Inferring the sources of postglacial range expansion in two large European land snails

Diversity of Land Snail Tribe Helicini (Gastropoda: Stylommatophora: Helicidae): Where Do We Stand after 20 Years of Sequencing Mitochondrial Markers?

Sequences of mitochondrial genes revolutionized the understanding of animal diversity and continue to be an important tool in biodiversity research. In the tribe Helicini, a prominent group of the western Palaearctic land snail fauna, mitochondrial data accumulating since the 2000s helped to newly delimit genera, inform species-level taxonomy and reconstruct past range dynamics. We combined the published data with own unpublished sequences and provide a detailed overview of what they revealed about the diversity of the group. The delimitation of Helix is revised by placing Helix godetiana back in the genus and new synonymies are suggested within the genera Codringtonia and Helix. The spatial distribution of intraspecific mitochondrial lineages of several species is shown for the first time. Comparisons between species reveal considerable variation in distribution patterns of intraspecific lineages, from broad postglacial distributions to regions with a fine-scale pattern of allopatric lineage replacement. To provide a baseline for further research and information for anyone re-using the data, we thoroughly discuss the gaps in the current dataset, focusing on both taxonomic and geographic coverage. Thanks to the wealth of data already amassed and the relative ease with which they can be obtained, mitochondrial sequences remain an important source of information on intraspecific diversity over large areas and taxa.

The introduction of the European Caucasotachea vindobonensis (Gastropoda: Helicidae) in North America, its origin and its potential range

We report the introduction of the central and eastern European helicid land snail Caucasotachea vindobonensis in North America. It was first recorded from Rensselaer County in the state of New York in 2015 by a community scientist. From 2016 to 2020, 14 additional occurrences in Rensselaer County, neighbouring Albany County and an imprecisely localized site in the Adirondack Mountains were recorded by community scientists. In 2020, the species was newly recorded at two sites in Schoharie County, NY, and at three sites in Québec, one of them approximately 700 km to the north of the initial record. Partial mitochondrial cox1 sequences from Rensselaer differ from an eastern Ukrainian haplotype only in a single substitution. Therefore, a Ukrainian origin for this introduction is likely, although not certain: the Rensselaer haplotype also differs in only two substitutions from a more widespread haplotype known from Ukraine, Hungary, Slovakia, Czechia, Serbia, and Bulgaria. An environmental niche model of the species based on occurrence data from central and eastern Europe indicated that a large region from the northern east coast to the midwestern United States is suitable for C. vindobonensis. The Canadian occurrences may indicate that the North American lineage is able to survive colder winters than predicted by the environmental niche model. Caucasotachea vindobonensis is not listed as a pest in Europe and it is unlikely to become an agricultural pest in North America as it prefers rotting plant material over living parts of plants, but its impact on native organisms can hardly be predicted.

Geographic isolation and human-assisted dispersal in land snails: a Mediterranean story of Helix borealis and its relatives (Gastropoda: Stylommatophora: Helicidae)

The Mediterranean basin is a major centre for land-snail diversity, with many localized endemics, but there are also species widely spread by humans. Both endemics and introductions can be found in the snail genus Helix, which comprises many large-bodied species used for human consumption in the past and present. The Mediterranean clade of Helix is currently distributed throughout this region, but the phylogenetic and biogeographic relationships among its forms from different parts of the basin remain enigmatic. The reasons include insufficient sampling, taxa with unclear taxonomy and a significant impact of human-assisted transport obscuring the natural distribution of phylogenetic lineages. We provide evidence that European and Anatolian populations of H. cincta and its relatives are not native to those regions, but originate from the northern Levant. These results have implications for taxonomy of the genus, but also for the understanding of its evolutionary history. We posit that the Mediterranean clade consists of four geographically separated groups, which diversified in Northern Africa, the Apennine Peninsula and Corsica, the Aegean and Greece, and the northern Levant. This geographic pattern has been subsequently blurred by multiple instances of human-assisted dispersal. However, revealing the founding populations with certainty requires thorough sampling in currently inaccessible countries.

Malacological news from the Czech and Slovak Republics in 2015–2019

Since the last comprehensive overview of the Czech and Slovak mollusc fauna, released in 2013, several records of species new for the countries or particular regions have appeared. In this paper, we summarize all such records and news collected in 2015–2019, including those affecting nomenclature and the national Check-lists made in 2013 and 2014. The rules for the selection of the records are: (i) the first record in Bohemia, Moravia or Slovakia, (ii) regionally important new records, (iii) records of species listed in NATURA 2000 and the national Red-lists as either critically endangered or endangered species, and (iv) currently spreading non-native species. New records are briefly commented and summarized for each species separately. Location data are published with all details in a supplementary table and are freely accessible.