Trochulus striolatus

Trochulus striolatus (C. Pfeiffer, 1828)
Strawberry Snail

  • Cochlea rufescens Mendes Da Costa 1778: 80, pl. 4, fig. 6.
  • Helix striolatus C. Pfeiffer 1828: 28, pl. 6, fig. 8.
  • Helix montana C. Pfeiffer 1828: 33, pl. 6, fig. 9.
  • Helix danubialis Clessin 1874: 184, pl. 8, fig. 4.
  • Helix altenana Klees in Locard 1882: 79.
  • Helix manchesteriensis “Bourguignat” Locard 1888: 324.
  • Helix abludens Locard 1888: 334.
  • Helix rufescentella Locard 1894: 128–129.
  • Helix britannica Westerlund 1894: 164.
  • Helix montana var. juvavensis Geyer 1914: 276.
  • Additional synonyms and suspected synonyms in the European literature.
Trochulus striolatus; Revelstoke, BC.

Identification. Shell depressed-heliciform. Spire low-conic. Whorls ca 6, obtusely angular at periphery, slowly enlarging, but then more rapidly in the final whorl; last whorl slightly descending when shell full-grown. Periphery of last whorl obtusely angular, medial. Suture rather deep. Aperture broadly lunate, edentulous. Lip not thickened; basal and columellar lip narrowly expanded; low, white callus or rib behind baso-columellar lip. Teleoconch irregularly striate, with a periostracum; periostracal hairs usually absent in adults. Shell thin, matte, reddish brown or yellowish brown, usually with a faint, pale band at periphery; lip white. Width to 8.5–14 mm (wider than high).

Animal variable in colour; the more common paler morphs have scattered brown or black blotches, while the less common darker morphs are solid black and with slightly darker shells (Oughton 1938).

This species is larger than Trochulus hispidus, with the periostracal hairs always absent in adults, the periphery subangular with a pale band.

Trochulus striolatus; Revelstoke, BC.

Habitat. On waste ground, along roads, around the edges of fields and woods, in disturbed woods, in abandoned quarries; under decaying leaves and vegetation, woody debris, and garbage.

This species is gregarious, frequently found in large numbers. Oughton (1938) recorded over 800 individuals within a 12 sq. ft [about 1.1 m2) area but this was probably an under-estimate because young individuals were likely missed.

Canadian range. Introduced. Southern Ontario and southern Quebec, Nova Scotia (old record), and Newfoundland (Pilsbry 1939, Brooks & Brooks 1940, Dundee 1974). An early introduction, this species was first reported from Quebec over 150 years ago by Whiteaves (1861). British Columbia: at Revelstoke (Forsyth 2008); it was collected again at the same site and a few kilometres away at other sites in 2018 (unpubl. data). The Revelstoke sites are the only places in western North America where this species is currently known.

Etymology. Latin: striolatus, furrowed.

Remarks. Like T. hispidus, this species exhibits much variation from place to place (Forcart 1962, Proćków 2009). Some authors recognized subspecies by the basis of shell forms and geography (e.g., Falkner et al. 2002), but most of these were believed to be synonyms (Proćków 2009). Subspecies were synonymised by Proćków et al. (2017), who found that shell size and other characters were correlated to altitude and climate. If subspecies are warranted, it is unclear to which subspecies Canadian populations might belong.

  • Clessin S (1874) Die Gruppe Fruticicola Held des Genus Helix L. Studien über Helix-Gruppe Fruticicola Held. Jahrbücher der Deutschen Malakozoologischen Gesellschaft 1: 177–194, 305–336.
  • Falkner G, Ripken TEJ, Falkner M (2002) Mollusques continentaux de France. Liste de Référence annotée et Bibliographie. Patrimoines naturels 52: 1–350.
  • Forcart L (1962) New researches on Trichia hispida (Linnaeus) and related forms. Proceedings of the First European Malacological Congress, 79–93.
  • Forsyth RG (2008) First record of the European land snail Trochulus striolatus in British Columbia, Canada (Pulmonata: Hygromiidae). The Festivus 40: 76–78.
  • Geyer D (1914) Über die Molluskenfauna des Salzkammergutes und ihre Beziehungen zum Diluvium in Schwaben. Verhandlungen der kaiserlich-königlichen zoologisch-botanischen Gesellschaft in Wien 64: 270–289.
  • Locard A (1882) Prodrome de la malacologie française. Catalogue général des mollusques vivants de France: mollusques terrestres, des eaux douces et des eaux saumâtres. Georg/Baillière, Lyon/Paris, 462 pp.
  • Locard A (1888) Contributions à la faune malacologique française. XII. Études critiques sur les Helix du groupe de l’Helix rufescens Pennant (Helix striolata, H. rufescens, H. montana, H. cælata, H. circinata, H. clandestina). Annales de la Société Linnéenne de Lyon (Nouvelle Série) 34: 309–370.
  • Locard A (1894) Conchyliologie française. Les coquilles terrestres de France: description des familles, genres et espèces. Avec 515 figures dessinées d’après nature et intercalées dans le texte. B. Baillière, Paris, 370 pp.
  • Mendes Da Costa E (1778) Historia naturalis testaceorum Britanniæ, or, the British conchology; containing the descriptions and other particulars of natural history of the shells of Great Britain and Ireland: illustrated with figures. In English and French. Millan, White, Emsley & Robson, London, xii + 254 + vii + [1] pp., 17 pl. pp.
  • Oughton J (1938) Notes on Hygromia striolata (Pfr.) at Toronto, Canada. The Nautilus 51: 137–140.
  • Pfeiffer C (1828) Naturgeschichte deutscher Land- und Süsswasser-Mollusken. Dritte Abtheilung. Landes-Industrie-Comptoir, Weimar, vi + 84 pp, 8 pls.
  • Proćków M (2009) The genus Trochulus Chemnitz, 1786 (Gastropoda: Pulmonata: Hygromiidae)—a taxonomic revision. Folia Malacologica 17: 101–176.
  • Westerlund CA (1894) Specilegium malacologicum. Neue Binnen-Conchylien aus der Paläarktischen Region. Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft 26 (9/10): 163–177, 190–205.