Cepaea Nemoralis Research Articles

Gastropod grazing on fresh and senescent leaves of non-native invasive plants Reynoutria japonica and Impatiensglandulifera

In invaded regions, the introduced non-native plants Reynoutria japonica and Impatiens glandulifera show little grazing damage, most likely due to the absence of specialized herbivores and the deterrent effect of secondary metabolites on generalist herbivores. The low degree of grazing damage has been explained by the non-mutually exclusive enemy-release and novel weapon hypotheses. We tested assumptions of these hypotheses by conducting a series of preference tests in which leaf samples from R. japonica, I. glandulifera, and the native Urtica dioica were offered to five species of generalist gastropods (the native Arianta arbustorum, Cepaea nemoralis and Fruticicola fruticum, and the non-native invasive Hygromia cinctella and Arion vulgaris). In addition, we determined the C/N-ratio and total phenolic compounds (as a surrogate of secondary metabolites) of the plant species. In the choice experiment with fresh leaf samples, all snail species showed a preference for U. dioica, with the exception of the non-native invasive slug A. vulgaris, which ate leaf tissue from I. gladulifera almost as much as from U. dioica. The snails’ preference of U. dioica was even more pronounced when the fresh weight of leaf material eaten was considered. No-choice tests with either fresh or dead R. japonica leaves showed that most individuals of all species ate small amounts of fresh leaves, but less of dead leaves. In contrast, no-choice tests with either fresh or senescent I. glandulifera leaf tissue showed that individuals of all five gastropod species consumed larger amounts of senescent leaves than fresh leaves, probably because secondary compounds have been broken down or leached or the leaf texture has changed. The low susceptibility of these non-native invasive plants to the gastropods can most likely be explained by a combination of chemical and physical plant characteristics.

Three Gastropod Species Reported in Utah for the First Time: Arion fasciatus, Cryptomastix magnidentata, and Cepaea nemoralis

Three Gastropod Species Reported in Utah for the First Time: Arion fasciatus, Cryptomastix magnidentata, and Cepaea nemoralis

Comparison of the Spreading History of Two Introduced Cepaea Species (Gastropoda, Helicidae) in Ukraine with Remarks on Their Phenotypic Variability

Trends of the current dispersal of Cepaea nemoralis and C. hortensis in Ukraine are analysed, which are closely related to the activities of several garden centres, which export a part of the sold seedlings of ornamental and garden plants from other European countries. Using Lviv and its environs as an example, we compared the qualitative and quantitative phenotypic composition of C. nemoralis at sites where both Cepaea species or only C. nemoralis were recently introduced. On average, the former were characterised by a greater phenotypic diversity of C. nemoralis, which may be due to a greater number of founding individuals of such colonies. At the sites of the second group, hereditary traits (brown ground colour, shell with three lower bands) or phenotypes (yellow unbanded), which are less common in the study area, were more often absent. Also, a clearly pronounced predominance of any one variant of the shell colouration was more often noted there, most often pink unbanded or yellow mid-banded.

Scientific and educational potential of the malacological collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine

The importance of the malacological collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv for the history and further development of malacological research in Ukraine is considered. The scientific potential of stock malacological materials, accumulated in the museum since the second half of the 19th century and significantly supplemented during the last decades, was analyzed in temporal and geographical aspects, as well as taking into account the taxonomic diversity and intraspecific conchological variability of the molluscs of Ukraine, the presence of typical materials, etc. It was found that the main (scientific) part of the malacological collection well represents the present land and freshwater mollusc fauna of Ukraine and its western part. Not represented in the museum's malacological collection are still some species that are mainly locally distributed in Ukraine and often have small sizes, which further complicates their sampling. Among the more recent additions to the malacological collection, we can especially mention the samples related to the study of the land mollusc fauna of the steppe zone of Ukraine, which remained poorly studied until the end of the 20th and even the beginning of the 21st century, as well as to the shell color and banding polymorphism in the Eastern European populations of two introduced species, Cepaea nemoralis and C. hortensis. Among the auxiliary part of the malacological collection, a large block of materials that can be used for exhibition purposes is selected. They allow demonstrating a wide range of topics from the taxonomic and morphological diversity of molluscs of Ukraine and the world to conchological adaptations. It can be useful when studying corresponding sections of a school biology course, as well as for students of biological specialties, amateur naturalists, etc. Various forms of virtual exhibiting allow to shown the public also numerous materials of the main (scientific) part of the malacological collection, which became possible within the framework of the Educational online program “Molluscs”. This allows us to talk about the gradual transformation of the main part of the malacological collection from a classical scientific collection to a scientific and educational one with virtual access.

