Ecology and Current Distribution of Three Habitat-Specialized Land Snail Species of the Genus Vertigo (Gastropoda: Eupulmonata) in Europe

© 2024 Academia Sinica, Taiwan Open Access Ecology and Current Distribution of Three Habitat-Specialized Land Snail Species of the Genus Vertigo (Gastropoda: Eupulmonata) in Europe Radovan Coufal1,* , Veronika Horsáková1, Tomáš Peterka1, Julien Ryelandt2, Grita Skujienė3, and Michal Horsák1 1Department of Botany and Zoology, Faculty of Science, Masaryk University, Brno, Czechia. *Correspondence: E-mail: radovan. [email protected] (Coufal) E-mail: [email protected] (Horsáková); [email protected] (Peterka); [email protected] (Horsák) 2Conservatoire Botanique National de Franche-Comté – Observatoire Régional des Invertébrés, Besançon, France. E-mail: [email protected] (Ryelandt) 3Department of Zoology, Institute of Biosciences, Life Sciences Center, Vilnius University, Saulėtekio av. 7, LT-10223 Vilnius, Lithuania. E-mail: [email protected] (Skujienė) Received 5 April 2023 / Accepted 14 March 2024 / Published 16 July 2024 Communicated by Benny K.K. Chan Our understanding of species distribution and ecology is critical to properly assess their conservation status. Vertigo lilljeborgi, V. genesii, and V. geyeri have the centre of their current distribution in northern Europe, where their occurrence is relatively frequent. However, to the south their occurrence is fragmented and restricted to sites of late glacial/early Holocene origin. In the last ~30 years, there has been an increase in records, connected with the listing of the latter two species in Annex II of the EU Habitats Directive (94/43/EEC). However, there is no comprehensive publication documenting their pan-European distribution. Therefore, we assembled all available data from online databases, books, and scientific literature and combined them with our unpublished records to create distribution maps. The results show a more frequent occurrence in temperate Europe than previously known, especially for V. geyeri. Analyses performed on data from 327 ecologically potentially suitable sites, covering the entire distribution range of the species, have improved our knowledge of their ecology. Vertigo lilljeborgi and especially V. genesii are restricted to areas with lower summer and winter temperatures, and therefore, their further decline is expected in the face of rising temperatures due to climate change. The preference of V. geyeri for higher temperatures, in comparison to the latter two species, may explain its relatively frequent distribution in temperate Europe. Vertigo lilljeborgi favors base-poor sites, while V. genesii and V. geyeri prefer calciumrich sites, with the latter being the most calcicolous. Their need for a stable water regime and lowproductive sites, known from previous studies, was not conspicuous in our results, probably due to the selection of sites well within the species range. Despite the increase in record frequency, these species are still endangered, especially in temperate Europe. Their sites should therefore be strictly protected as sites of high biological diversity and conservation value. Because of their relict nature, these land snails should be considered umbrella species and indicators of well-preserved groundwater-dependent ecosystems in temperate Europe. Key words: Glacial relicts, EU Habitats Directive, IUCN Red List species, Climate change, Vertigo lilljeborgi, Vertigo genesii, Vertigo geyeri Citation: Coufal R, Horsáková V, Peterka T, Ryelandt J, Skujienė G, Horsák M. 2024. Ecology and current distribution of three habitat-specialized land snail species of the genus Vertigo (Gastropoda: Eupulmonata) in Europe. Zool Stud 63:19. doi:10.6620/ZS.2024.63-19. Zoological Studies 63:19 (2024) doi:10.6620/ZS.2024.63-19 1 © 2024 Academia Sinica, Taiwan BACKGROUND The land snails of the genus Vertigo O. F. Müller, 1774 are currently represented by ~100 species and subspecies (Nekola et al. 2018). They have worldwide distribution (Nekola and Coles 2016), with the majority of known species occurring in the Holarctic region and occupying a variety of habitats from forests to open wetlands (Horsák et al. 2024). Nowadays, the genus reaches its