Vertigo genesii (Gredler, 1856)

Coufal, Radovan, Horsáková, Veronika, Peterka, Tomáš, Ryelandt, Julien, Skujienė, Grita & Horsák, Michal, 2024, Fig. 1 in Positive association between PTN polymorphisms and schizophrenia in Northeast Chinese Han population., Zoological Studies 63 (19), pp. 141-149 : 11-12

Vertigo genesii

Distribution

Similarly to the previous species, the distribution of V. genesii was originally known mainly from the Scandinavian mountain ranges, Finland, and Switzerland ( Kerney et al. 1983; von Proschwitz 2003; von Proschwitz et al. 2023). With the inclusion of the species into Annex II of the EU Habitats Directive (92/43/EEC), the increased survey effort led to discoveries of new sites. The majority of new records comes from Sweden, Norway, and Finland (data presented here; GBIF.org), where they extend the originally known distribution range. It is expected that the number of records will further increase in Fennoscandia, especially in northern Norway and Finland where unsurveyed suitable sites are present. Several new sites were documented also in central Ireland and the northern half of Great Britain and Ireland ( Killeen et al. 2019; Conchological Society of Great Britain & Ireland 2020). Southwards from its occurrence in the southern parts of Sweden and Finland, there is a large distribution gap extending to the Alps. Areas in this gap, i.e., the Baltic States, northeastern Poland and the Western Carpathians, the latter of ancient origin ( Hájek et al. 2011; Horsák et al. 2012), represent malacologically well explored regions. However, even extensive sampling (see Schenková et al. 2012) failed to detect presence of the species. As for the previous species, this is likely due to limited dispersal ability and/or extinction events prevailing over colonisation. The knowledge on distribution range in the Swiss and Italian Alps has also been expanded (data presented herein; Turner et al. 1998; Schenková and Horsák 2013a). Despite a high sampling effort on ecologically suitable sites in Austria, V. genesii is only known from a single site ( Duda 2015). Similarly, extensive sampling (see Lasne et al. 2021) yielded only three sites in eastern France (Jura Mountains; data presented here; Brugel 2016; Lasne 2018). The southernmost record comes from Núria near Girona, Spain ( Bech 1992). The author formerly published the record as V. cf. genesii , however, the revision of the material proved the identification to be correct ( Cadevall and Orozco 2016; Cadevall et al. 2020). The presence of calcareous fens in the area (e.g., Jiménez-Alfaro et al. 2014) suggests that the species may occur at other localities, but no extensive malacological survey of spring fens has been conducted in this area. Findings of juveniles or individuals of other Vertigo species with poorly developed aperture and dentition have led to many misidentifications and erroneous occurrence reports. Kuznecova and Skujienė (2011 2012) reported the presence of the species in Lithuania; however, in both cases juvenile individuals of other Vertigo species were misidentified for V. genesii . Pilāte (2000) reported two fossil and one subfossil individuals from Slītere National Park, Latvia. However, the description of the habitat suggests that this was likely also a misidentification. Similarly, in the report of Šatkauskienė (2001) from Lithuania, the author herself expresses doubts about the identification and mentions that more shells would be necessary to correctly identify the species. Stalažs and Dreijers (2016) state the presence of the species in all Baltic States, referring to Krausp (1940). However, prior to 1966, V. geyeri and V. genesii were not treated as separate species ( Waldén 1966), and therefore these records most likely refer to the closely related V. geyeri . The last report of occurrence comes from Pilāte et al. (2022) from Latvia who report presence of the species based on one subfossil shell, but this was most likely also a misidentification. Despite the extensive survey of ecologically suitable sites in the Baltic States, there are no reliable records so far. Similarly, V. genesii was reported also from Poland and Germany, nevertheless, these records were also based on misidentifications ( Cameron et al. 2003).

Ecology

According to the literature, V. genesii is a stenotopic species with an arctic-alpine distribution restricted to calcium-rich wetlands or wet flushes that are permanently wet but not flooded ( Kerney et al. 1983; Cameron et al. 2003; Valovirta 2003; von Proschwitz 2003; Nekola et al. 2018; von Proschwitz et al. 2023). Our results corroborate that the species distribution is clearly limited by summer and winter temperature and calcium content, i.e., it prefers base-rich sites in cold climates. Nevertheless, Schenková and Horsák (2013a) reported that V. genesii can occur in fens with calcitolerant peat mosses of Sphagno warnstorfii- Tomentypnion nitentis alliance, i.e., the habitat most frequently inhabited by the acidophilous V. lilljeborgi (see Horsák et al. 2017). Likewise, our dataset includes 32 sites where V. genesii and V. lilljeborgi occurred sympatrically. However, it is likely that these species occupied different micropatches of the sampled plot. All these sympatric occurrences come from Fennoscandia where it is more common for types of mires with varying mineral richness to co-occur and intermingle at small spatial scales ( Rydin et al. 1999). Colder climate in Fennoscandia counteracts the competitive ability of Sphagnum species in rich fens ( Hájek et al. 2022) and hence supports the co-existence of non-sphagnaceous fen mosses (so called “brown-mosses”) and Sphagnum spp. Therefore, V. genesii most likely dwelled in more alkaline patches (dominated by “brown-mosses”) while V. lilljeborgi occupied more acidic patches (dominated by Sphagnum spp. ) as the sampling was done on 16 m 2, i.e., an area that can be in some cases very heterogeneous in physicochemical conditions (e.g., Joosten et al. 2017). Our results confirm that it prefers calcium-rich sites; however, it spans a relatively wide range along the mineral richness gradient and appears to be less calciphilous than its congener V. geyeri . The need for highly alkaline sites reported by Killeen (2003) is therefore probably true in England and Scotland where this publication originated. Out of the three analysed species, it prefers the least waterlogged and vegetation-productive sites. The need for lower summer temperatures is likely one of the reasons for its very rare and scattered distribution in temperate Europe. This is also consistent with earlier literature describing the species as boreo-alpine ( Kerney et al. 1983) or arctic-alpine ( Cameron et al. 2003), as low temperatures are typical for high altitudes. Even in northern Europe, the species’ optimum is at higher altitudes, although it also occurs in the subalpine region ( von Proschwitz 2003; von Proschwitz et al. 2023). An exception, however, is the occurrence of V. genesii at considerably lower altitudes between 75 and 525 m a.s.l. in the United Kingdom ( Killeen 2003; Killeen et al. 2019). Therefore, global warming associated with ongoing climatic change (Essl et al. 2012) poses a serious threat for this species, together with human-induced eutrophication as the species prefers nutrient-poor sites.