New data on the distribution of anthropochorous species of land molluscs in western regions of Ukraine and possible approaches to their classification

On the basis of own data, materials transferred to the laboratory of malacology or the malacological collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv, as well as a critical analysis of observations in two citizen science databases (iNaturalist, UkrBIN), new records of some anthropochorous land mollusc species in Western Ukraine, and in particular, in Lviv and its immediate surroundings, are described. In tabular form, the temporal and spatial presence in the western part of Ukraine of 23 species that could appear here only due to anthropochory is analyzed. Maps of the findings of Cepaea nemoralis, Deroceras caucasicum, Oxychilus draparnaudi, and O. translucidus in and near Lviv are given. Known reliable localities of C. nemoralis in Volyn, Ivano-Frankivsk, Lviv, Rivne, Ternopil, and Khmelnytskyi regions are listed. Similar information is presented for the related species Cepaea hortensis from all administrative regions of Western Ukraine, except for Lviv region, where this species is widespread in settlements. According to the time of penetration into Western Ukraine, among the anthropochorous species of land molluscs, relatively recent invaders prevail, which were first reliably discovered not earlier than in the 1990s. At the turn of the 20th and 21st centuries, optimal conditions for the introduction and subsequent acclimatization in urbanized biotopes of many adventitious species of land molluscs, in particular thermophilic species of Mediterranean or Crimean origin, emerged in Western Ukraine. In addition to global warming, this was facilitated by the intensification of trade and transport links with other regions of Ukraine and other European countries, as well as the activities of garden centres. Besides the time of entry into the analyzed area, anthropochorous species of land molluscs can be classified according to the ways of this penetration (from other regions of Ukraine or from other European countries located to the west of it), the nature of their present distribution in Western Ukraine, as well as the ability or inability to enter natural biotopes outside settlements.

Fine mapping of the Cepaea nemoralis shell colour and mid-banded loci using a high-density linkage map

Molluscs are a highly speciose phylum that exhibits an astonishing array of colours and patterns, yet relatively little progress has been made in identifying the underlying genes that determine phenotypic variation. One prominent example is the land snail Cepaea nemoralis for which classical genetic studies have shown that around nine loci, several physically linked and inherited together as a ‘supergene’, control the shell colour and banding polymorphism. As a first step towards identifying the genes involved, we used whole-genome resequencing of individuals from a laboratory cross to construct a high-density linkage map, and then trait mapping to identify 95% confidence intervals for the chromosomal region that contains the supergene, specifically the colour locus (C), and the unlinked mid-banded locus (U). The linkage map is made up of 215,593 markers, ordered into 22 linkage groups, with one large group making up ~27% of the genome. The C locus was mapped to a ~1.3 cM region on linkage group 11, and the U locus was mapped to a ~0.7 cM region on linkage group 15. The linkage map will serve as an important resource for further evolutionary and population genomic studies of C. nemoralis and related species, as well as the identification of candidate genes within the supergene and for the mid-banding phenotype.

