My Publications


Forsyth, R.G., J.E. Maunder, D.F. McAlpine, and R.G. Noseworthy. 2016. Distributional status of an introduced land snail Discus rotundatus (Rotund Disc, Mollusca: Discidae) in Canada. The Canadian Field-Naturalist 130(3): 235–246.
PDF  [3,922 KB]

Abstract: First collected in North America in 1937 on the Avalon Peninsula of the Island of Newfoundland, the introduced, primarily European land snail, Discus rotundatus, has now been recorded from the Island of Newfoundland, Nova Scotia, New Brunswick, Quebec, Ontario, and British Columbia. we review all known records from Canada, demonstrate that D. rotundatus is more widespread than was previously recognized on the Island of Newfoundland, and report the first record from New Brunswick.

Discus rotundatus, the Rotund Disc, McLarens beach, Saint John, new brunswick (45°14'15.2"n, 66°06'4.2"w); collected by RGF, 24 June 2015, NBM 009144.

Discus rotundatus, the Rotund Disc, McLarens beach, Saint John, new brunswick (45°14’15.2″N, 66°06’4.2″W); collected by RGF, 24 June 2015, NBM 009144. photo: R. Forsyth.


Forsyth, R.G., P. Catling, B. Kostiuk, S. McKay-Kuja, and A. Kuja. 2016. Pre-settlement snail fauna on the Sandbanks baymouth bar, Lake Ontario, compared with nearby contemporary faunas. The Canadian Field-Naturalist 130(2): 152–157. [30 September 2016]
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Abstract: The terrestrial snail fauna in a pre-settlement soil layer, radiocarbon dated at approximately 1065–1560 years old, on the baymouth bar at Sandbanks Provincial Park, Lake Ontario, was compared with 4 nearby contemporary snail faunas from forested dunes. The pre-settlement sample differed in snail diversity, with 23 species compared with 9–20 species in contemporary samples. Six species were unique to the pre-settlement sample: Carychium exile, Euconulus fulvus, Gastrocopta armifera, Gastrocopta corticaria, Vallonia parvula, and Vertigo sp. The number of individual snails was much greater at the pre-settlement site when corrected for difference in size of sample area. The reason for the higher diversity, greater number of individuals, and different fauna associated with the pre-settlement area is unclear, but may be attributed to reduction and changes in the litter layer at the contemporary comparison sites caused by European earthworms. This work suggests that major erosional and depositional events occurred on Great Lakes shoreline dunes in the past and that these can be used to study post glacial mollusc faunas and past ecological processes, with some potentially significant results.

McAlpine, D.F., D.A.W. Lepitzki, F.W. Schueler, F.J.T. McAlpine, A.Hebda, R.G. Forsyth, A. Nicolai, J.E. Maunder and R.G. Noseworthy. 2015. Occurrence of the Chinese mystery snail, Cipangopaludina chinensis (Gray, 1834) (Mollusca: Viviparidae) in the Saint John River system, New Brunswick, with review of status in Atlantic Canada. BioInvasions Journal 5(3): 149-154. [20 July 2016]
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Abstract: The Chinese mystery snail, Cipangopaludina [=Bellamya] chinensis, is documented for the first time in the Saint John River, New Brunswick, a watercourse which drains the largest watershed in Atlantic Canada. This is the first non-native mollusc known to be established in the Saint John River system. Although significant ecosystem effects of the species seem unlikely, possible introduction of C. chinensis via boat traffic emphasizes the need for boater education combined with monitoring of the Saint John River system for potentially more troublesome non-native species, including the zebra mussel, Dreissena polymorpha. Review of published records and museum collections for Atlantic Canada show C. chinensis has been reported from 13 freshwater wetlands and waterbodies in New Brunswick, Nova Scotia and Newfoundland since 1955. The species remains extant in at least 10 of these sites and is clearly more widespread in the region than the single previously published report would suggest.

Forsyth, R.G. , & M.J. Oldham. 2016. Terrestrial molluscs from the Ontario Far North. Check List 12(3): 1881. [1 May 2016].
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From 2009–2014, incidental collections of terrestrial molluscs were made from the Far North of Ontario, Canada. Thirty-four species of terrestrial molluscs were identified from these collections, including one exotic species, Deroceras reticulatum, and three newly reported species from the Far North, Vallonia pulchella, Vertigo cf. genesii, and Gastrocopta similis. Vertigo cf. genesii is newly reported from Ontario. Some species have not been collected in Ontario for many years and some of these only once before. Subnational conservation ranks are discussed for higher-ranked species.


