are pale grey on the sides and tail and dark grey or blackish on the back, head and tentacles (Pilsbry 1948).
Similar species: Discus shimekii is similar, but the axial ribs are absent or weak on the base. Paralaoma caputspinulae (Punctum comspectum is a synonym) has the appearance of small D. whitneyi, but the umbilicus is narrower and the protoconch sculptured in the first species.
Habitat: This is an ubiquitous species living in wooded areas under leaf litter, under logs, and under vegetation around the shores of lakes as well as in dry, exposed areas, at low and high elevations. In Montana this gastropod has been found at 3,048 m [10,000 ft] (Vanatta 1914).
Distribution: D. whitneyi occurs throughout most of the province, but is not common on the coast.
Notes: This widely spread and well-known species was previously called Discus cronkhitei, but Discus whitneyi predates that name (Roth 1987a). Dall (1905), Bequaert & Miller (1973) and Roth & Lindberg (1981) have alluded to the strong resemblance of this snail to D. ruderatus (Férussac, 1821) of the northern Europe and Asia.
Populations of this species are variable, with some shells having the periphery more angled than others; these have been given the name anthonyi.
Name: Species name after Professor Whitney, patron to the California Academy of Natural Sciences, San Francisco.
Valley Wildlife Management Area (49°07.19'N, 116°37.82'W)
(RBCM 998-00282-006); Creston Valley Wildlife Management Area (49°07.34'N,
116°37.24'W) (RBCM 998-00264-005); Wigwam River (49°15'N,
115°06'W) (Berry 1922);
Moyie Lake (49°22.3'N, 115°51.0'W) (Forsyth Coll. 97-102-1044);
Coal Creek on E side of Cokato Road, Fernie (49°29.72'N, 115°3.75'W)
(Forsyth Coll. 97-108-1046); Crowsnest Pass Rest Area, Crowsnest
Pass (49°39.06'N, 114°41.76'W) (RBCM 998-00297-002); S of
ferry, Kootenay Bay, E side of Kootenay Lake (49°40.4'N, 116°52.3'W)
(Forsyth Coll. 97-097-1097); along road to Cody Caves, hillside
near Ainsworth (49°45.7'N, 116°54.7'W) (Forsyth Coll. 97-096-4238);
Cummings Creek, N of Sparwood (49°46.32'N, 114°54.95'W)
(RBCM 998-00293-003); Schroeder Creek, near Hwy 31, north of Kaslo
(50°01.95'N, 116°54.55'W) (RBCM 998-00263-003); N end of
Trout Lake, E of Upper Arrow Lake; (50°38.75'N, 117°32.32'W)
(RBCM 998-00285-005); Roadside, Hwy. 1, Eagle Pass, E of Clanwilliam,
W of Revelstoke (50°58.2'N, 118°21.0'W) (Forsyth Coll. 98-097-3282);
Along Hwy 1, W of Revelstoke, B.C., at junction with Hwy 23 (51°00.2'N,
118°13.4'W) (Forsyth Coll. 98-096-3319); Sale Creek Road, Revelstoke
(51°09.1'N, 118°11.0'W) (RBCM 998-00260-003); Hwy 1, 4 km
E of Canyon Hot Spring (circa 51°09.5'N, 117°49'W)
(Staaliches Museum für Naturkunde Görlitz); W of snow
sheds, Hwy 1, Glacier National Park (circa 51°15.5'N,
117°28'W) (Staaliches Museum für Naturkunde Görlitz);
Hunter Creek Forest Recreation Site, along Kicking Horse R., ESE
of Golden (51°15.95'W, 116°44.69'N) (Forsyth Coll. 98-092-3298);
Field (51°24'N, 116°29'W) (Vanatta
1906); Sherbrooke Trail head, N of Wapta Lake, Yoho National Park
(circa 51°26.4'N, 116°21.5'W) (Forsyth Coll. 98-090-3388);
Doyle Rest Area, Hwy 1, 20 km N of Golden (51°26.55'N, 117°05.31'W)
(RBCM 998-00275-004); unnamed creek, W of Brewster Creek (51°38.32'N,
118°32.32'W) (RBCM 998-00257-002); Lake Revelstoke, Hwy 37 to
Mica Dam (51°39.56'N, 118°33.73'W) (RBCM 998-00258-002);
Lake Revelstoke, Hwy 23 to Mica Dam (51°39.56'N, 118°33.73'W)
(RBCM 998-00261-002). View the map.
Description: Shell small (width to 6.5 mm), more or less depressed-heliciform, subtranslucent, yellowish brown; spire moderately elevated or flattened; whorls 4.5, convex; periphery rounded; protoconch smooth; teleoconch with regular, strong axial riblets with fine axial striae between; riblets rarely extending onto the base and becoming lower and irregular on the last whorl; aperture typically rounded, or more ovate in the flattened form of the species; aperture without denticles; outer lip unthickened; umbilicus rather large, about 30% of the width of the shell.
Similar Species: Compare with Discus whitneyi.
Habitat: Discus shimekii is a characteristically montane species living under rocks and dead wood. In Arizona it has been found at altitudes of 2,195-3,658 m [7,200-12,000 ft] (Bequaert & Miller 1973). Discus shimekii is sympatric with the more common and widespread D. whitneyi.
Range: Lindeman Lake, British Columbia (Pilsbry 1948, Forsyth 1999), east and south to Jasper (Platt 1980) and Kananaskis, Alberta (Berry 1922), south to New Mexico and Arizona (Pilsbry 1948, Bequaert & Miller 1973).
Distribution: Discus shimekii is not as widespread as D. whitneyi. In British Columbia, it is known from records at Lindeman Lake (Randolph 1899; Pilsbry 1948; Forsyth 1999) and near Atlin in the Northwest and southeast along the Rocky Mountain range.
Notes: Somewhat smoother, more depressed shells with a wider umbilicus have been named Discus shimekii cockerelli (Pilsbry 1898). However, Beetle (1957) noted that a series of specimens from Wyoming showed a gradual transition from low to high spired individuals, and variation in the size of the umbilicus and sculpture was also evident. Pilsbry (1948), and more recently Bequaert & Miller (1973), treated cockerelli as a synonym of D. shimekii.
Name: Genus name meaning "a disc". Species name honouring Bohumil Shimek who collected the specimens under Pilsbry's study (Pilsbry 1890). Shimek was a long-time friend of H.A. Pilsbry, with whom he began the study of shells as a boy (Pilsbry 1948).
Records: Cummings Creek, N of Sparwood (49°46.32'N, 114°54.95'W) (RBCM 998-00293-006). View the map.
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