Disgusted snails, oxytocin, and the avoidance of infection threat

Disgust is considered to be a fundamental affective state associated with triggering the behavioral avoidance of infection and parasite/pathogen threat. In humans, and other vertebrates, disgust affects how individuals interact with, and respond to, parasites, pathogens and potentially infected conspecifics and their sensory cues. Here we show that the land snail, Cepaea nemoralis, displays a similar “disgust-like” state eliciting behavioral avoidance responses to the mucus associated cues of infected and potentially infected snails. Brief exposure to the mucus of snails treated with the Gram-negative bacterial endotoxin, lipopolysaccharide (LPS), elicited dose-related behavioral avoidance, including acute antinociceptive responses, similar to those expressed by mammals. In addition, exposure to the mucus cues of LPS treated snails led to a subsequent avoidance of unfamiliar individuals, paralleling the recognition of and avoidance responses exhibited by vertebrates exposed to potential pathogen risk. Further, the avoidance of, and antinociceptive responses to, the mucus of LPS treated snails were attenuated in a dose-related manner by the oxytocin (OT) receptor antagonist, L-368,899. This supports the involvement of OT and OT receptor homologs in the expression of infection avoidance, and consistent with the roles of OT in the modulation of responses to salient social and infection threats by rodents and other vertebrates. These findings with land snails are indicative of evolutionarily conserved disgust-like states associated with OT/OT receptor homolog modulated behavioral avoidance responses to infection and pathogen threat.

The First Finding of Cepaea nemoralis (Linnaeus, 1758) (Mollusca: Gastropoda: Helicidae) in Donbass and the Phenetic Structure of the Identified Colony

The First Finding of Cepaea nemoralis (Linnaeus, 1758) (Mollusca: Gastropoda: Helicidae) in Donbass and the Phenetic Structure of the Identified Colony

THE FIRST RECORD OF CEPAEA NEMORALIS (LINNAEUS, 1758) (MOLLUSCA: GASTROPODA: HELICIDAE) IN THE DONBASS AND THE PHENETIC STRUCTURE OF THE FOUND COLONY

The phenetic composition of Cepaea nemoralis (Linnaeus, 1758) (Mollusca: Gastropoda: Helicidae) colony found in an area of continuous high-rise buildings in the center of Donetsk in 2022 is described. The area of the colony is 2.5 ha, the number reaches 15 ind./m2, the age is at least 10 years. Individuals with a pink ground colours (81.5%) and one central band in 64.7% of yellow-coloured and 76.8% of pink-coloured shells are clearly dominated. The absence of unbanded shells and shells with reduced 1, 2, 4 and 5 bands was a distinctive feature of the Donetsk colony. The trend of dominance of phenotypes with fused bands is traced for five-banded shells with the relative frequency of 69.7%. Morphs with fusion types of bands, namely F(45) - 13.2% and F(23) - 12.8% dominate. The colony is characterized by a relatively high degree of polymorphism (𝜇 = 4.78±0.039) and proportion of rare morphs (h±𝑆ℎ = 0.47±0.026) showing no similarities with the colonies in Eastern Europe available for meta-analysis. Cepaea nemoralis is likely to remain one of the elements in the urban fauna, not showing any tendency to expand into natural ecosystems.

Differentiated extracts from freshwater and terrestrial mollusks inhibit virulence factor production in Cryptococcus neoformans

The human fungal pathogen, Cryptococcus neoformans, is responsible for deadly infections among immunocompromised individuals with the evolution of antifungal resistance driving the solution to discover new compounds that inhibit fungal virulence factors rather than kill the pathogen. Recently, exploration into natural sources (e.g., plants, invertebrates, microbes) of antifungal agents has garnered attention by integrating a One Health approach for new compound discovery. Here, we explore extracts from three mollusk species (freshwater and terrestrial) and evaluate effects against the growth and virulence factor production (i.e., thermotolerance, melanin, capsule, and biofilm) in C. neoformans. We demonstrate that clarified extracts of Planorbella pilsbryi have a fungicidal effect on cryptococcal cells comparable to fluconazole. Similarly, all extracts of Cipangopaludina chinensis affect cryptococcal thermotolerance and impair biofilm and capsule production, with clarified extracts of Cepaea nemoralis also conveying the latter effect. Next, inhibitory activity of extracts against peptidases related to specific virulence factors, combined with stress assays and quantitative proteomics, defined distinct proteome signatures and proposed proteins driving the observed anti-virulence properties. Overall, this work highlights the potential of compounds derived from natural sources to inhibit virulence factor production in a clinically important fungal pathogen.