Telfer, A.C., et al. [111 additional authors]. 2015. Biodiversity inventories in high gear: DNA barcoding facilitates a rapid biotic survey of a temperate nature reserve. Biodiversity Data Journal 3: e6313. [30 August 2015].
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Abstract: Comprehensive biotic surveys, or ‘all taxon biodiversity inventories’ (ATBI), have traditionally been limited in scale or scope due to the complications surrounding specimen sorting and species identification. To circumvent these issues, several ATBI projects have successfully integrated DNA barcoding into their identification procedures and witnessed acceleration in their surveys and subsequent increase in project scope and scale. The Biodiversity Institute of Ontario partnered with the rare Charitable Research Reserve and delegates of the 6th International Barcode of Life Conference to complete its own rapid, barcode-assisted ATBI of an established land trust in Cambridge, Ontario, Canada.
The existing species inventory for the rare Charitable Research Reserve was rapidly expanded by integrating a DNA barcoding workflow with two surveying strategies – a comprehensive sampling scheme over four months, followed by a one-day bioblitz involving international taxonomic experts. The two surveys resulted in 25,287 and 3,502 specimens barcoded, respectively, as well as 127 human observations. This barcoded material, all vouchered at the Biodiversity Institute of Ontario collection, covers 14 phyla, 29 classes, 117 orders, and 531 families of animals, plants, fungi, and lichens. Overall, the ATBI documented 1,102 new species records for the nature reserve, expanding the existing long-term inventory by 49%. In addition, 2,793 distinct Barcode Index Numbers (BINs) were assigned to genus or higher level taxonomy, and represent additional species that will be added once their taxonomy is resolved. For the 3,502 specimens, the collection, sequence analysis, taxonomic assignment, data release and manuscript submission by 100+ co-authors all occurred in less than one week. This demonstrates the speed at which barcode-assisted inventories can be completed and the utility that barcoding provides in minimizing and guiding valuable taxonomic specialist time. The final product is more than a comprehensive biotic inventory – it is also a rich dataset of fine-scale occurrence and sequence data, all archived and cross-linked in the major biodiversity data repositories. This model of rapid generation and dissemination of essential biodiversity data could be followed to conduct regional assessments of biodiversity status and change, and potentially be employed for evaluating progress towards the Aichi Targets of the Strategic Plan for Biodiversity 2011–2020.

Forsyth, R. G., M. J. Oldham, E. Snyder, F. W. Schueler, & R. Layberry. 2015. Forty years later: distribution of the introduced Heath Snail, Xerolenta obvia in Ontario, Canada (Mollusca: Gastropoda: Hygromiidae). Check List 11(4): 1711. [7 August 2015].
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Abstract: Xerolenta obvia is a Central European land snail that is introduced to Ontario, Canada, where it was first recorded in the literature in 1975 from a single population at Bethany (City of Kawartha Lakes). Over the four decades since that publication, additional records have been found clustered near Bethany, within the City of Kawartha Lakes, and in neighbouring Peterborough County and the Regional Municipality of Durham. Two distant sites are also now known, one in rural Ottawa (southeastern Ontario), and one at Windsor, Essex County (southwestern Ontario).

Forsyth, R. G. & D. A. W. Lepitzki. 2015.Terrestrial snails (Gastropoda: Pulmonata) from Writing-on-Stone Provincial Park, Alberta, Canada. Check List 11(3): 1636. [22 April 2015].
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Abstract: There are few studies on the terrestrial molluscs of the Great Plains of Alberta. Nearly all previously published surveys have focused on the faunas of the Rocky Mountain Foothills, the Cypress Hills, the Parklands of Central Alberta, or the boreal forests. By means of hand-picking and litter samples, we surveyed for the first time the terrestrial snail fauna in the Writing-on-Stone Provincial Park, southern Alberta, Canada. From among the hoodoos (weathered rock formations) and along the cliffs on the north side of the Milk River, we found terrestrial snails at four of our five sites within the hot, dry valley of the river. Our study confirms our assumptions that the terrestrial snail fauna in these hostile habitats lacks diversity.

