Distributional Status of an Introduced Land Snail Discus rotundatus (Rotund Disc, Mollusca: Discidae) in Canada RobeRt G. F oRSyth 1, 2, 5 , John e. M aunDeR 3,DonaLD F. M CaLpIne 1, and RonaLD G. n oSewoRthy 4

1new brunswick Museum, 277 Douglas avenue, Saint John, new brunswick e2K 1e5 Canada 2Royal british Columbia Museum, 675 belleville Street, Victoria, british Columbia V8w 9w2 Canada 3p.o. box 250, pouch Cove, newfoundland and Labrador a0a 3L0 Canada 4School of Marine biomedical Science, Jeju national university, Jeju 690-756 Republic of Korea 5Corresponding author: [email protected]

Forsyth, Robert G., John e. Maunder, Donald F. Mcalpine, and Ronald G. noseworthy. 2016. Distributional status of an intro - duced land snail Discus rotundatus (Rotund Disc, Mollusca: Discidae) in Canada. Canadian Field-naturalist 130(3): 236–247. First collected in north america in 1937 on the avalon peninsula of the Island of newfoundland, the introduced, primarily euro - pean l and 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. Key words: Discus rotundatus ; Mollusca; terrestrial snail; gastropod; new provincial record; new brunswick; newfoundland and Labrador; biogeography Introduction database), ohio (GbIF 2015), Michigan (Carnegie Mu - Discus rotundatus (Müller, 1774), the Rotund Disc, seum of natural history database), Mississippi, ten - is a distinctive land snail that is native to the euro- nessee, Georgia, and alabama (national Museum of Mediterranean region, where it is widespread, almost natural history, Smithsonian Institution database; Car - ubiquitous, and commonly synanthropic (taylor 1909; negie Museum of natural history database). umiński 1962; Kerney and Cameron 1979; Gitten - In Canada, D. rotundatus has been found in six prov - berger et al. 1984; Kerney 1999; wiktor 2004; wel - inces (Figure 1). here, we report and discuss both old ter-Schultes 2012; wiese 2014). It reaches its eastern and new records from atlantic Canada, including the limit in Latvia, belorussia, and ukraine, including first record for the species from new brunswick, and Crimea (umiński 1962; Sysoev and Schileyko 2009). review all other Canadian records. outlying occurrences in algeria (umiński 1962), as this small species (diameter up to 6.2 mm in Cana - well as turkey (Örstan 2003; Örstan and Kösemen dian material; elsewhere to 7 mm [e.g., umiński 1962; 2011), Malta (Giusti et al. 1995), the azores (back - wiese 2014]; or even 8 mm [ fide Germain 1930]) is dis - huys 1975; Martins 1995; Cameron et al. 2001), and tinguished by a flattened, opaque, ribbed, grey-brown Madeira (Seddon 2008) are almost certainly introduc - shell that is usually marked by somewhat regularly tions. In the Southern hemisphere, D. rotundatus is in - spaced, red-brown blotches (Figures 2 and 3a,b). al - troduced to the vicinity of Melbourne, australia (GbIF though taylor (1909) reported that these blotches are 2015) and western Cape province, South africa (her - occasionally absent, we have not seen any specimens bert 2010). from Canada or europe that lack this characteristic. In the united States, where D. rotundatus is also Örstan (2012) claimed that his specimen lacked spots, introduced, the species was first recorded in Massachu - but unusually pale blotches are present in his figured setts in 1939 (Clench and banks 1939; pilsbry 1948) specimen. Several other species of Discus occur in and has since been found in Maine (Gleich and Gilbert Canada ( D. whitneyi, D. catskillensis, D. patulus, and 1976; Martin 2000), Vermont (Lee 2009), new york D. shimekii ), but none has red-brown blotches. the (Jacobson 1951; Jacobson and emerson 1961), new only other Canadian land snail species with a similar Jersey (Freed 1953; Jacobson 1954; Steury and Steury colour pattern is the native Anguispira alternata , but it 2011), pennsylvania (pearce 2008, 2015; Steury and is much larger (up to about 25 mm; pilsbry 1948), with Steury 2011), washington, DC (Steury and Steury 2011), less tightly coiled whorls (Grimm et al. 2010). at matu - washington state (Forsyth 2004), oregon (anonymous rity, both species have about 5½ to 6 whorls (counted 2015), and California (Roth 1982; hertz 1996). Dundee by the method used by Kerney and Cameron [1979]), (1974) summarized some of the records from the east - but D. rotundatus is much less than half the size of A. ern united States. additional unpublished records exist alternata even when it attains the maximum number for Connecticut (Carnegie Museum of natural history of whorls . Discus rotundatus was treated comprehen -