highest species richness in North America (Nekola and Coles 2010), whereas in Europe, only 15 extant species are known (von Proschwitz 2003). The affinity of several genus representatives to cold and damp habitats is most apparent in species considered glacial relics, e.g., Vertigo lilljeborgi, V. genesii, and V. geyeri, due to their wide distribution in periglacial Europe during the Late Glacial and Early Holocene (e.g., Jaeckel 1962; Ložek 1964 1992). They are currently restricted to wetland habitats, predominantly to minerotrophic fens (Cameron et al. 2003; Schenková and Horsák 2013a). With the climate change at the end of the last glacial period, their main distribution area shifted to the boreal and arctic zones. In the temperate zone, however, they settled in the middle and more often in the higher elevations of the main mountain systems. As these occurrences are rare and fragmentary, the two former species have been listed in Annex II of the EU Habitats Directive (92/43/EEC). The presence of V. geyeri has been shown to indicate that particular sites are hundreds to thousands of years old, (Hájek et al. 2011; Horsák et al. 2012; Peterka et al. 2022), making it a valuable umbrella species. For the other two species, relict status is also expected (Schenková and Horsák 2013a; Horsák et al. 2017). All three species are mainly threatened by human impacts, namely by direct destruction of habitats, drainage, and nutrient input followed by succession towards more productive habitats that cannot support their persistence (e.g., Cameron et al. 2003; Vavrová et al. 2009; Schenková and Horsák 2013a; Horsák et al. 2017). They are also very likely to be threatened by climate change due its impact on site hydrology (Essl et al. 2012; Gong et al. 2012; Coufal et al. 2023). Until recently, the knowledge on distribution of these species in temperate Europe was substantially underestimated, as malacologists have mostly focused on different types of habitats. For example, V. geyeri was found in Czechia for the first time in 1991 (Ložek 1993). However, this single known population became extinct due to inadequate conservation management of the site. After that, the species was considered extinct in the country until another population was discovered in 2011 (Myšák et al. 2012), followed by two dozen additional newly discovered sites (e.g., Schenková and Horsák 2013b; Coufal 2019). Not only in Czechia, but also in other European countries, the number of records of these glacial relics continues to increase due to extensive surveys and growing knowledge of their habitats (e.g., Schenková et al. 2012; Skujienė et al. 2019; Gabriel 2020). During the last three decades, many new sites of these species were discovered throughout Europe. However, there is no outright source of species distribution since most of the results are scattered across databases, local literature, and survey reports, making it difficult to access. On top of that, many of these findings have not been published. Furthermore, ecological demands were analyzed only for V. lilljeborgi (Horsák et al. 2017) and V. geyeri (Horsák and Hájek 2005; Schenková et al. 2012), and were based on data from a limited portion of their distribution range. These studies show that the species differ in their tolerance to water pH and air temperature. While V. lilljeborgi is limited to sites of neutral to slightly acidic pH (Pokryszko 1990), V. genesii inhabits mainly highly alkaline treeless fens (Killeen 2003). Vertigo geyeri is reported to have a relatively high tolerance to mineral richness variation, avoiding only extremely calcareous and very acidic mires (Cameron et al. 2003; Schenková et al. 2012). Vertigo lilljeborgi and V. genesii are predominantly restricted to areas of cold climate (Cameron et al. 2003; Horsák et al. 2017), while V. geyeri is also frequently found in warmer areas (Schenková et al. 2012). The current increase in distributional data about these three wetland specialists calls for: 1) assembling as many unpublished records on their occurrence as possible, 2) creating maps of their currently known distribution in Europe based on unpublished personal records in combination with literature and online