Allogona profunda

Allogona (Allogona) profunda (Say, 1821)
Broad-Banded Forestsnail

  • Helix profunda Say 1821: 160.
  • Helix (Helicella) richardii A. Férussac in A. Férussac & Deshayes 1823 in 1819–1851: pl. 70 [3 lower figures].
  • Polygyra profunda var. alba B. Walker 1899: 12, non Polygyra multilineata var. alba Witter, 1878.
  • Polygyra profunda var. unicolor B. Walker 1899: 12.
  • Polygyra profunda strontiana G. H. Clapp 1916: 537, pl. 32, figs 13–15.
  • Polygyra profunda var. pleistocenica F. C. Baker 1920: 66.
  • Polygyra profunda efasciata Walker 1924: 33, nomen novum pro P. profunda var. alba B. Walker 1899.
Allogona profunda at Fish Point, Pelee Island, Ontario. Upper right individual has an epiphragm sealing the aperture. [RF]

Identification. Shell flattened-heliciform, with a low, conical spire. Whorls c. 5–6, convex. Periphery rounded to slightly shouldered above in adults. Aperture subovate; 1 low, rounded basal denticle on inner edge of basal lip. Lip broadly expanded, little recurved. Umbilicus c. 1/5 of shell width. Protoconch smooth. Teleoconch with rather regular, strongly oblique, sinuous colabral riblets (strongest on the apical surface), microscopic wrinkles and spiral striae; no malleated sculpture. Shell semi-opaque; cream- to reddish-buff, usually with rusty-brown band or bands of varying number and width; lip whitish. Width to 27.0 mm (wider than high).

Animal light brown, flecked with white on dorsum; head and ocular tentacles darker (Baker 1902).

Habitat. Stony and sandy woodlands, such as Common Hackberry woods and sandy savannas. Under dead wood, in leaf litter, and climbing vegetation.

Canadian range. Southern Ontario: Point Pelee, Pelee Island, and historically several other Lake Erie islands.

Etymology. Latin, profundus, “deep”.

Remarks. Pilsbry (1940) recognized A. profunda strontiana, a form described by Clapp (1916) from the Erie islands. This taxon was regarded as a synonym by Hubricht (1985), although the reasons why were never stated by him. However, Pilsbry hinted that these island forms intergrade in appearance with typical mainland shells. Within populations, colour is variable, with bands either lacking or variously developed. Pilsbry (1940) included colour varieties as synonyms.

Allogona profunda, Point Pelee, Ontario. 2016 [RF].
  • Baker FC (1902) The Mollusca of the Chicago area: the Gastropoda. The Chicago Academy of Sciences, Natural History Survey, Bulletin 3: 133–410 + [138] pp. + pls 128–136.
  • Baker FC (1920) Animal life in loess deposits near Alton, Illinois, with descriptions of two new varieties of land shells from the same deposits. The Nautilus 34: 61–66.
  • Clapp GH (1916) Notes on the land-shells of the islands at the western end of Lake Erie and descriptions of new varieties. Annals of Carnegie Museum 21: 532–540, pls 32–36.
  • Férussac AEJPF d’Audebard de, Deshayes G-P (1819–1851) Histoire naturelle générale et particulière des mollusques terrestres et fluviatiles, tant des espèces que l’on trouve aujourd’hui vivantes que des des dépouilles fossiles de celles qui n’existent plus; classés d’après les caractères essentiels que présentent ces animaux et leurs coquilles. J.-B. Baillière, Paris, France. • Tome 1: 8 + 184 pp. • Tome 2 (1): [1–3], 1–402; (2): 1–260, 1–22, [1–2], i–xvi • Atlas 1: 70 pls • Atlas 2: 166 + 5 pls.
  • Hubricht L (1985) The distributions of the native land mollusks of the eastern United States. Fieldiana, Zoology (New Series) 24: i–viii, 1–191.
  • Pilsbry HA (1940) Land Mollusca of North America (north of Mexico). Vol. I, Part 2. The Academy of Natural Sciences of Philadelphia, Monographs3: i–viii + 575–994 + i–ix.
  • Say T (1821) Descriptions of univalve shells of the United States. Journal of the Academy of Natural Sciences of Philadelphia 2: 149–179.
  • Walker B (1899) The terrestrial Mollusca of Michigan. B. Walker, Detroit, MI, USA, 27 pp.
  • Walker B (1924) The varietal names of Polygyra profunda (Say). The Nautilus 38: 33–34.