236 ©The Ottawa Field-Naturalists’ Club (2016) 2016 FoRSyth ET AL .: DISCUS ROTUNDATUS In CanaDa 237

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FIGuRe 1. Distribution of Discus rotundatus , the Rotund Disc, in north america. Shading indicates provinces and states where it has been introduced. black circles show Canadian occurrences: 1, Vancouver; 2, toronto; 3, Montreal; 4, Saint John; 5, halifax; 6, brigus, Ferryland, and St. John’s. white circles show united States occurrences according to Jacobson (1951,1952); Freed (1953); Dundee (1974); Gleich and Gilbert (1976); Roth (1982); hertz (1996); pearce (2008); Lee (2009); Steury and Steury (2011); anonymous (2015); GbIF (2015); database records of Carnegie Museum of natural history, Field Museum, national Museum of natural history (Smithsonian Institution), Royal british Columbia Museum, R. Forsyth, and R. noseworthy.

FIGuRe 2. 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. sively by taylor (1909), as Pyramidula rotundata , and species, associated with rotting wood and living in was compared with other european representatives of leaf litter, but that it has invaded anthropogenic habi - the genus Discus by umiński (1962). tats (such as parks and ruins). the same author con - the lifestyle, population dynamics, and ecology of firmed its known highest altitude at 2700 m above D. rotundatus were described by Kuźnik-Kowalska sea level in the european alps. boycott (1929, 1934) (1999), who wrote that is was originally a woodland described the species as a generalist, living wherever 238 the CanaDIan FIeLD -n atuRaLISt Vol. 130

FIGuRe 3. Live examples Discus rotundatus, the Rotund Disc, newfoundland and Labrador . a. near wharf at brigus, 10 May 2008; b. Masonic terrace, St. John’s, 22 august 2014; C. anglican Cemetery, brigus, 25 May 2008, with terrestrial isopods Oniscus asellus Linnaeus, 1758 and Porcellio scaber Latreille, 1804. photos: J. e. Maunder. there is sufficient moisture and shelter, and as one of ince, all of them on the eastern avalon peninsula: Fer - the “forty or so [british] species to which we cannot ryland (2 sites), brigus (3 sites; Figure 4a), and St. assign specific habitats” (boycott 1929: 213). John’s (8 sites; table 1). Nova Scotia Materials and Methods Discus rotundatus was first reported from nova Sco - we consulted the following institutional collections, tia in simple lists of species without supporting data, where material exists or was deposited: new bruns - including specific locality (Davis 1990, 1992). an ear - wick Museum (nbM), Saint John; Royal british Co - lier list by the same author did not include this species lum bia Museum (RbCM), Victoria; Canadian Museum (Davis 1985). the nSM does have one lot of D. ro tun - of nature (CMnML), Gatineau, Quebec; nova Scotia datus from halifax, from 200 0, which post-dates Davis’ Museum (nSM), halifax; and the Rooms provincial abovementioned publications, but no earlier-collected Museum (formerly the provincial Museum of new - material is held in the collection. In 2010, DFM made foundland and Labrador; nFM), St. John’s. other col - one additional collection, from halifax (table 1). lections consulted, where no material exists, were Roy - al ontario Museum, toronto, and Manitoba Museum, New Brunswick winnipeg. we also consulted the private collection of Discus rotundatus was unknown from new bruns - George p. holm (new westminster, british Columbia), wick until 2015 when RGF found it in Saint John and undertook a survey of the literature. because of (table 1). the distinctiveness of D. rotundatus, we did not consid - Quebec er it critical to verify all collections, although we did Örstan (2012) reported D. rotundatus from Mont verify most (table 1). Royal, Quebec, a Montreal municipal park established Individually, we have made a number of new collec - in 1876. RGF provisionally identified material based on tions during general reconnaissance fieldwork for ter - an image of Örstan’s material (Grimm et al. 2010), with restrial molluscs over many years. Specimen and data Örstan (2012) stating that shells lacked the character - collection procedures varied. Most material was col - istic reddish marks of the species. Örstan (2012) col - lected by hand, killed in alcohol, removed and allowed lected five shells in 2008 (live) and 2011 (fresh dead), to dry, and then stored as dry shells. Some of the mate - reporting that casual searches did not reveal D. rotun - rial held at nFM has been fixed and stored in ethanol. datus elsewhere on Mont Royal. More recently, DFM all known records and voucher specimens of D. collected 44 live D. rotundatus shells at two addition - rotundatus , from Canada, are listed in table 1. al sites from under downed woody debris in mature Red oak ( Quercus rubra L.)–Sugar Maple ( Acer saccharum Results Marshall) forest on Mont Royal during 60 minutes of Newfoundland and Labrador searching. each of these new sites is about 0.5 km from brooks and brooks (1940) reported the first con - the site reported by Örstan (2012) and together with the firmed north american collection of D. rotundatus , ease of collection, suggests abundance, widespread oc - made in 1937 from the ruins of an old Church of eng - currence, and persistence of D. rotundatus on Mont land church in Ferryland, on the avalon peninsula of Royal (table 1). nearly all of the shells in the recent the Island of newfoundland. as a result of subsequent D. rotundatus collections from Quebec are clearly dis - collecting, primarily by JeM and RGn, three general tinguished by the characteristic reddish marks of the occurrence groupings are currently known in the prov - species. 2016 FoRSyth ET AL .: DISCUS ROTUNDATUS In CanaDa 239 - a n a C