databases, and 3) analyzing the species ecological requirements using data spanning across their entire European distribution range. MATERIALS AND METHODS Study area The studied area in this article is limited to Europe. Quantitative sampling (personal records) Sites selected for sampling covered only minerotrophic fens, as these are the main habitats supporting persistence of the species. To sample molluscs at each surveyed site, a 12 L volume sample of an upper herbaceous layer consisting of vascular plants and bryophytes was processed using a wet sieving page 2 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan technique (for details see Horsák 2003). Dried mollusc samples were sorted and identified to the species level. Nomenclature follows Nekola et al. (2018). Dataset for ecological analyses and environmental predictors From all quantitatively sampled fens, we selected only sites with the occurrence of at least one of the target species. The reason for this was to conduct the analysis based on data that include sites where the given species is absent, but at least one of the other two species is present. Therefore, all of the included sites are well preserved and of historical continuity, as they harbor at least one of these relict species. This setting ensured suitable ecological conditions and eliminated the possibility of disrupted historical continuity of the site. In total, the dataset included 103 populations of V. lilljeborgi, 59 of V. genesii and 222 of V. geyeri (some of them harboring two or all three of these species). The selection of environmental predictors was based on publications investigating their ecological requirements (e.g., Kerney et al. 1983; Cameron et al. 2003; Horsák et al. 2017). To analyze climatic tolerance, selected air temperature variables (BIO5 = maximum temperature of warmest month, hereafter summer temperature, and BIO6 = minimum temperature of coldest month, hereafter winter temperature) were extracted using the WorldClim v1.4 database (Hijmans et al. 2005) and the ArcGIS 10.3 software. In previous studies, altitude was often found to be an important predictor in determining the occurrence of the target species (e.g., Kerney et al. 1983; von Proschwitz 2003), especially in temperate Europe. However, the availability of direct climate data allowed us to replace altitude with ecologically more relevant climatic variables, namely air temperature. As calcium content is an important driver of land snail distribution, water conductivity was measured during the fieldwork in waterlogged areas using the digital portable device HACH HQ40d. Water conductivity was found to be an excellent proxy for dissolved calcium concentration, as it reflects mainly the concentration of Ca2+ and Mg2+ in fens (Horsák 2006). Because all study species strongly respond to water regime and vegetation productivity, we used Ellenbergtype indicator values (EIVs) as a proxy for site moisture and macro-nutrient availability of the studied sites. For moisture, EIVs for European species of vascular plants and bryophytes occurring in mires were used (Hájek et al. 2020). For nutrients, original Ellenberg indicator values available for vascular plants were used (Ellenberg and Leuschner 2010). Statistical analyses The Kruskal-Wallis Rank Sum Test and the Dunn post-hoc test were used to test differences among species in variation of environmental parameters (package “FSA”, Ogle et al. 2023). Prior to subsequent analyses, variables were square rootor log-transformed to normalize their distribution. To determine the order of environmental variable importance for each species, a classification tree (CART; Breiman et al. 1984) was computed using the “rpart” package (Therneau et al. 2022). This method is used to reveal non-linear relationships between predictors. We used a complexity parameter (cp) based on the tree complexity and sum of errors to determine the optimal size of the tree (number of splits). The sites with measured environmental variables for all three species were combined and sorted into three categories for each species individually: absent, species was not recorded; weak, number of recorded live individuals per 12 L volume sample varied between 