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Terrestrial
Gastropods of the Columbia Basin, British Columbia
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| Family PUNCTIDAE Morse,
1864
Genus Punctum Morse, 1864 Punctum cf. californicum Pilsbry, 1898: Ribbed Spot Description: Shell very small (width to about 1.8 mm), light chestnut brown and with a shining lustre; spire moderately elevated; whorls convex and about 3.75 in number; periphery rounded; suture deep; protoconch smooth; teleoconch with fine, closely spaced axial riblets (bearing very narrow lamellar edges) and with finer axial and spiral striae between; aperture rounded and without denticles; outer lip thin and unexpanded; umbilicus about 20% of the width of the shell. Similar Species: Punctum californicum is very similar to P. randolphii (Dall, 1895) and is said to differ by being slightly larger and having a lower spire and less developed axial riblets (Pilsbry 1948), but see Notes below. Another punctid not yet known from the Columbia Basin but likely to be discovered there is Paralaoma caputspinulae (Reeve, 1852); Punctum conspectum (Bland, 1865) is a synonym (see Roth 1985, 1987b). It is larger (width to 2.4 mm) than P. californicum, and the protoconch is sculptured with granules initially and then widely spaced spiral striae. The teleoconch has larger, more widely spaced axial riblets. Habitat: In Arizona, Punctum californicum has been collected at elevations up to 2,743 m [9,000 ft] (Pilsbry 1948). Berry (1919) reported specimens collected from under sticks, bark, small logs and loose rock at elevations of 1,113-1,768 m [3,650-5,800 ft] in and adjacent to Glacier National Park, Montana. The British Columbia record is that of a dead shell collected from the foot of wet rock. Range: Previously known from northern Montana and South Dakota, Colorado, Arizona and California (Pilsbry 1948), Punctum californicum is now also recorded from British Columbia for the first time. Distribution: Punctum californicum is known in British Columbia only by a single, broken specimen (see Records). Notes: Pilsbry (1948) noted that this species and Punctum randolphii may possibly be the same species. The coastal Punctum, considered to be P. randolphii, is a much more variable shell than credited by Pilsbry and in other literature. In the single, damaged specimen coming from the Kootenay region, and here provisionally referred to as P. californicum, the spire is as elevated as typical P. randolphii. Name: Genus name meaning "a dot", in reference to the small size of this snail. Species named for California. Records: W of snow sheds, Hwy 1, Glacier National Park (circa 51°15.5'N, 117°28'W) (Staatliches Museum für Naturkunke Görlitz p5959). View the map. |
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