Forsyth, R. G., M. J. Oldham, & F. W. Schueler. 2015. Patera appressa (Say, 1821), an introduced land snail in Ontario, Canada (Mollusca: Gastropoda: Polygyridae). Check List 11(2): 1583. [17 February 2015].
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Abstract: The geographic distribution and habitat of Patera appressa (Say, 1821) in Canada are described. This is a North American land snail native to the southern Appalachians but it has been known, since 1994, from a cluster sites in Trenton, City of Quinte West, Ontario, where it is presumably introduced. It may no longer be extant at any of the known Ontario sites.

Patera appressa

Patera appressa.


Forsyth, R. G. 2015. First record of Carychium minimum Müller, 1774 in New Brunswick, Canada (Mollusca: Gastropoda: Ellobioidea). Check List 11(1): 1511. [1 January 2015].
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Abstract: The minute land snail, Carychium minimum Müller, 1774 is reported from New Brunswick, Canada. This new record further adds additional data to support the supposition that this introduced, European species is probably more widespread over temperate North America than currently known.

∗ See


Forsyth, R. G., & M. J. Oldham. 2014. Distribution of Strobilops aeneus Pilsbry, 1926, in Canada, with two new Ontario records (Mollusca: Gastropoda: Strobilopsidae). Check List 10 (2): 397–401. [14 May 2014].
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Abstract: The geographic distribution of Strobilops aeneus Pilsbry, 1926, a rare species in Canada, is reviewed and all known records are mapped. Two recent records, the only ones since 1941, are reported from the province of Ontario. One of these records represents a small range extension ca. 85 km north of the closest previous site. Specimens identified as S. aeneus from New Brunswick and Nova Scotia were re-examined and found to be another species.

∗ See

Strobilops aeneus

Strobilops aeneus. Figure 2 from Forsyth & Oldham (2014).


McAlpine, D. F., & R. G. Forsyth. 2014. Occurrence of the Copse Snail, Arianta arbustorum (Helicidae) on Prince Edward Island: an addition to the North American range of a purported potential pest. Northeastern Naturalist 21 (1): N5–N7. [2 March 2014].
→ PDF [1.38 MB].

Abstract: We report the first occurrence of Arianta arbustorum (Copse Snail) on Prince Edward Island, expanding its well-established presence in eastern Canada. Although listed as an exotic mollusc for which prevention of introduction to the US is a priority, the evidence from Canada to date suggests a low pest potential for this species. It is unlikely that eradication efforts in North America would be effective; thus, the Copse Snail may be a poor candidate for pest-prevention efforts in the US.

Forsyth, R.G. 2014. First record of Deroceras invadens Reise, Hutchinson, Schunack & Schlitt, 2011 (Gastropoda: Pulmonata: Agriolimacidae) from the island of Newfoundland, Canada. Check List 10 (1): 149–150. [21 February 2014].
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Abstract: The introduced European slug Deroceras invadens Reise, Hutchinson, Schunack & Schlitt, 2011 is here reported from St. John’s, Newfoundland. This new record is the first from the island of Newfoundland, the Canadian province of Newfoundland and Labrador, and from Atlantic Canada. It is the first verified record for this species living outside of greenhouses in eastern Canada.

Deroceras invadens


Forsyth, R. G. 2013. Towards an annotated catalogue of the terrestrial molluscs of Canada. The Malacologist 60: 22–23. [24 March 2013].


Forsyth, R. G., & P. Williston. 2012. Terrestrial snails from an urban park in Vancouver, British Columbia. The Festivus 44 (7): 77–80.
→ PDF [2.25 MB]

Snails from Queen Elizabeth Park, Vancouver, BC. 1-3, Lauria cylindrica; 4-6, Cochlicopa lubrica; 7-9, Carychium minimum; 10-12, Punctum randolphii; 13-15, Vitrea contracta; 16-18, Aegopinella nitidula; 19-21, Striatura pugetensis; 22-24, Discus rotundatus.

Snails from Queen Elizabeth Park, Vancouver, BC. 1-3, Lauria cylindrica; 4-6, Cochlicopa lubrica; 7-9, Carychium minimum; 10-12, Punctum randolphii; 13-15, Vitrea contracta; 16-18, Aegopinella nitidula; 19-21, Striatura pugetensis; 22-24, Discus rotundatus.


