Terrestrial molluscs of the Province of Newfoundland and Labrador, Canada. Part 1: Boettgerillidae

The family Boettgerillidae, represented by the Eurasian slug Boettgerilla pallens Simroth, 1912, is first recorded for Newfoundland and Labrador, Canada—a range extension of almost exactly 5000 km within the Americas. Compiled, within an appendix, to provide a national perspective for the Newfoundland and Labrador record, are 13 previously unpublished B. pallens records from British Columbia, Canada. Incidentally recorded is the second eastern Canadian outdoor occurrence of the European slug Deroceras invadens. This paper is the first in a series that will treat all of the terrestrial molluscs of Newfoundland and Labrador.


Boettgerilla pallens
During the process of reporting the first known occurrence of B. pallens in the Americas, from the southern end of Vancouver Island, British Columbia, western Canada, Reise et al. (2000: 313) attempted to "draw worker's attention to the possibility of this species occurring in their own neighborhood in the near future, if not already", and suggested that "workers in other continents should realise that it is a potential colonist". Indeed, elsewhere in the Americas, the species has now been found at: 3 localities in the vicinity of Bogotá, Colombia in 2000 (Hausdorf 2002); 2 localities in southcentral Mexico in (Araiza-Gómez et al. 2016; and 1 locality near San Mateo, California, USA in 2013(Mc Donnell et al. 2014. In Europe, B. pallens is still being reported from new areas (e.g., the Ukraine and Bulgaria- Balashov andBaidashnikov 2012, Dedov et al. 2015), although it remains unreported from all but the very north of the Iberian and Italian peninsulas (Borredà et al. 2010, Hallgass andVannozzi 2010). As well, it has recently been found in the Canary Islands (Margry 2014).
Boettgerilla pallens is adapted for moving through earthworm burrows and other narrow soil spaces (Shikov 2007). Observations using a rhizotron found that individuals normally occur at depths of 2-20 cm, to a maximum of approximately 60 cm (Gunn 1992). The same rhizotron study found, further, that individuals were active underground during the day, when they ate mainly earthworm faeces, detritus, and soil. Several studies have reported that they will also eat other items, including carrion and roots (see review in Reise et al. 2000). Shikov (2007) observed that individual B. pallens appeared at the surface at night, where they preyed upon medium-sized snails. The species occurs in a wide range of habitats, including gardens and greenhouses (Plate 1965, De Wilde et al. 1983), but it is not known to be an agricultural or horticultural pest , Hausdorf 2002), although Moolenbeek (2002) described damage to "dozens of potatoes" [translated from Dutch] in his garden in The Netherlands.

Methods
On 14 October 2015, JEM collected 4 specimens of B. pallens in the city of St. John's, on the Island of Newfoundland, in eastern Canada; more specifically, from a sheltered, wooded slope in a mature urban environment, between Empire Avenue and Kelly's Brook ball field, just above a short unburied section of a brook of the same name (47.5731° N, 052.7112° W).
The 4 specimens were found under an approximately 25 cm diameter rock on damp bare earth, in a closedcanopy thicket of deciduous trees composed mostly of exotic maples (Acer platanoides L. and Acer pseudoplatanus L.) (Sapindaceae), with some scattered examples of a native serviceberry (Amelanchier sp.) (Rosaceae), and a dense, mid-to-late summer, understory of Wild Chervil (Anthriscus sylvestris (L.) Hoffm.) (Apiaceae) (Fig. 5).
This collection constitutes the first record of B. pallens for the Canadian province of Newfoundland and Labrador, as well as for eastern North America north of Mexico. Further, it constitutes a range extension of  In order to place the new Newfoundland record in a better national perspective, we have compiled (in the Appendix) all other known records of B. pallens for Canada. All are from British Columbia, including 4 completely new records by JMCH and HR (with others) documented herein, 4 published records in 2 papers , Neckheim 2014, and 9 records appearing in 7 unpublished technical reports (Ovaska and Sopuck 2002, 2008, Sopuck and Ovaska 2016a, 2016b, Kristiina Ovaska pers. comm. 2017. Given these 17 British Columbia records, and given their coherent, evenly spread distribution pattern, on both sides of the Strait of Georgia (Fig. 6), it is safe to conclude that the species is now well established in coastal, southwestern British Columbia. While most of the localities recorded for the Americas are situated in rather natural-looking habitat outside of gardens, 2 of the British Columbia records (southeast of Duncan, and Surrey) and the California record are from garden centres, and 1 other British Columbia record (Stanley Park) is from a large park with significant horticultural plantings. These 4 records suggest one obvious mode of dispersal within North America.

Results
The initial identification of the Newfoundland specimens was straightforward, given the unusual worm-like form of the animals while crawling (Fig. 1) (Rowson et al. 2014). Unlike in milacid slugs (which share a prominent keel running from mantle to tail; see Fig. 2), the rear of the mantle was elongated and pointed (Fig. 3), and the groove on the right side of the mantle ran only forward and backward from the top of the pneumostome (Fig.  3), instead of forming a broad U-shape, with the freewings of the "U" pointing rearward (Wiktor 1961, Wiktor 1973. The colour of the 22-24 mm long animals (measured in extended, normal crawling position; Fig. 1) was an unspeckled grey (unlike juvenile animals, which are white- Wiktor 1961, Wiktor 1973). An enlargement of the characteristic pneumostome area is shown in Figure  4. The only other species of Boettgerilla, B. compressa, is not known to occur outside of a very restricted region of the Caucasus Mountains (Sysoev and Shileyko 2009). Its brownish colour is noticeably different from that of B. pallens (Sysoev and Shileyko 2009;compare also pl. 7, fig. 29 in Simroth 1910, with tab. 3, image 50 in Simroth 1912. Twelve other species of terrestrial molluscs have been recorded at the Newfoundland B. pallens locality, all by JEM (Table 1).