1–5 (V. lilljeborgi), 1–15 (V. genesii), and 1–10 (V. geyeri); strong, number of recorded live individuals varied between 6–32 (V. lilljeborgi), 16–157 (V. genesii), and 11–114 (V. geyeri). These numbers were chosen arbitrarily, but the rationale was to consider differences in population densities among species and to evenly divide the sites with species presence into two equal parts. Generalized Linear Models (GLMs) were used to test the relationship between environmental predictors and presence/absence of the species on the site (binomial data). Generalized Additive Models (GAMs) were used to project relationships between species abundance and environmental predictors in cases of non-linear responses. The amount of explained variation, i.e., deviance explained, for GAMs was computed using the “mgcv” package (Wood 2022). R software version 4.2.2 (R Core Team 2022) was used to compute all analyses. All graphical outputs, except the classification tree, were generated using the package “ggplot2” (Wickham 2016). Species distribution maps were created using the ArcGIS 10.3 software. RESULTS Distribution Based on all assembled records, Vertigo lilljeborgi occurs frequently in Fennoscandia and northern parts of the United Kingdom. The species was originally known from seven countries prior to 2000, while the current number has increased to 16 (Table 1). The new records are consistent with the distribution known from the older literature and show a previously unknown page 3 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan scattered occurrence in the Baltic States and Belarus, followed by a distribution gap spanning over Baltic Russia and Poland (Fig. 1). A relatively frequent but regionally restricted distribution was discovered in Central Europe in Czechia and adjacent parts of Germany, and a rare distribution was found in the Alps, Massif Central (France), and the Pyrenees (France and Spain). The main distribution area of V. genesii spans over the central part of Scandinavia, with scattered distribution in Finland and disjunct populations in the central Alps. The new records are consistent with the a priori known distribution range and show a scattered distribution in southern Scandinavia, the United Kingdom and Finland, and extend the previously known distribution in the Alps, with two isolated records from Austria and Spain (Fig. 2). The species was known from six countries prior to 2000, while now the number has increased to ten (Table 1). The new records of V. geyeri confirm the previously reported main area of distribution in Scandinavia and the discontinuous populations in Finland and the Alps. Nevertheless, a plethora of sites were discovered in the Baltic States, Belarus, Poland, Slovakia, Czechia and the Alps, with the southeasternmost records from the Romanian Carpathians and the southernmost from the Apennine Mountains (Fig. 3). The species was formerly known from ten countries, while to date the extant populations have been documented from 20 countries (Table 1). Most of the records of V. genesii and V. geyeri come from around and after 2000, while the records of V. lilljeborgi are more evenly distributed over time (Fig. 4). Unpublished records of all species are summarized in table S1. Ecological requirements Based on available data, we found that Vertigo lilljeborgi occupies a relatively broad temperature range but has a narrow alkalinity niche that restricts it to mineral-poorer sites (Fig. 5). Accordingly, the classification tree showed that it prefers sites with low alkalinity, lower summer temperatures, high waterlogging, and avoids extremely oligotrophic conditions, i.e., sites with water conductivity below 224 µS/cm, July temperatures below 20°C, moisture above 8 EIV, and nutrient availability above 2.1 EIV (Fig. 6a; Table 2). In concordance, the Generalized Linear Models (GLMs; Table 3; Fig. S1) showed that V. lilljeborgi occurs mainly at sites with lower summer and winter temperatures, low alkalinity and high moisture. The species showed a unimodal response to summer temperature, as its abundance peaked around 17°C (Dev. Explained: 0.16; p < 0.001; Fig. 7). Vertigo genesii avoids sites of high summer temperature, and prefers rather