Land snails can trap trematode cercariae in their shell: Encapsulation as a general response against parasites?

Terrestrial gastropods are hosts of a wide variety of metazoan parasites and can respond to parasite exposure in various ways. One of these defence mechanisms, the ability to trap parasites in the host shell, was previously thought to apply only against nematodes. During a field survey along an urbanisation gradient, we found that the shell of Cornu aspersum and Cepaea nemoralis can contain encapsulated trematode cercariae, with prevalences of 7% and 1%, respectively over the entire sample, and up to 47% at the local population level. To our knowledge, this is the first case study unambiguously showing that land snails can trap non-nematode parasites in their shell at non-negligible prevalences. Shell-encapsulation could be a more general defence mechanism than previously described, and more studies are needed to understand its importance and variability.

Morph‐dependent nematode infection and its association with host movement in the land snail Cepaea nemoralis (Mollusca, Gastropoda)

AbstractHost behaviour can be influenced by parasitic risk and infection through a variety of direct and indirect mechanisms. We can expect individuals expressing different phenotypes to also differ in the ways their behaviour is altered by parasites. We used the land snail Cepaea nemoralis, a species with various shell colour morphs differing in behaviour and physiology, as a model to study the link between parasite response and individual behaviour variation. We analysed metazoan parasite abundance and its relation to behaviour (movement and food intake) in snails from three shell morphs (from light unbanded to darker five‐banded) and from two neighbouring populations from contrasting environments. Snails were parasitized by mites, trematodes, and nematodes, from rarest to most frequent. We confirm that terrestrial gastropods can defend against infection by trapping parasitic nematodes in their shell. We show that nematodes encapsulated in shells can uncover past infections even when a snail population is currently nematode‐free, possibly due to parasite seasonality. We present new observations suggesting that not only nematodes but also mites might be encapsulated in shells. Infection levels varied between morphs, with darker snails harbouring fewer nematodes. Behaviour (movement and food intake) was linked to the nematode, but not trematode infection. Individuals with higher nematode load ate less, irrespective of morph and population. The most‐infected morph (unbanded snails) showed reduced activity in the nematode‐infected population compared to the one that was nematode‐free at sampling time. As a result, parasites may cancel previously described behavioural differences between morphs. We discuss the possible mechanisms explaining morph‐dependent responses to parasites, and how parasite risk may be an unseen force shaping C. nemoralis morph variation in space and time. We conclude with the possible ecological consequences of the link, mediated by shell colour, and between thermal and immune responses.

Comparative analysis of phenotypic variability of introduced land snail Cepaea nemoralis (Gastropoda: Helicidae) in two large Eastern European cities

Variation in the shell colour and banding polymorphism of Cepaea nemoralis was recorded in 20 sites in Minsk, Belarus (a total of 3965 adults collected in 2014–2021). This variation was compared with that in 16 sites from Lviv, Western Ukraine (total 3235 adults collected in 2019–2021). Unlike in Lviv, a remarkable spatial differentiation of the phenotypic composition was found in Minsk. The samples collected in the north-eastern part of Minsk were characterized by a greater degree of phenotypic diversity and by higher frequencies of unbanded and brown shells. Samples from the southern and eastern parts of the city were generally lighter and characterised by high frequencies of shells with a single central band (mid-banded). Differences between the two parts of Minsk were greater than those between Minsk and Lviv. This may be related to the history of colonization of Minsk by C. nemoralis. The Lviv samples were, on average, darker, they contained less frequently mid-banded shells and more frequently unbanded shells, especially pink unbanded ones. The Fst values characterizing the level of phenotypic variability and calculated for Minsk and Lviv are quite high and comparable with those for other urban areas recently colonized by C. nemoralis.

Deep structure, long-distance migration and admixture in the colour polymorphic land snail Cepaea nemoralis.