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FIGuRe 4. examples of the varied habitat of the Rotund Disc, Discus rotundatus , in Canada. a. brigus, newfoundland and Labrador; b. Mont Royal, Montreal, Quebec. photos: J. e. Maunder (a) and D. F. Mcalpine (b).

Ontario also possible that this specimen was wrongly labelled Discus rotundatus was first found in ontario by D. at some time, as is often the case in old shell collections. M. wood and associates. Material in the CMnML col - although these two records provide the tantalizing pos - lection is from the Rosedale Ravine and was collect - sibility that D. rotundatus is, or was, present on Vancou- ed in 1954 and 1970. Recently, DFM re-collected the ver Island, this species remains unconfirmed from there. species from this ravine, where it is widespread and Discus rotundatus is, however, present in the City of abundant (table 1). the discovery of this species in Vancouver. From Queen elizabeth park, holm (2010) beach drift at bluffers park, toronto, was noted by reported the first recent, confirmed records from british Karstad (1995). Columbia. Forsyth and williston (2012) independently the late F. w. Grimm (Grimm 1996; Grimm et al. found the species in the same park and at another site, 2010) reported this species from ottawa. RGF has re - on east 31st Street, about 1 km away. Since then, two viewed Grimm’s collections, now in CMnML (includ - additional sites (at least 5.5 km southeast of the east ing those in the backlog, as well as his final collection 31st Street site) were found in two conjoining parks, donated to the museum after his death) and has not everett Crowley park (holm 2012) and adjacent Cham - located any D. rotundatus material from that city. plain heights park, with collection sites probably less British Columbia than 500 m apart (table 1). Discus rotundatus was undetected in british Colum - bia for many years, and even extensive surveys in urban Discussion areas of Vancouver and Victoria by Forsyth (1999) although long known to be introduced in north failed to find it. Forsyth (2004) included it in the prov - america since at least the first records from new - ince based on an unpublished museum lot (CMnML foundland in the 1930s (brooks and brooks 1940), 91841) purportedly collected at esquimalt (a suburb of D. rotundatus has not yet become as generally wide - Victoria), Vancouver Island, on 20 December 1954. spread and common as certain other introduced euro - however, Forsyth and williston (2012) contacted the pean snails, such as Oxychilus spp., and occurrences collector of this material, D. M. wood, who was ada - — as far as we know — still seem to be clustered. Giv - mant that he could not have collected those specimens en the frequency of interceptions of D. rotundatus , by on Vancouver Island at that time (D. M. wood, person - the united States plant protection and Quarantine Divi - al communication). assuming that the date and collec - sion (1.08% of all interceptions between 1993 and 1998; tor’s name are correct, those specimens seem con - Robinson 1999), it is surprising that the species is not temporaneous with others collected by D. M. wood in much better established on this continent. toronto the preceding year; thus, it is possible that they In newfoundland, D. rotundatus has persisted for at were also from toronto and that the locality data were least 79 years. however, it remains restricted to just in correct. we suspect, then, that this series of specimens three clusters of occurrences: at Ferryland; in brigus and the data have become wrongly associated. (Figure 4a), where it is generally common; and in however, there is also a single specimen of D. St. John’s. rotundatus (CMnML 097166) from “Victoria” (with In british Columbia, fieldwork by RGF in urban no additional data). presumably this material is from areas of Vancouver and Victoria and their suburbs (For - the a. hanham collection and, if correct, would seem to syth 1999) failed to locate this species until recently, pre-date the discovery of this species in newfoundland, and then only at two sites in Vancouver. we do not because hanham died in 1944 after dispersing his mol - expect that these occurrences represent recent introduc - lusc collection in 1940 (Drake 1963). however, it is tions, but rather that the species was missed in prior 2016 FoRSyth ET AL .: DISCUS ROTUNDATUS In CanaDa 245