alkaline and low productive sites (Fig. 5). Similarly, the classification tree analysis showed its affinity for colder climate and higher water conductivity, i.e., summer temperatures below 16°C and water conductivity above 137 µS/ cm (Fig. 6b; Table 2). Likewise, GLMs supported its preference for lower summer and winter temperatures (Table 3; Fig. S1). Vertigo geyeri showed an affinity for sites with warmer temperatures (summer and winter) and a broad niche with respect to water conductivity and nutrient availability, with these predictors having the highest median values of all species (Fig. 5). The classification tree showed an affinity for warmer sites with higher alkalinity and lower nutrient availability. Specifically, they prefer sites with summer temperatures above 18.5°C and winter temperatures above 12°C, with water conductivity above 359 µS/cm, and nutrient Table 1. Species distribution in European countries. Symbols: † - extinct; ? - dubious records; * - rare (1–9 sites); ** - scattered (10–29 sites); (**) - frequent only locally or regionally (10–29 sites); (***) - frequent only locally or regionally (30 and more sites); *** - widespread (30 and more sites); grey, occurrence known prior to 2003 (Kerney et al. 1983; Cameron et al. 2003). Frequency is based on actual records, not literature estimates Country Species V. lilljeborgi V. genesii V. geyeri Norway *** ** ** Finland *** ** ** Sweden *** (***) *** Estonia * ? ** Latvia ** ? * Lithuania * ? (**) Denmark * - *** Belarus * - ** Ireland *** ** *** Great Britain *** *** *** Germany * - ** Poland - - *** Ukraine - - † France ** * (***) Czechia ** - (***) Slovakia - - (***) Switzerland * *** (***) Austria * * ** Romania - - * Slovenia - - - Italy - * * Spain * * - page 4 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan Fig. 1. Vertigo lilljeborgi distribution map. page 5 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan Fig. 2. Vertigo genesii distribution map. page 6 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan Fig. 3. Vertigo geyeri distribution map. page 7 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan availability below 2.7 EIV (Fig. 6c; Table 2). Similarly, GLMs showed preference for higher summer and winter temperatures, and a tolerance to a large variation in water conductivity. Nevertheless, GLMs showed a rather wide tolerance to nutrient availability (Table 3; Fig. S1). The abundance of the species increased with increasing summer temperature up to 21°C and then reached a plateau (Dev. Explained: 0.26; p < 0.001; GAMs; Fig. 7) and increased in response to increasing water conductivity, peaking at 550 µS/cm and then decreasing (Dev. Explained: 0.14; p < 0.001). DISCUSSION Vertigo lilljeborgi Distribution The main distribution area of Vertigo lilljeborgi spans over the boreal and arctic zones (see von Proschwitz 1993 2003; von Proschwitz et al. 2023). It has the most continuous occurrence in Fennoscandia when compared to the other two species and is also frequent in the northwestern parts of Great Britain and Ireland. Regarding these regions, the new records confirm the distribution documented by Kerney et al. (1983), with the exception of the southern half of Great Britain, where new sites have been discovered. The new personal records presented here show relatively Fig. 4. Histograms showing frequency of all assembled records over time. Fig. 5. Variation of analysed environmental predictors using box and whisker plots. Letters above boxplots indicate homogeneous/heterogeneous groups (Kruskal-Wallis test followed by Dunn post hoc texts). The central line of each boxplot refers to the median value, the box delineates the first and third quartiles, whiskers refer to the non-outlier values and asterisks indicate outliers. page 8 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan Fig. 6. Classification tree for the occurrence of a) V. lilljeborgi, b) V. genesii and c) V. geyeri at 327 sites. Numbers at each node indicate that the species was: absent/low population density/high population density, respectively. See Materials and Methods for details. The major splitter predictor and its split values are in bold whereas surrogates (i.e., predictors that distribute