Robert G. Forsyth

Anguispira kochi (L. Pfeiffer, 1846), the banded tigersnail, is a North American member of the family Discidae. It is typically subdivided into two subspecies: A. kochi kochi (L. Pfeiffer, 1846) and A. kochi occidentalis (E. von Martens, 1882). Genetic data from throughout the distribution of A. kochi (sensu lato) was used to produce a phylogenetic analysis and, together with morphological and distributional data, assess the taxonomic status of its subspecies. Evidence for elevating the western subspecies, A. k. occidentalis , to the rank of species level is provided and the implications this change has for the conservation status (and future conservation plans) of both species is discussed. A lectotype is designated for A. occidentalis . The status of other infraspecific taxa of both A. kochi and A. occidentalis is discussed, as well as the potential validity of subgenus Zonodiscus Pilsbry, 1948. Finally, the new classification of Discus marmorensis H.B. Baker, 1932 as Anguispira marmorensis (H.B. Baker, 1932) comb. nov. is proposed.

The correct name for a common, temperate north-western North American land snail is discussed. In a 2018 revision of the genus Vertigo O.F. Müller, 1773, “Vertigo columbiana Sterki, 1892” was used for this species by its authors, who synonymised V. andrusiana Pilsbry, 1899 with it. However, V. columbiana Sterki, 1892 is a nomen nudum and, as this name is not made available until a publication in 1900 by Pilsbry and Vanatta, the earliest available name is V. andrusiana.

Samples of leaf litter were collected from 22 woodland sites throughout Prince Edward Island, Canada. Eighty-two specimens belonging to 15 species of litter-dwelling land snails were recovered from 20 of the 22 samples. One-third of the species—Carychium exile H.C. Lea, 1842, Helicodiscus shimeki Hubricht, 1982, Strobilops labyrinthicus (Say, 1817), Perpolita binneyana (Morse, 1864), and Striatura ferrea Morse, 1864—were previously undocumented in the literature as occurring in PEI. Leaf-litter sampling, even in smaller quantities, is an effective method for finding the often-neglected terrestrial mollusc fauna, which is composed largely of minute species.

We report for the first time the terrestrial slug Prophysaon andersonii (J.G. Cooper, 1872) from Quebec, Canada. Two specimens were collected in Parc national du Bic. The identification was determined by the external morphology and partial-COI gene sequence data. The genus Prophysaon is endemic to western North America, and the new record indisputably represents an introduction. No species of Prophysaon has, until now, been noticed in North America from outside its native range.

Populations of Roman Snail, Helix pomatia, a large European land snail, are reported for the first time in Canada from disturbed habitats in two distant locations: Sarnia, Ontario and Montrose, British Columbia. As Roman Snail is an edible species subject to international commercial trade, its deliberate, but illegal, introduction into Canada and intentional or unintentional releases are possible sources of these populations.

The minute terrestrial snail Vallonia costata (O. F. Müller, 1774) is reported for the first time from the province of British Columbia, Canada. The identification was based on shell morphology and confirmed by COI gene data. This species is presumed to be introduced to the province.

A seldom-collected terrestrial snail, Guppya sterkii (Dall, 1888), is recorded for the first time from an older-growth hardwood forest in rural Ottawa, eastern Ontario. This represents a range extension of roughly 175 km north-east of the nearest previously known occurrence. Its conservation status and possible threats are briefly discussed.

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.

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.

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.