years. Discus rotundatus is not uncommon at Queen In Canada, D. rotundatus is found in habitats (Figure elizabeth park, but was not found during multiple vis - 4a,b) almost as varied as those in europe, confirming its to a different area of the same park while looking boycott’s (1929, 1934) view that it may live anywhere for Aegopinella nitidula , another introduced snail (For- there is shelter and moisture. syth et al. 2001). If D. rotundatus were more gener al - ly distributed, it would have been encountered along Acknowledgements with the dozen introduced species of snails found in George holm (new westminster, british Columbia), british Columbia over the last couple of decades (in - Frederick Schueler (bishops Mills, ontario), and pat - cluding some new provincial, Canadian, or north amer - rick williston (Smithers, british Columbia), as well ican records; e.g., Forsyth 1999, 2008; Forsyth et al . as John M. C. hutchinson and heike Reise (Sencken - 2001). here, as perhaps elsewhere in Canada, this spe - berg Museum für naturekunde Görlitz), shared data cies may have a very local distribution, perhaps con - and/or specimens with us or collected specimens. na - fined to a few hundred square metres. thalie Djan-Chékar (the Rooms provincial Museum), we do not have much data on D. rotundatus from Jean-Marc Gagnon (Canadian Museum of nature), ontario or the other provinces where it has been found, heidi Gartner (Royal british Columbia Museum), an - but it is noteworthy that, although several collectors drew hebda (nova Scotia Museum), Robert hershler have been active in ontario over many years (F. w. (national Museum of natural history, Smithsonian In - Grimm, F. w. Schueler, Michael J. oldham, and RGF) sti tution), Janis Klapecki (Manitoba Museum), timothy and together have examined at least several hundred pearce (Carnegie Mu seum of natural history), Mary sites, the species has not been found outside toronto Sollows (new bruns wick Museum), and Maureen Zu - and the Rosedale Ravine. although Grimm said that he bowski (Royal ontario Museum) provided informa - had found it in ottawa, we found no evidence support - tion on, access to, or assisted in depositing specimens ing this claim. our new record of D. rotundatus from into the collections under their care. we thank them all halifax, nova Scotia, suggests that the species could for their assistance. we are especially grateful to tim - othy pearce for sharing unpublished records from his be more generally spread, especially if Davis’ earlier private collection (now in the Carnegie Museum of nat - mention of the species from nova Scotia represents ural history) and D. Monty wood (ottawa, ontario) one or more undocumented finds from the province. for discussion of the esquimalt, british Columbia rec - the mode and source of terrestrial mollusc intro - ord. Finally, we thank the two reviewers, Jochen Ger - ductions are little known (Grimm et al. 2010), but D. ber and timothy pearce, for their valuable comments rotundatus has likely been introduced to north amer - on the manuscript. ica on a number of occasions. all three occurrence clus ters in newfoundland are closely associated with Literature Cited saltwater harbours, which at least in years past have Anonymous. 2015. Discus rotundatus (Müller, 1774) Rotund received significant trans-atlantic sea traffic. transpor - Disc. Jacksonville Shell Club, Jacksonville, Florida, uSa. tation via ships’ ballast material is possible. In this accessed 17 october 2015. http://www.jacksonvilleshells respect, Lindroth (1957) reported D. rotundatus at ship .org/rotut.htm. ballasting places at Dartmouth, england. Backhuys, W. 1975. Zoogeography and taxonomy of the however, the plant trade is recognized as a major Land and Freshwater Molluscs of the azores. backhuys vector for introductions of terrestrial snails (bergey et and Meesters, amsterdam, netherlands. Bergey, E. A., L. L. Figueroa, C. M. Mather, R. J. Martin, al. 2014), and in southwestern british Columbia cities, E. J. Ray, J. T. Kurien, D. R. Westrop, and P. Suriya - Forsyth (1999) noted considerable localized transport wong. 2014. trading in snails: plant nurseries as distribu - of snails (although not D. rotundatus ) in garden waste, tion centers for non-native species. biological Invasions 16: soil, rock, wood, and other debris that was dumped in 1441–1451. vacant lots and undeveloped parks. Some new york Boycott, A. E. 1929. the oecology of british land Mollusca, occurrences of D. rotundatus were apparently associat - with special reference to those of ill-defined habitat. Jour - ed with outdoor, ornamental plantings or greenhouses nal of Molluscan Studies 18: 201–209. Boycott, A. E. 1934. the habitats of land Mollusca in britain. (Jacobson 1954; Karlin and naegele 1960). Vancou - Journal of ecology 22: 1–38. ver’s Queen elizabeth park, the site of a former quar - Brooks, S. T., and B. W. Brooks. 1940. Geographical distri - ry, is planted with a variety of native and exotic trees, bution of the recent Mollusca of newfoundland. annals of shrubs, and garden plants. In newfoundland, the main the Carnegie Museum 28: 53–75. nucleus for the St. John’s D. rotundatus occurrences Cameron, R. A. D., B. M. Pokryszko, and A. M. F. Martins. is almost certainly bowring park, a long-established 2001. Land snail faunas on Santa Maria (azores): local urban park planted with numerous, mainly imported, diversity in an old, isolated and disturbed island. Journal tree species, as well as many imported garden plants. of Molluscan Studies 78: 268–274. Clench, W. J., and G. Banks. 1939. Discus rotundata [sic ] this park also happens to be a short distance (3 –4 km) (Müll.) in Massachusetts. nautilus 52: 108. upstream from the city harbour, near the upper reaches Davis, D. S. 1985. Synopsis and distribution tables of land of the sheltered waterford River Valley, along the whole and freshwater Mollusca of nova Scotia. Curatorial Report length of which D. rotundatus also commonly occurs. 54. nova Scotia Museum, halifax, nova Scotia, Canada. 246 the CanaDIan FIeLD -n atuRaLISt Vol. 130