at least 90% of the cases to the same group as the primary splitter) are below the major splitter. Numbers in black circles indicate the number of splits. Photographs: Radovan Coufal (live individuals), Michal Horsák (shells). page 9 of 17 Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan Mitteleuropas 2 (1 Ergänzung). Quelle and Meyer, Leipzig, DE. Jamrichová E, Hájková P, Horsák M, Rybníčková E, Lacina A, Hájek M. 2014. Landscape history, calcareous fen development and historical events in the Slovak Eastern Carpathians. Veget Hist Archaeobot 23:497–513. doi:10.1007/s00334-013-0416-0. Jensen K, Schrautzer J. 1999. Consequences of abandonment for a regional fen flora and mechanisms of successional change. Appl Veg Sci 2:79–88. doi:10.2307/1478884. Jiménez‐Alfaro B, Hájek M, Ejrnaes R, Rodwell J, Pawlikowski P, Weeda EJ, Laitinen J, Moen A, Bergamini A, Aunina L, Sekulová L, Tehvanainen T, Gillet F, Jandt U, Dítě D, Hájková P, Corriol G, Kondelin H, Díaz TE. 2014. Biogeographic patterns of base‐rich fen vegetation across Europe. Appl Veg Sci 17:367– 380. doi:10.1111/avsc.12065. Joosten H, Tanneberger F, Moen A. (Eds.) 2017. Mires and Peatlands of Europe. Schweizerbart Science Publishers, Stuttgart, DE. Kerney MP, Cameron RAD, Jungbluth JH. 1983. Die Landschnecken Nord-und Mitteleuropas: Ein Bestimmungsbuch für Biologen und Naturfreunde. Parey, Hamburg, DE. Killeen IJ, Willing M, Moorkens E. 2019. Site Condition Monitoring of Vertigo geyeri and Vertigo genesii 2017. Scottish Natural Heritage Research Report No. 1161. Killeen IJ. 2003. A review of EUHSD Vertigo species in England and Scotland (Gastropoda, Pulmonata: Vertiginidae). In: Speight MCD, Moorkens E, Falkner G (eds) Proceedings of the workshop on conservation biology of European Vertigo species (Dublin, Ireland, April 2002). Heldia 5 (Sonderheft 7), Munich, Germany, pp. 73–84. Krausp C. 1940. Beitrag zur Molluskenfauna Lettlands. Tartu Ülikooli juures oleva Loodusuurijate Seltsi aruanded, 45:217–270, Tartu. Książkiewicz Z, Biereznoj-Bazille U, Krajewski L, Goldyn B. 2015. New records of Vertigo geyeri Lindholm, 1925, V. moulinsiana (Dupuy, 1849) and V. angustior Jeffreys, 1830 (Gastropoda: Pulmonata: Vertiginidae) in Poland. Folia Malacol 23:121–136. doi:10.12657/folmal.023.006. Kuczyńska A, Moorkens E. 2010. Micro-hydrological and micrometeorological controls on survival and population growth of the whorl snail Vertigo geyeri Lindholm, 1925 in groundwater fed wetlands. Biol Conserv 143:1868–1875. doi:10.1016/ j.biocon.2010.04.033. Kurylyk BL, Bourque CA, MacQuarrie KT. 2013. Potential surface temperature and shallow groundwater temperature response to climate change: an example from a small forested catchment in east-central New Brunswick (Canada). Hydrol Earth Syst Sci 17:2701–2716. doi:10.5194/hess-17-2701-2013. Kuznecova V, Skujienė G. 2011. Biodiversity of terrestrial molluscs in urbophytocoenoses of Vilnius, capital of Lithuania. IOBC/wprs Bulletin 64:41–51. Kuznecova V, Skujienė G. 2012. Rare terrestrial molluscs’ species of Kaunas and Kaišiadoriai districts’ reserves. Acta Biol Univ Daugavpiliensis 12:69–83. Lasne O, Ryelandt J, Horsák M, Horsáková V. 2021. Étude de l’habitat et des exigences écologiques du Vertigo geyeri Lindholm, 1925 dans le Massif jurassien. In: Léonard L (ed): Colloque national de malacologie continentale. Nantes 6:21–33. doi:10.5852/ naturae2021a2. Lasne O. 2018. Étude de l’habitat et des exigences écologiques du Vertigo geyeri Lindholm, 1925 dans le massif jurassien. Master’s thesis, Conservatoire botanique national de Franche-Comté – Observatoire régional des Invertébrés, Besançon. Lecaplain B. 2013. Un nouveau mollusque de la Directive HabitatsFaune-Flore pour la France: découverte du Vertigo septentrional Vertigo geyeri Lindholm, 1925 (Gastropoda, Vertiginidae) en Franche-Comté et en Haute-Savoie. MalaCo 9:453–456. Ložek V. 1964. Quartärmollusken der Tschechoslowakei. ČSAV, Prague, CZ. Ložek V. 1992. [Molluscs (Mollusca)]. [Red data book of endangered and rare plant and animal species of the ČSFR. 3. Invertebrates]. Príroda, Bratislava, SK. Ložek V. 1993. Vertigo geyeri in Böhmen. Dtsch Malakozool Ges 50/51:53–54. Menberg K, Blum P, Kurylyk BL, Bayer P. 2014. Observed groundwater temperature response to recent climate change. Hydrol Earth Syst Sci 18:4453–4466. doi:10.5194/hess-18-44532014. Myšák J, Horsák M, Hlaváč J. 2012. Jedna špatná a jedna dobrá zpráva o vrkoči Geyerově – z červené knihy našich měkkýšů. Živa 60:73–74. Natural Resources Wales. 