Category Archives: Mollusca

Zonitoides arboreus

Zonitoides arboreus, Cypress Hills, Alberta. [RF]

Zonitoides (Zonitoides) arboreus (Say, 1817)
Pale Gloss

  • Helix arboreus Say 1817a: unpaginated; pl. 4, fig. 4.
  • Helix ottonis L. Pfeiffer 1840: 251.
  • Helix breweri Newcomb 1864: 118.
  • Hyalina arborea var. viridula Cockerell 1888: 257.
  • Hyalinia (Polita) roseni Lindholm 1911: 98.
  • Alienator lyndhurtoides Mclaughlan 1954: 40.
  • Zonitoides (Zonitellus) azoricus Riedel 1964: 46, figs 38–40, 41, 42.
  • ? Zonitoides ostauri Pilsbry 1926: 100, fig. 24.

Identification. Shell strongly depressed, subdiscoidal. Spire low, convex. Suture moderately impressed. Whorls c. 4½–5, convex. Protoconch smooth. Teleoconch with irregular, weak incremental wrinkles, weaker on base, and exceedingly faint spiral striae (difficult to see even under high magnification). Aperture deeply lunate, wider than high, edentulous. Lip thin, simple. Umbilicus c. 1/5 of shell width. Shell translucent, yellow- to red-brown, glossy or glassy. Shell width to 6 mm (wider than high).

This species lacks the dull orange spot on the mantle, which is evident in Z. nitidus, and the animal is paler. The shell has exceedingly fine spiral striae, which at c. 50× are still difficult to make out. Aegopinella nitidula is larger, the shell has relatively coarser spiral striae, and the umbilicus is larger and with a milky- white opacity surrounding it. Species of Oxychilus are smoother, glossier, and spiral striae are absent.

Habitat. A wide variety of natural habitats, including forests and open habitats, where it occurs under rocks, within rotten wood, leaf litter and vegetation.

Global range. Native to North America, south in Mexico to Veracruz and Puebla (Correa-Sandoval et al. 2007), Central America, and the West Indies. Introduced to South America, Europe, some North Atlantic islands, North and southern Africa, the Middle East, Japan, Australia (Long 1972, Bishop 1978, Smith 1992, Seddon 2008), and Hawaii (Pilsbry 1946, Barker 1999). Said to be native to Kamchatka (Dall 1905, Likharev & Rammel’meier 1962) and Japan (Likharev & Rammel’meier 1962).

Canadian range. Ubiquitous, in nearly every province and territory; likely in Nunavut (southern islands in Hudson Bay likely).

Etymology. Latin: of the trees.

Remarks. This species was described as Helix arboreus by Say (1817) in his article “Conchology” that appeared in volume 2 of the American Edition of the British Encyclopedia. Although usually dated 1816, this part was published in 1817 (Johnson 1975).

Syntypes of Helix whitneyi, which long considered a junior synonym of Z. arboreus (e.g. Pilsbry 1946), were examined by Roth (1988) who found them to belong to Discus (see Discus whitneyi).

  • Barker GM (1999) Naturalised terrestrial Stylommatophora (Mollusca: Gastropoda). Fauna of New Zealand/Ko te Aitanga Pepeke o Aotearoa 38: 1–253.
  • Bishop MJ (1978) Zonitoides arboreus (Say) (Pulmonata: Zonitidae) introduced into Australia and the identity of Alienator Iredale. Journal of the Malacological Society of Australia 4 (1-2): 7–8.
  • Cockerell TDA (1888) Mollusca in Colorado. Hardwicke’s Science Gossip 24: 257.
  • Correa-Sandoval A, Strenth NE, Salazar Rodríguez MC (2007) Zoogeografía de los gastrópodos terrestres del sur de Nuevo León, México. Acta Zoológica Mexicana (n.s.) 23: 143–162.
  • Dall WH (1905) Land and fresh water mollusks. Harriman Alaska Expedition. Vol. 13. Doubleday, Page and Co., New York, 1–171, pls 1, 2.
  • Johnson RI (1975) First paper on the conchology of the United States by an American author, Thomas Say, 1817. Journal of the Society for the Bibliography of Natural History 7 (3): 265–267.
  • Likharev IM, Rammel’meier ES (1962) Terrestrial mollusks of the fauna of the U.S.S.R. Keys to the Fauna of the USSR. Israel Program for Scientific Translations, Jerusalem, [4] + 574 pp.
  • Lindholm WA (1911) Bemerkungen über einige Hyalinien Russlands nebst Beschreibung einer neuen Art. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft 43: 94–99.
  • McLaughlan CF (1954) Land shells originally introduced. Australian Zoologist 12: 40.
  • Newcomb W (1864) Descriptions of nine new species of Helix inhabiting California. Proceedings of the California Academy of Natural Sciences 3: 115–119.
  • Pilsbry HA (1926) The land mollusks of the Republic of Panama and the Canal Zone. Proceedings of The Academy of Natural Sciences of Philadelphia 78: 57–126, pls 129–110.
  • Pilsbry HA (1946) Land Mollusca of North America (north of Mexico), 2(1). The Academy of Natural Sciences of Philadelphia, Monographs 3: frontispiece, i–vi, 1–520.
  • Pfeiffer L (1840) Uebersicht der im Januar, Februar und März 1839 auf Cuba gesammelten Mollusken. Archiv für Naturgeschichte 6: 250–261.
  • Riedel A (1964) Zonitidae (Gastropoda) der Azoren. Boletim do Museu Municipal do Funchal 18: 5–60, 61 pls.
  • Roth B (1988 “1987”) Identities of two Californian land mollusks described by Wesley Newcomb. Malacological Review 20: 129–130.
  • Say T (1817a “1816”) Conchology. In: Nicholson W (Ed.) The First American Edition of the British Encyclopedia or Dictionary of Arts and Sciences, Comprising an Accurate and Popular View of the Present Improved State of Human Knowledge. First Edition. Vol. 2. Samuel A. Mitchell and Horace Ames, Philadelphia, 15 unnumbered pages, 4 pls.
  • Seddon MB (2008) The landsnails of Madeira. An illustrated compendium of the land snails and slugs of the Madeiran archipelago. Studies in Biodiversity and Systematics of Terrestrial Organisms from the National Museum of Wales, Biotir Reports 2: viii + 204 pp.
  • Smith BJ (1992) Non-marine Mollusca. Zoological Catalogue of Australia. AGPS, Canberra, xii + 405 pp. pp.