Grimm, F. W., R. G. Forsyth, F. W. Schueler, & A. Karstad. ‘2009’ [2010]. Identifying Land Snails and Slugs in Canada: Introduced Species and Native Genera. Canadian Food Inspection Agency, Ottawa. iv+168. [April 2010].
→ URL: english /plaveg/ pestrava/ escarge.shtml

Grimm, F. W., R. G. Forsyth, F. W. Schueler, & A. Karstad. ‘2009’ [2010]. Identification des escargots et des limaces terrestres au Canada: Espèces introduites et genres indigènes. Agence canadienne d’inspection des alimentes. Ottawa. iv+168 pp. [April 2010].
→ URL: francais/ plaveg/ pestrava/ escargf.shtml

Lepitzki, D. A. W., R. G. Forsyth, & B. M. Lepitzki. 2010. The mountainsnails of Cypress Hills, Alberta, Canada. Tentacle 18: 3–5. [January 2010].
→ URL: cowielab/ tentacle/ Tentacle_18.pdf#3

Mountainsnails, Oreohelix spp.

Small (left) and large (right) forms of Oreohelix from Cypress Hills, at the same scale. The small form is from above Reesor Lake while the large form is from the Elkwater Lake campground.


Forsyth, R. G., M. J. Oldham, & F. W. Schueler. 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 (4): 449–452. [November 2008].
→ URL: getpdf?NGD141-08

Forsyth, R. G. 2008a. Checklist of terrestrial molluscs in British Columbia. E-Fauna BC.8 pp. [Revised as needed: current version 2011].
→ URL: biodiversity/ efauna / documents/ Checklist_Terrestrial_Molluscs_BC.pdf

Forsyth, R. G. 2008b. First record of the European land snail Trochulus striolatus in British Columbia, Canada (Pulmonata: Hygromiidae). The Festivus 40 (6): 76–78. [12 June 2008].
→ PDF [758 KB]

Abstract: The European terrestrial snail Trochulus striolatus (C. Pfeiffer, 1828), found at one locality in the city of Revelstoke, is newly reported from British Columbia, Canada. This record appears to be the first time that this species has been found in western North America.


Forsyth, R. G. 2006. Terrestrial snails and slugs of British Columbia. In: Klinkenberg, Brian (Editor). 2006. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia.[]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver.
→ URL: biodiversity/ efauna/ LandSnails.html


Forsyth, R. G. 2005a. Terrestrial gastropods of the upper Fraser Basin of British Columbia. Living Landscapes, Royal British Columbia Museum, Victoria. 26 pp. → URL: upperfraserbasin/ ufb_snails/index.html

Abstract: Information on the terrestrial gastropod fauna is compiled from new or recent field collections, museum records and literature for that part of British Columbia encompassing the basin of the Fraser River north of about 52°N. Recent fieldwork (2001) has added many new locality records for a region that has received little study and has significantly improved the region’s representation of terrestrial gastropods in the collection of the Royal British Columbia Museum. At least 28 species belonging to 18 genera are recorded from 83 localities. All but three species were previously unreported in the literature from this area of British Columbia. ISBN 0-7726-5289-9.

Forsyth, R. G. 2005b. Terrestrial gastropods of the Peace River – northern Rockies of British Columbia. Living Landscapes, Royal British Columbia Museum, Victoria. 23 pp.
→ URL: prnr/prnr_snails/ index.html

Abstract: For the first time, information on the terrestrial mollusc fauna is compiled from new or recent field collections, museum records and literature for the Alberta and Liard plateaus, the northern Rocky Mountains, and much of the Cassiar and Omineca mountains of British Columbia, an area about 265,000 km2. Based on recent fieldwork (2003–2004) many new locality records are given for a poorly known region of the province. At least 23 species belonging to 13 families and 17 genera are recorded from 77 unique localities are documented in an annotated species list. Distribution of each species within the region is mapped, and locality data is tabulated in an appendix. ISBN 0-7726-5288-0.

Reise, H., J. M. C. Hutchinson, R. G. Forsyth, & T. J. Forsyth. 2005. First records of the terrestrial slug Deroceras turcicum (Simroth, 1894) in Poland. Folia Malacologica 13 (4): 177–179. → PDF [283 KB]

Abstract: Deroceras turcicum (Simroth) is reported from six woodland sites around Wałbrzych in southwest Poland. This extension of the species’ range to Poland was expected given the number of reports from adjacent areas of the Czech Republic. We collate these reports as well as local records of Deroceras praecox Wiktor, 1966, which is found in similar habitats. We briefly discuss the difficulty of distinguishing D. turcicum from Deroceras reticulatum (O. F. Müll.), with which it may also co-occur.