2020. Welsh Invertebrate Database (WID). Occurrence dataset. Accessed via GBIF.org on 13 Dec. 2022. doi:10.15468/bv8fcj. Nekola JC, Chiba S, Coles BF, Drost CA, von Proschwitz T, Horsák M. 2018. A phylogenetic overview of the genus Vertigo O. F. Müller, 1773 (Gastropoda: Pulmonata: Pupillidae: Vertigininae). Malacologia 62:21–161. doi:10.4002/040.062.0104. Nekola JC, Coles BF. 2010. Pupillid land snails of eastern North America. Am Malacol Bull 28:29–57. doi:10.4003/006.028.0221. Nekola JC, Coles BF. 2016. Supraspecific taxonomy in the Vertiginidae (Gastropoda: Stylommatophora). J Molluscan Stud 82:208–212. doi:10.1093/mollus/eyv034. Ogle DH, Doll JC, Wheeler AP, Dinno A. 2023. FSA: Simple Fisheries Stock Assessment Methods. R package version 0.9.4. Available at: https://CRAN.R-project.org/package=FSA. Peterka T, Tichý L, Horsáková V, Hájková P, Coufal R, Petr L, Dítě D, Hradílek Z, Hrivnák R, Jiroušek M, Plášek V, Plesková Z, Singh P, Šmerdová E, Štechová T, Mikulášková E, Horsák M, Hájek M. 2022. The long history of rich fens supports persistence of plant and snail habitat specialists. Biodiv Conserv 31:39–57. doi:10.1007/s10531-021-02318-0. Pilāte D. 2000. Spermodea lamellata (Jeffreys, 1830) un Vertigo genesii (Gredler, 1856) (Gastropoda: Pulmonata) Latvijā. [Spermodea lamellata (Jeffreys, 1830) and Vertigo genesii (Gredler, 1856) (Gastropoda: Pulmonata) in Latvia]. Raksti par dabu 1:3–5. Pilāte D, Spuņģis V, Skuja A, Ozoliņš D. 2022. Investigation of occurrence of specially protected whorl snails Vertigo spp. in the habitats of EU importance. 80th International Scientific Conference of the University of Latvia. Innovative and applied research in Biology, Proceedings 4:23–25 doi:10.22364/ iarb.2022.03. Pokryszko BM. 2003. Vertigo of continental Europe—autecology, threats and conservation status. In: Speight MCD, Moorkens E, Falkner G (eds) Proceedings of the workshop on conservation biology of European Vertigo species (Dublin, Ireland, April 2002). Heldia 5 (Sonderheft 7), Munich, Germany, pp. 13–25. Pokryszko BM, Ruta R, Książkiewicz-Parulska Z. 2016. The first record of Vertigo geyeri Lindholm, 1925 (Gastropoda: Pulmonata: Vertiginidae) in north-western Poland. Folia Malacol 24:63–68. doi:10.12657/folmal.024.009. Pokryszko BM. 1990. The Vertinigidae of Poland (Gastropoda: Pulmonata: Pupilloidea) - a systematic monograph. Ann Zool 8(43). R Core Team. 2022. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available at: https://www.R-project.org/. Roy C, Vanderpert H. 2016. Découverte de Vertigo geyeri Lindholm, 1925 en Provence-Alpes-Côte d’Azur. Folia Conchyliologica 35:1–5. page 16 of 17Zoological Studies 63:19 (2024) © 2024 Academia Sinica, Taiwan Rudzīte M, Dreijers E, Ozoliņa-Moll L, Parele E, Pilāte D, Rudzītis M, Stalažs A. 2010. Latvijas gliemji Sugu noteicejs [A Guide to the Molluscs of Latvia]. Akadēmiskais apgāds, Rīga, LV. Rydin H, Sjörs H, Löfroth M. 1999. Mires. Acta Phytogeogr Suec 84:91–112. Šatkauskienė I. 2001. Naujos šliužų rūšies Lietuvoje Boettgerilla pallens ir retųjų Lietuvos sausumos moliuskų rūšių apžvalga. [A review of rare Lithuanian terrestrial malacofauna species and the Boettgerilla pallens species new to Lithuania]. Ekologija 2:56–60. Schenková V, Horsák M, Plesková Z, Pawlikowski P. 2012. Habitat preferences and conservation of Vertigo geyeri (Gastropoda: Pulmonata) in Slovakia and Poland. J Molluscan Stud 78:105– 111. doi:10.1093/mollus/eyr046. Schenková V, Horsák M. 2013a. Refugial Populations of Vertigo lilljeborgi and V. genesii (Vertiginidae): New Isolated Occurrences in Central Europe, Ecology and Distribution. Am Malacol Bull 31:323–329. doi:10.4003/006.031.0211. Schenková V, Horsák M. 2013b. Nové nálezy vrkoče Geyerova potvrzují jeho ohroženost – z červené knihy našich měkkýšů. Živa 5:238–239. Skujienė G, Kuznecova V, Jukonis B, Juzėnas S. 2020. New records of rare Vertiginidae (Mollusca: Gastropoda) in Lithuania. Bull