Microphysula ingersollii (Bland, 1875)
- Helix ingersollii Bland 1875: 151, unnumbered figure.
- Microphysa ingersolli [sic] convexior Ancey 1887b: 64.
- Thysanophora ingersolli [sic] meridionalis Pilsbry & Ferriss 1910: 116, fig. 24d–f.
Identification. Shell subdiscoid. Spire only slightly raised. Whorls ca 5, rather closely coiled and slowly enlarging. Suture moderately indented. Periphery of last whorl rounded. Aperture narrowly lunate, edentulous. Lip thin, simple. Umbilicus small, ca ¼ of shell width. Protoconch smooth. Teleoconch smoothish, with weak incremental lines and fine, close, spiral lines. Shell with a silky lustre, translucent, milky whitish. Width to 4.8 mm (wider than high).
Animal pale, whitish; body, through shell at spire pale pinkish.
Habitat. Montane forests, avalanche tracks, and subalpine meadows. Especially common in limestone areas. Under rocks and dead wood, and in leaf litter.
Canadian range. BC: Pine Pass, Rocky Mountains, south to the USA border (Forsyth 2004). Alberta: Rocky Mountain Foothills, including in Waterton Lakes National Park (unpubl. data).
Etymology. Named after Ernest Ingersoll (1852–1946), a naturalist, writer, and explorer, who travelled west with the US Geological Survey’s Hayden surveys of 1874 and 1877.
Remarks. See M. cookei.
The species epithet is frequently misspelled ingersolli, but according to the ICZN (1999), the original spelling Ingersollii (Bland 1875) should be emended to ingersollii (Article 18.104.22.168), but the -ii termination must not be changed to a single-i (Article 33.4).
The date of publication is frequently incorrect in the literature; the part of the Annals of the Lyceum of Natural History of New York in which the species was described appeared in 1875, not 1874 (Bequaert & Miller 1973).
Two subspecific taxa have been described. Henderson & Daniels (1917) noted that Ancey (1887) was misled by Bland’s (1875) figure when he described Microphysa ingersolli [sic] convexior, and Pilsbry (1940) agreed that topotypic material from Utah was indistinguishable from M. ingersollii. Thysanophora ingersolli [sic] meridionalis was described by Pilsbry & Ferriss (1910) for shells having a wider aperture than typical ingersollii, slightly looser coiling of the whorls, and a nearly flat spire; Pilsbry (1940) continued to treat this taxon as a valid subspecies but in connection with the modern genus Microphysula. Bequaert & Miller (1973) included meridionalis as a synonym of M. ingersollii but did not give their reasoning. Thus, neither of these subspecific taxa are in current use.
- Ancey C-F (1887) Description of North American shells. The Conchologists’ Exchange 2: 63–64.
- Bequaert JC, Miller WB (1973) The mollusks of the arid southwest with an Arizona checklist. University of Arizona Press, Tucson, xiv + 271 pp.
- Bland T (1875) Note on the sub-generic character of Helix Jamaicensis Chemn., and on certain terrestrial molluscs from Haiti; with description of a new species of Helix from Colorado. Annals of the Lyceum of Natural History of New York 11: 146–154.
- Forsyth RG (2004) Land Snails of British Columbia. Royal British Columbia Museum, Victoria, iv + 188 +  pp.
- Henderson J, Daniels LE (1917) Hunting Mollusca in Utah and Idaho in 1916. Proceedings of the Academy of Natural Sciences of Philadelphia 69: 48–81.
- ICZN (1999) International code of zoological nomenclature. Fourth edition. International Trust for Zoological Nomenclature, London.
- Pilsbry HA, Ferriss JH (1910) Mollusca of the southwestern states: IV. The Chiricahua Mountains, Arizona. Proceedings of the Academy of Natural Sciences of Philadelphia 62: 44–147.