Forsyth, R. G. 2004a. Gastrocopta in British Columbia (Mollusca: Pulmonata: Vertiginidae). The Festivus 36 (5): 53-55 [13 May 2004]. → PDF [1.95 MB]

Abstract: Gastrocopta holzingeri (Sterki, 1889), previously known in British Columbia, Canada, by unpublished 40-year-old museum records, was rediscovered in southeastern B.C. in 2002, and its habitat is described. References in the literature to G. pentodon (Say, 1822) in British Columbia are thought to be in error.

Forsyth, R.G. 2004b. Land Snails of British Columbia. Royal British Columbia Museum Handbook. Royal BC Museum, Victoria. iv + 188 pp. +[8] pls.
→ More information


Forsyth, R. G. 2003a. Northern range extension for Assiminea translucens (Carpenter, 1864). The Festivus 35 (2): 17–18 [13 February 2003].
→ PDF [457 KB]

Forsyth, R.G. 2003b. Key to slugs of British Columbia. Botanical Electronic News 320.
→ URL: cas/ botany-micro/ ben/ ben320.html


Forsyth, R. G. ‘2001’ [2002]. New records for land snails from the mountains of northwestern British Columbia. The Canadian Field-Naturalist 115 (2): 223–228. [14 December 2002].

Abstract: Terrestrial gastropod faunas of vast areas of northern and central British Columbia are extremely poorly known. I record new distributional records of Punctum randolphii (Dall, 1895), Microphysula cookei (Pilsbry, 1922), Pristiloma arcticum (Lehnert, 1884), Vertigo columbiana (Pilsbry & Vanatta, 1900) and other land snails from the Babine and Bulkley Ranges, Nechako Plateau, and Boundary Range of northwestern British Columbia. Records of Punctum randolphii andVertigo columbiana are the first higher elevation localities in British Columbia.Pristiloma arcticum was collected from one site in the Babine Mountains and is newly recorded from the province. Microphysula cookei, previously known only from southern British Columbia and adjacent Washington, occurs north to the Babine and Hazelton Ranges, Nechako Plateau, and Boundary Range. While sharing many species in common, the mountain snail fauna differed from that of the adjacent Bulkley Valley by the inclusion of “coastal” and montane elements. Absent from the drier valley floor, Punctum randolphii, Microphysula cookei, Vertigo columbiana and Vespericola columbianus are considered coastal species whose distributions extend far inland along climatically favourable corridors. → PDF [6.89 MB]

COSEWIC. 2002. COSEWIC assessment and status report on the Warty Jumping-slug,Hemphillia glandulosa, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 19 pp.
[Status report prepared by R.G. Forsyth and K.E. Ovaska.]

COSEWIC. 2002. COSEWIC assessment and status report on the Dromedary Jumping-slug, Hemphillia dromedarius, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 21 pp.
[Status report prepared by K.E. Ovaska and R.G. Forsyth.]

COSEWIC. 2002. COSEWIC assessment and status report on the Oregon forestsnail,Allogona townsendiana, in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 20 pp.
[Status report prepared by R.G. Forsyth and K.E. Ovaska.]

COSEWIC. 2002. COSEWIC assessment and status report on the Puget Oregonian snail, Cryptomastix devia, in Canada. vi + 20 pp.
[Status report prepared by K.E. Ovaska and R.G. Forsyth.]


Forsyth, R. G. 2001a. Re-identification of slugs from seabird nesting burrows off the west coast of Vancouver Island. The Festivus 33 (1): 9–10 [11 January 2001].

Abstract: Two species of terrestrial slugs were collected from driftwood and the nesting burrows of Leach’s storm-petrels, Oceanodroma leucorhoa (Vieillot, 1818), on a small island off the west coast of Vancouver Island in the late 1960s. The species were identified and published as Ariolimax columbianus (Gould, 1851) and Deroceras reticulatum (Müller, 1774). However, based on external morphology and anatomy of preserved material and remarks on the pigmentation of the living animal, the record is re-identified as Prophysaon foliolatum (Gould, 1851). Although incorrectly determined, the original observations of P. foliolatum from storm-petrel burrows are noteworthy because of the unusual slug – bird association and habitat. → PDF [1.5 MB]

Forsyth, R. G. 2001b. A note on the distribution of Striatura pugetensis in British Columbia. The Festivus 33 (5): 57–58 [10 May 2001].