Lithuanian Entomol Soc 4:132–140. Skujienė G, Kuznecova V, Juzėnas S. 2019. New records of Vertigo geyeri (Gastropoda: Vertiginidae) in Lithuania. Bull Lithuanian Entomol Soc 3:132–139. Skujienė G, Kuznecova V, Juzėnas S. 2021. Additional data on rare Vertiginidae (Mollusca: Gastropoda) in Lithuania. Bull Lithuanian Entomol Soc 5:118–125. Stalažs A, Dreijers E. 2016. Annotated checklist of the molluscs of the Baltic countries. Raksti par Dabu 2:9–20. Therneau T, Atkinson B, Ripley B. 2022. rpart: Recursive partitioning for classification, regression and survival trees. An implementation of most of the functionality of the 1984 book by Breiman, Friedman, Olshen and Stone. R package version 4. 1. 19. Turner H, Kuiper JGJ, Thew N, Bernasconi R, Ruetschi J, Wuthrich M, Gosteli M. 1998. Atlas of the Mollusca of Switzerland and Liechtenstein. Centre Suisse de cartographie de la faune 1998 (CSCF/SZKF), Neuchâtel, Switzerland. Valovirta I. 2003. The habitat and status of Vertigo angustior, V. genesii and V. geyeri in Finland and nearby Russian Karelia (Gastropoda, Pulmonata: Vertiginidae). In: Speight MCD, Moorkens E, Falkner G (eds) Proceedings of the workshop on conservation biology of European Vertigo species (Dublin, Ireland, April 2002). Heldia 5 (Sonderheft 7), Munich, Germany, pp. 85–94. van Regteren Altena CO. 1934. Note sur une récolte de mollusques aux environs de Font-Romeu. Journal de Conchyliologie 78:262–269. Vavrová LU, Horsák M, Šteffek J, Čejka T. 2009. Ecology, distribution and conservation of Vertigo species or European importance in Slovakia. J Conchol 40:61. von Proschwitz T. 1993. Habitat selection and distribution of ten vertiginid species in the province of Dalsland (SW. Sweden) (Gastropoda, Pulmonata: Vertiginidae). Malakologische Abhandlungen Staatlisches Museum für Tierkunde Dresden 16:177–212. von Proschwitz T. 2003. A review of the distribution, habitat selection and conservation status of the species of the genus Vertigo in Scandinavia (Denmark, Norway and Sweden) (Gastropoda, Pulmonata: Vertiginidae). In: Speight MCD, Moorkens E, Falkner G (eds) Proceedings of the workshop on conservation biology of European Vertigo species (Dublin, Ireland, April 2002). Heldia 5 (Sonderheft 7), Munich, Germany, pp. 27–50. von Proschwitz T. 2004. On the distribution and ecology of Vertigo substriata (Jeffreys), Vertigo modesta arctica (Wallenberg), Vertigo lilljeborgi (Westerlund) and Vertigo alpestris Alder in France and on the Iberian Peninsula. J Conchol 38:411–420. von Proschwitz T, Roth J, Lundin K, Back R. 2023. Nationalnyckeln till Sveriges flora och fauna. Blötdjur: Snyltsnäckor-skivsnäckor. Mollusca: Pyramidellidae-Planorbidae. SLU Artdatabanken, Uppsala, Sweden. Vrignaud S. 2012. Inventaire des mollusques de la réserve naturelle nationale de Chastreix-Sancy (Puy-de-Dôme, France). Rev Sci Nat Auvergne 76:39–52. Waldén HW. 1966. Einige Bemerkungen zum Erganzungsband zu Ehrmann’s “Mollusca”, in “Die Tierwelt Mitteleuropas”. Arch Moll 95(1/2):49–68. Wickham H. 2016. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York. ISBN 978-3-319-24277-4. Available at: https://ggplot2.tidyverse.org. Wood S. 2022. mgcv: Mixed GAM Computation Vehicle with Automatic Smoothness Estimation. R package version 1.8-41. Available at: https://CRAN.R-project.org/package=mgcv. Wright HE Jr, Ammann B, Stefanova I, Atanassova J, Margalitadze N, Wick L, Blyakharchuk T. 2003. Late-glacial and Early-Holocene Dry Climates from the Balkan Peninsula to Southern Siberia. In: Tonkov S (ed) Aspects of palynology and palaeoecology. Pensoft Publishing, Sofia, Moscow, BG. Supplementary materials Fig. S1. Generalized Linear Models (GLMs) performed on binary data (presence/absence) of all species and analysed environmental predictors. Shaded stripes indicate 95% confidence interval. Non-significant relationships and relationships explaining < 10% variation (Adj. R2) are faded. (download) Table S1. List of personal unpublished records. The list includes geographical coordinates, country, nearest settlement, description of locality, classification to fen category according to Hájek et al. (2006), date and name of the collector(s). (download) page 17 of 17Zoological Studies 63:19 (2024)