Although snails of the genus Cepaea have historically been important in studying colour polymorphism, an ongoing issue is that there is a lack of knowledge of the underlying genetics of the polymorphism, as well as an absence of genomic data to put findings in context. We, therefore, used phylogenomic methods to begin to investigate the post‐glacial history of Cepaea nemoralis, with a long‐term aim to understand the roles that selection and drift have in determining both European‐wide and local patterns of colour polymorphism. By combining prior and new mitochondrial DNA data from over 1500 individuals with ddRAD genomic data from representative individuals across Europe, we show that patterns of differentiation are primarily due to multiple deeply diverged populations of snails. Minimally, there is a widespread Central European population and additional diverged groups in Northern Spain, the Pyrenees, as well as likely Italy and South Eastern Europe. The genomic analysis showed that the present‐day snails in Ireland and possibly some other locations are likely descendants of admixture between snails from the Pyrenees and the Central European group, an observation that is consistent with prior inferences from mitochondrial DNA alone. The interpretation is that C. nemoralis may have arrived in Ireland via long‐distance migration from the Pyrenean region, subsequently admixing with arrivals from elsewhere. This work, therefore, provides a baseline expectation for future studies on the genetics of the colour polymorphism, as well as providing a comparator for similar species.

Level of oxidative stress for the land snail Cepaea nemoralis from aged and bioremediated soil contaminated with petroleum products.

Here, we investigated whether the widely distributed snail Cepaea nemoralis could be used as a suitable sentinel animal for assessing the effects of soil contaminants-petroleum oil derivatives-after years of soil ageing and treatment with a bacterial formulation. Oxidative stress was assessed in the foot and hepatopancreas of C. nemoralis L. exposed to soil contaminated with unleaded petrol, spent engine oil or diesel oil and bioremediated with a bacterial formulation (soil was used 2years after contamination and bioremediation process). We measured total antioxidant capacity, catalase and glutathione transferase activity and concentrations of superoxide anions, hydrogen peroxide and protein carbonyls in the foot and hepatopancreas of snails after 2 and 4weeks of treatment. The studied antioxidant responses appeared largely to be tissue and remediation process specific, while the concentrations of superoxide anions, hydrogen peroxide and protein carbonyls depended on time of exposure, tissue type and the type of contaminants, but mostly not on the remediation process. Generally, changes in the concentrations of superoxide anions, hydrogen peroxide and protein carbonyls in the hepatopancreas of snails seemed to be a suitable measure to assess the risk of animals exposed to soil contaminated with petroleum substances and used after many years of ageing and treatment with a microbial formulation.

Experimental evidence for snails dispersing tardigrades based on Milnesium inceptum and Cepaea nemoralis species

Dispersal abilities in animals contribute to their local genetic variability and species persistence. However, the mechanisms facilitating a short-distance migration of small organisms remain underexplored. In this study we experimentally tested the role of land snails for a fine-scale transmission of tardigrades. We also check the ecological relationship between these two groups, by testing the impact of snail's mucus on tardigrades in anhydrobiosis. All the experiments were conducted under laboratory conditions. As model organisms, we used a tardigrade species Milnesium inceptum and a snail species Cepaea nemoralis. The selection of the experimental animals was dictated by their co-occurrence in natural habitats and similar atmospheric conditions required for them to remain active. Results of our experiments support the assumption that snails may transfer active tardigrades for short distances. On the other hand, the effect of the snails mucus on tardigrade recovery to active life after anhydrobiosis was negative. Death rates of tardigrades in anhydrobiosis (tun) were higher when affected by mucus compared to mucus-free tuns.

First record of the grove snail Cepaea nemoralis (Gastropoda, Helicidae) in Ternopil region and specificity of the phenotypic composition of the found colony