Forsyth, R. G. 2001c. First records of the European land slug Lehmannia valentiana in British Columbia, Canada. The Festivus 33 (7): 75–78 [12 July 2001].

Abstract: The synanthropic slug, Lehmannia valentiana (Férussac, 1821), is recorded in British Columbia for the first time. The identification of an adult specimen from Victoria, Vancouver Island, is confirmed by dissection. Additional records, based on undissected immature specimens, photographs and sightings, are known from nearby sites on southern Vancouver Island and from an island in the Strait of Georgia. → Full text here

Forsyth, R.G., & T. Forsyth. 2001. A note on Mercenaria mercenaria in British Columbia. The Festivus 33 (8): 85 [9 August 2001]. → PDF [8.05 MB]

Forsyth, R.G., J.M.C. Hutchinson, & H. Reise. 2001. Aegopinella nitidula (Draparnaud, 1805) (Gastropoda: Zonitidae) in British Columbia — first confirmed North American record. American Malacological Bulletin 16 (1/2): 65–69. [7 November 2001].

Abstract: The European land snail, Aegopinella nitidula (Draparnaud, 1805), is reported for the first time from British Columbia, from three sites in the city of Vancouver. These new records are the only documentation of the species in North America, except for two old records that are probably erroneous and have been ignored in recent literature. Comparisons are made between A. nitidula and similar native and introduced species. Information about its ecology in Europe is summarized. →  PDF  [1.69 MB]


Forsyth, R. G. 2000. The land snail Cryptomastix germana (Gastropoda: Polygyridae) in the Queen Charlotte Islands, British Columbia: a range extension north from Vancouver Island. The Canadian Field-Naturalist 114 (2): 316–317 [7 September 2000]. → PDF [1.1 MB]

Abstract: The coastal land snail Cryptomastix germana, not previously known to occur north of Vancouver Island, is reported from the Queen Charlotte Islands, British Columbia.

Reise, H., J.M.C. Hutchinson, R.G. Forsyth, & T.J. Forsyth. 2000. The ecology and rapid spread of the terrestrial slug Boettgerilla pallens in Europe with reference to its recent discovery in North America. The Veliger 43 (4): 313–318 [2 October 2000]. → PDF [1.4 MB]

Abstract: The terrestrial slug Boettgerilla pallens Simroth, 1912, is reported from two sites on Vancouver Island, British Columbia, the first records for this Palaearctic species in America. This paper describes how to recognize the species, and summarizes European studies of its ecology. It is unusually wormlike in appearance, lives mostly underground, and occurs in a very wide range of habitats. This century the species has spread remarkably far and fast across Europe from the Caucasus. This is demonstrated by a table of first occurrences in each country, and by three case studies of spread within Great Britain, Belgium, and north-west Austria. We predict that it will spread rapidly in North America, and may already occur more widely, but there is no evidence that it will become an important pest.


Forsyth, R. G. 1999a. Forsyth, R. G. 1999a. Lindeman Lake, British Columbia, type locality of Zonitoides randolphi Pilsbry. The Veliger 42 (3): 286. [1 July 1999].

Forsyth, R. G. 1999b. Terrestrial gastropods of the Columbia Basin, British Columbia. Living Landscapes, Royal British Columbia Museum, Victoria. Available in HTML and PDF format.
→ Update here (July 28, 2006). URL: cbasin/ molluscs/ contents.html

Forsyth, R. G. 1999c. Distributions of nine new or little-known exotic land snails in British Columbia. The Canadian Field-Naturalist 113 (4): 559–568. [17 December 1999].

Abstract: Introduced species of terrestrial molluscs of British Columbia were collected between 1989 and 1998. New locality records and expanded distributions are documented for seven introduced land snails: Lauria cylindracea (Chrysalis Snail), Vallonia pulchella (Lovely Vallonia), Oxychilus alliarius (Garlic Glass-snail), O. cellarius (Cellar Glass-snail), O. draparnaudi (Dark-bodied Glass-snail), Cepaea nemoralis (Grovesnail) and Helix aspersa (Brown Gardensnail). Two other species, Vallonia excentrica (Iroquois Vallonia), and Vitrea contracta (Contracted Glass-snail) are reported from British Columbia for the first time. About 25% of the terrestrial mollusc species in the province are exotic. Mechanisms of introduction include transport on nursery plants and on salvaged bricks. Potential impacts on native fauna include predation by Oxychilus.