Discussion
The Newfoundland occurrence of B. pallens, recorded herein, represents a significant range extension for this invasive Eurasian species, being roughly 3100 km west of the closest European (i.e., Irish) locality, and almost exactly 5000 km east of the closest British Columbia locality (Fig. 6). The closest Mexican locality is approximately 5100 km distant; the California locality is about 5600 km distant; and the closest Colombian locality is about 5200 km distant (Fig. 6). The new record of B. pallens from Newfoundland and Labrador suggests the possibility of additional occurrences in eastern North America.
Just how B. pallens reached the Island of Newfoundland remains unclear. The eastern edge of Newfoundland is the closest part of North America to Europe. For centuries (at least until the end of the Age of Sail) the harbour of St. John's, in particular, was the first North American port of call for the ships of a number of European countries. Many of these ships unloaded a great variety of European freight. Remarkably, even building stone, used primarily for fortifications, large places of worship, and merchant premises, was imported to the rocky shores of the Island. In addition, the merchant class imported many species of European vegetation, including trees, to plant in the gardens of their large houses and in local parks.
Many of the European ships, if "travelling light" to the westward (e.g., the outgoing European fishing fleets), regularly dumped ballast onto the shoreline at their destinations, in preparation for loading a paying cargo (Lindroth 1957). This ballast was often just a jumble of rocks, soil, pieces of old buildings, and whatever else was available, for free, at an earlier port-of-call. Secondarily, considerable trade in the opposite direction (i.e., eastward, often via Newfoundland) originated in northeastern North American ports, particularly those of New York and Boston.
A striking result of all of this transportation of materials is that, today, the Island of Newfoundland, especially the general St. John's area, harbours a disproportionate number of introduced species of both flora (e.g., Cooper 1981) and fauna (e.g., Morris 1983), from Europe and beyond.
How long B. pallens has been present in Newfoundland is impossible to say because, as far as we know, no malacologist had searched the location of its discovery until 2015. Given that the first large merchant's houses in the general area were built as early as the 1840s (e.g., Bannerman House), it is quite possible that at least some introduced snail and slug populations were present there as far back as the middle of the 19th century. That said, it would appear that only during the last half-century or so did B. pallens become common enough in Western Europe to qualify as a likely colonist to Newfoundland.
In order to place the recent Newfoundland discovery of B. pallens in better perspective, and to demonstrate, through a brief historical account of search effort, that the species is almost certainly truly rare there, it seems useful to give a short account of the history of terrestrial mollusc collecting in the province of Newfoundland and Labrador.
The first serious collections of terrestrial molluscs on the Island of Newfoundland were made, somewhat incidentally, by Philadelphia botanist Bayard Long, who  Reise et al. (2011), andin Forsyth (2014). This collection is significant, since it constitutes only the second outdoor record of D. invadens for eastern Canada. The first eastern Canada outdoor record of D. invadens (Forsyth 2014) was also collected from St. John's, from a location approximately 0.9 km south-southeast of the second one. Interestingly, repeated attempts by JEM to rediscover D. invadens at the first site have been unsuccessful, suggesting that the occurrence at that particular spot was ephemeral. Chichester and Getz (1969) Newfoundland, in 1924, 1926, and 1929(Fernald 1926, 1933. Long's Newfoundland mollusc collections, made mostly from limestone areas on the west coast of the Island in 1924Island in , 1925Island in , and 1929, were deposited in the Academy of Natural Sciences of Philadelphia (now the Academy of Natural Sciences of Drexel University), USA, and were published on by E. G. Vanatta (1925Vanatta ( , 1927Vanatta ( , 1930 (Brooks 1936, Brooks andBrooks 1940). On the second trip (which B.W. Brooks did not participate in), collections were also made in southern Labrador. All collections from these trips were deposited in the Carnegie Museum.
In 1964, RGN began mollusc collecting (terrestrial, freshwater, and marine) in both Newfoundland and Labrador. He was joined in this endeavour, in 1983, by JEM. Together, they have amassed significant collections of both Newfoundland and Labrador molluscs, which are now held in The Rooms Provincial Museum (Newfoundland and Labrador) (NFM). However, because of the still extremely limited road and coastal boat network available in the sparsely populated region of Labrador (1 person/11 km 2 ), mollusc collecting there remains much more of a challenge, and thus much more limited, than it is on the Island of Newfoundland. The present paper is the first in a developing series that will ultimately treat all of the terrestrial mollusc species of Newfoundland and Labrador.
In the late 1960s, Chichester and Getz (1969) collected slugs on the west coast of the Island of Newfoundland. Additional intermittent collecting has been carried out in association with the National Museums of Canada (now the Canadian Museum of Nature), the Newfoundland and Labrador Wildlife Division, and the Department of Biology, Memorial University of Newfoundland (Goudie 1997, Moss 2004, Humber 2009, Moss and Hermanutz 2010, Humber and Hermanutz 2011. As well, some minor, occasional, opportunistic collecting has been conducted by both residents (e.g., Bateman and Burzynski 2008) and "travellers in the country" (e.g., Oughton 1940). Photography has also been employed as a primary tool (Maunder and Voitk 2010).