Cecilioides acicula

Cecilioides acicula
Cecilioides acicula, Ontario [RF].

Cecilioides (Cecilioidesacicula (O. F. Müller, 1774)
Blind Awlsnail

  • Buccinum aciculum O. F. Müller 1774: 150.
  • Many additional synonyms in Europe.

Identification. Shell very elongate. Spire tall, slender, sides almost straight. Apex bluntly rounded. Whorls flatly rounded; periphery rounded. Suture shallow, with a “false suture” below. Protoconch smooth. Teleoconch smoothish, glossy, with weak incremental lines. Aperture narrow, acute above, edentulous. Outer lip thin, simple. No umbilicus. Columella truncate below. Shell translucent, clear but opaque and whitish when weathered. Height to 5.5 mm (higher than wide).

Animal white and eyeless (blind).

This species is unique among land snails in Canada for its very slender and colourless or whitish shell.

Habitat. Mostly subterranean, this species lives underground at depths to 2 m or more, but it may also occur near the surface under debris under (such as old bricks around a greenhouse; Einsohn 1981). In Canada, so far it has only ever been found in stream drift, but presumably is living in nearby. Difficult to locate alive, shells are more likely to be found dead in stream drift (Kerney 1999). In Europe and elsewhere, it occurs in in open calcareous habitats, such as dry pastures, other grassy places, quarries, at the bases of walls, on cliffs, and in screes (Ellis 1969, Kerney 1999). It has been found in cemeteries and graves, where old bones may provide a source of calcium (Herbert & Kilburn 2004, Georges & Charlier 2010). Cecilioides acicula has been intercepted entering the USA in soil and on bulbs and other plants (Dundee 1974).

Global range. Probably originally native to the Mediterranean region; now widespread in Central and Western Europe, Asia Minor, Arabia, and North Africa; east through Crimea, Caucasus, Central Asia from Köpet Dagh to Pamiro-Alai (Kerney & Cameron 1979, Kerney et al. 1983, Kantor et al. 2010, Sysoev & Schileyko 2009); Ukrainian Ciscarpathia, and Transcarpathia (Sverlova 2006). Now introduced to South Africa, New Zealand, Australia, Bermuda, Barbados, Argentina; USA, including Hawaii, and Canada. In the continental USA, this species has been found in Maryland, New Jersey, New York (Einsohn 1981), Pennsylvania, Virginia, Florida, New Mexico, Texas, and California (Pilsbry 1946, Roth & Sadeghian 2006, Örstan 2007, NatureServe 2009).

Canadian range. Introduced to southern Ontario; although presently known only from drift of the Grand River and Bowmanville Creek, a small stream east of Toronto (Forsyth et al. 2008). Although living animals are unknown, this is not unexpected for a mostly subterranean species (Kerney 1999, Forsyth et al. 2008); established populations out of doors are likely. Specimens were recovered in drift from two separate drainages, which implies broader occurrence in southern Ontario.

Etymology. Latin, acicula, a small pin.

  • Ellis AE (1969) British snails. A guide to the non-marine Gastropoda of Great Britain and Ireland, Pleistocene to Recent. Oxford University Press, Oxford, 298 pp., 14 pls.
  • Forsyth RG, Oldham MJ, Schueler FW (2008) Mollusca, Gastropoda, Ellobiidae, Carychium minimum, and Ferussaciidae, Cecilioides acicula: distribution extension and first provincial records of two introduced land snails in Ontario, Canada. Check List 4: 449–452.
  • Georges P, Charlier P (2010) Localisation préférentielle de Cecilioides acicula (O. F. Müller, 1774) dans deux tombes hellénistiques de Plinthine (Egypte). MalaCo 6: 298-302.
  • Kerney M (1999) Atlas of the land and freshwater molluscs of Britain and Ireland. Harley Books, Colchester, Essex, U.K., 264 pp.
  • Müller OF (1774) Vermium terrestrium et fluviatilium, seu animalium Infusorium, Helminthicorum, et Testaceorum, non marinorum, succincta historia. Volumen alterum: Testacea. Heineck & Faber, Havniæ & Lipsia, xxxvi + 214 + [x] pp.
  • Sysoev A, Schileyko A (2009) Land snails and slugs of Russia and adjacent countries. Pensoft, Sofia/Moscow, 212 pp. + 142 pls.