Davis, D. S. 1990. Land and freshwater snails and slugs of Holm, G. P. 2012. Some shells I would not have found had I nova Scotia. papustyla 1990: 2–5. not been walking my dog Zoe. Dredgings [pacific north - Davis, D. S. 1992. terrestrial Mollusca of nova Scotia: in the west Shell Club] 52: 6–7. footsteps of John Robert willis, 1825 –1876. pages 125–133 Jacobson, M. 1951. Discus rotundatus (Müller) in new york. in proceedings of the ninth annual Malacological Con - nautilus 65: 34–35. gress, edinburgh, 31 august–September 1986. Edited by e. Jacobson, M. 1954. Discus rotundatus (Müller) in new Jersey Gittenberger and J. Goud. unitas Malacologica, Leiden, and new york. Gastropodia 1: 9–10, pl. 6. netherlands. Jacobson, M., and W. K. Emerson. 1961. Shells of the new Drake, R. J. 1963. the history of nonmarine malacology in york City area. a handbook of the Land, Fresh water and british Columbia. pages 1–16 in Contributions to Cana - Marine Mollusks Ranging from Cape Cod to Cape May. dian Zoology 1962. bulletin 185 (biological Series 69). argonaut books, Larchmont, new york, uSa. national Museum of Canada, ottawa, ontario, Canada. Karlin, E. J., and J. A. Naegele. 1960. biology of the Mollus - Dundee, D. S. 1974. Catalog of introduced mollusks of east - ca of greenhouses in new york state. agricultural exper - ern north america (north of Mexico). Sterkiana 55: 1–37. iment Station Memoir 372. Cornell university, Ithaca, Forsyth, R. G. 1999. Distributions of nine new or little-known new york, uSa. exotic land snails in british Columbia. Canadian Field- Karstad, A. 1995. a place to walk: a naturalist’s Journal of naturalist 113: 559–568. the Lake ontario waterfront trail. natural heritage/natural Forsyth, R. G. 2004. Land Snails of british Columbia. Roy - history, toronto, ontario, Canada. al bC Museum handbook. Royal british Columbia Muse - Kerney, M. P. 1999. atlas of the Land and Freshwater Mol - um, Victoria, british Columbia, Canada. luscs of britain and Ireland. harley books, Colchester, uK. Forsyth, R. G., J. M. C. Hutchinson, and H. Reise. 2001. Kerney, M. P., and R. A. D. Cameron. 1979. a Field Guide Aegopinella nitidula (Draparnaud, 1805) (Gastropoda: to the Land Snails of britain and north-west europe. Zonitidae) in british Columbia — first confirmed north Collins, London, uK. american record. american Malacological bulletin 16: Kuźnik-Kowalska, E. 1999. Life cycle and population dy- 65–69. nam ics of Discus rotundatus (o. F. Müller, 1774) (Gas - Forsyth, R. G. 2008. First record of the european land snail tropoda: pulmonata: endodontidae). Folia Malacologica Trochulus striolatus in british Columbia, Canada (pul - 7: 5–17. monata: hygromiidae). Festivus 40: 76–78. Lee, H. G. 2009. 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