Xerolenta obvia (Menke, 1828)
- Helix neglecta Hartmann 1821: 226, non Helix neglecta Draparnaud, 1805.
- Helix obvia Menke 1828: 13, nomen novum pro Helix neglecta Hartmann 1821.
- Additional synonyms in the European literature.
Identification. Shell strongly flattened-heliciform, with a very low-conic spire, a little variable in height. Suture strongly indented. Whorls 4¾–5¼, convex, last whorl rather rapidly enlarging and descending when shell full-grown. Periphery of last whorl rounded, medial. Protoconch smooth. Teleoconch with weak growth lines. Periostracum inconspicuous (translucent). Aperture subovate, without teeth, wider than high. Peristome viewed from side prosocline and straight to arched. Lip not thickened; baso-columellar lip and lower portion of palatal lip very slightly recurved. Low callus rib present inside aperture, well back from lip. Parietal callus inconspicuous, glazed, transparent. Umbilicus moderately large, ca ¼ of shell width. Shell opaque, white, creamy-white, or grey-white, usually with darker brown or black bands; usually with a single broad dark brown spiral band above the periphery and up to 6 paler, less distinct bands below that may be broken up into a series of dots or coalescing; protoconch and first teleoconch whorl brown. Aperture and peristome creamy-white, with the exterior pigmentation showing. Width to 12–20 mm (higher than wide).
Animal pale tan, with darker tentacles.
The rather large size, white shell, usually with brown bands, depressed form and wide umbilicus distinguish this species from others here.
Habitat. Roadsides and other open, calcareous, disturbed area with grass and weeds. Climbing and aestivating above the ground, on vegetation. Usually in dense aggregations of many individuals and often seen by the thousands, both on the ground and aestivating on the stems of plants. Populations can be large, sometimes covering several hectares. Dense colonies of snails are known in Europe as well.
Biology. A study in Greece reported that this species lives for one or two years, depending on climatic conditions, but soon die after reproducing (Larazidou & Chatziioannou 2005). Large numbers of dead shells are normal at sites occupied by this species.
Global range. Central Europe, west to southern France, east to Ukraine and European Turkey, and south to Greece (Kerney & Cameron 1999, Schütt 2005). Introduced to North America: Michigan, Ontario, and Montana (Robinson & Slapcinsky 2005, Forsyth et al. 2015).
Canadian range. Introduced rather widely to southern Ontario: Windsor area east to near the Ottawa region (Forsyth et al. 2015). This species was first reported from near Bethany, (now within the City of Kawartha Lakes) where it was found in 1969; however, it has apparently been there for decades earlier (Grimm & Wiggins 1975).
Etymology. Latin: obvius, commonplace.
Remarks. Xerolenta obvia pappi (Schütt, 1962), is subspecies from northern Greece, Bulgaria, and western Turkey (Schütt 2005, Bank and Neubert 2017). Having a strongly keeled shell, it was originally described as separate species (Shütt 1962). Hausdorf (1988) later treated it as a subspecies of X. obvia on account of the identical anatomy in these taxa and the presence of individuals with transitional conchological characters. However, the taxonomic status of this and other subspecies remains uncertain: are these variations of a single, polymorphic species or specifically distinct (Irikov & Eröss 2008)? Canadian populations would belong to the nominotypical subspecies, X. obvia obvia if subspecies were recognized.
- Bank RA, Neubert E (2017) Checklist of the land and freshwater Gastropoda of Europe [last update 15 July 2017]. MolluscaBase. http://www.marinespecies.org/aphia.php?p=sourcedetails&id=279050. Accessed on: 2020-12-11.
- Forsyth RG, Oldham MJ, Snyder E, Schueler FW, Layberry R (2015) Forty years later: distribution of the introduced Heath Snail, Xerolenta obvia in Ontario, Canada (Mollusca: Gastropoda: Hygromiidae). Check List 11: 1711.
- Grimm FW, Wiggins GB (1975 “1974”) Colonies of the European snail Helicella obvia (Hartmann) in Ontario. The Canadian Field-Naturalist 88: 421–428.
- Hartmann JDW (1821) System der Erd- und Flußschnecken der Schweiz. Mit vergleichender Aufzählung aller auch in den benachbarten Ländern, Deutschland, Frankreich und Italien sich vorfindenden Arten. Neue Alpina, eine Schrift der Schweizerischen naturgeschichte, Alpen- und Landwirthschaft gewiedmet 1: 194–268, pl. 191–192.
- Hausdorf B (1988) Zur Kenntnis der Systematischen Beziehungen einiger Taxa der Helicellinae Ihering 1909. Archiv für Molluskenkunde 119: 9–37.
- Irikov A, Erőss ZP (2008) An updated and annotated checklist of Bulgarian terrestrial gastropods (Mollusca: Gastropoda). Folia Malacologica 16: 199–207.
- Lazaridou M, Chatziioannou M (2005) Differences in the life histories of Xerolenta obvia (Menke, 1828) (Hygromiidae) in a coastal and a mountainous area of northern Greece. Journal of Molluscan Studies 71: 247–252.
- Kerney MP, Cameron RAD (1999) Guide des Escargots et Limaces d’Europe. Translated by A Bertrand. Delachaux et Niestlé, Lausaane, Switzerland, 370 pp., 28 pls.
- Menke K (1828) Synopsis methodica, Molluscorum generum omnium et specierum earum, quae in Museo Menkeana adservantur; cum synonymia critica et novarum specierum diagnosibus. Henrici Gelpke, Pyrmonti, xii + 91 pp.
- Robinson DG, Slapcinsky J (2005) Recent introductions of alien land snails into North America. American Malacological Bulletin 20: 89–93.
- Schütt H (1962) Eine gekielte Helicella aus Thrazien. Archiv für Molluskenkunde 91: 151–156.
- Schütt H (2005) Turkish land snails, 4th ed. Verlag Natur & Wissenschaft, Solingen, Germany, 559 pp.