The first finding of Cepaea nemoralis, an introduced species of land molluscs with polymorphic shell colouration, in the Ternopil region of Ukraine is described. Juveniles of this species were observed in Chortkiv already in 2017, but only in 2020 their exact species affiliation was identified, the presence of an established colony was confirmed and the peculiarities of its phenotypic composition were analyzed. The obtained data were compared with other colonies of the grove snail, which were found in Western Ukraine (Lviv and its environs, Bohorodchany in Ivano-Frankivsk region) in 2019-2020 and described in previous publications. Most of the conchological material collected in Chortkiv is deposited in the malacological collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv. In the Chortkiv colony of C. nemoralis, a hereditary trait was found, which occurs sporadically in the natural range of the grove snail, but has not yet been registered in Ukraine. This feature is manifested in the uneven pigmentation of dark spiral bands on the shell, the alternation of lighter and darker fragments on them, which can create the impression of spotted, interrupted bands. In the analyzed sample, such bands had 25.6% of banded shells, and they occurred twice as often in yellow (41.2%) than in pink (18.5%) shells. This agrees well with the known data on the linked inheritance of this trait and the ground colour of the shell. However, the shells with fused bands, regardless of their ground colour, almost always had normally pigmented bands, dark along their entire length. In some individuals with unevenly pigmented bands, the splitting of the fourth or fifth band into 2-3 narrow longitudinal bands was also observed. Another feature of the Chortkiv colony of C. nemoralis compared to other known Western Ukrainian colonies of this species is the very low frequencies of all lighter variants of the shell colouration (yellow and pink unbanded or with one central band) and a very high proportion of phenotypes with 3 lower bands (49.6%). The ratio of the main variants of the shell colouration of C. nemoralis in Chortkiv, which is not typical for Western Ukraine, makes the found colony a valuable object for studying potential adaptive changes in its phenotypic composition in the future.

History of the penetration of anthropochorous mollusc species to western Ukraine

Analysis of literary sources and materials of the malacological collection of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv revealed that at the end of the 19th century in western Ukraine could be present only some anthropochorous species of slugs, especially Limax maximus. Instead, mentions of a number of species not belonging to the indigenous malacofauna of Ukraine and its western region, made from the second half of the 19th to the middle of the 20th century, could most likely be based on the erroneous identification of other, native species. The process of intensive penetration into western Ukraine of alien species of land molluscs began, apparently, not earlier than the middle – second half of the 20th century and significantly accelerated at the turn of the 20th and 21st centuries. The latter could be due to both climate change, which facilitated adaptation to local climatic conditions for more thermophilic species, and the active import of seedlings of ornamental plants from other European countries. In particular, a dangerous pest from the complex Arion lusitanicus s.l. could enter the territory of Ukraine in this way. No less indicative are the relatively young colonies of Cepaea nemoralis, which are increasingly found in western Ukraine. Since the end of the 20th century, species of Caucasian origin and those that were previously observed only for the southern part of the country are increasingly registered in western Ukraine. Compared to the great taxonomic diversity of land anthropochorous molluscs and the widespread distribution of some of them, a relatively small number of freshwater species (up to 8), alien to this area, are still known in western Ukraine. For most of them, only a few finds are still known, made in the early 21st century. The exception is only one species (Physella acuta), which began to be mentioned for various areas in western Ukraine in the second half of the 20th century. Among the alien freshwater molluscs are a group of small species imported to Europe from other continents: New Zealand Potamopyrgus antipodarum, North American Menetus dilatatus, Physella heterostropha and possibly also Physa skinneri and Physella acuta. Representatives of the Dreissena genus came here from the Black Sea territories in the south of Ukraine.

Determination of selected biochemical parameters of the haemolymph of free-living Cepaea nemoralis (L.) snails. Preliminary study

The study objective was to determine reference values of selected biochemical parameters of the haemolymph of Cepaea nemoralis snails (Mollusca, Gastropoda, Helicidae). The study determined the activity of aminotransferases (AST and ALT), which was 11.22 ± 10.92 [u/l] and 6.72 ± 3.18 [u/l], respectively, and alkaline phosphatase (ALP) at a level of 3.92 ± 2.08 [u/l]. The level of amylase (AMY) in the haemolymph was 2.32 ± 0.74 [u/l], while lipase (LIP) was 0.74 ± 0.79 [u/l]. The concentration of urea (UREA) was established at 2.28 ± 0.48 [mg/dl], creatinine (CREA) at 2.28 ± 0.09 [mg/dl], uric acid (UA) at 0.22 ± 0.16 [mg/dl], calcium (Ca) at 21.24 ± 2.4 [mg/dl], and total protein (TP) at 1.38 ± 0.34 [g/l]. The specific gravity of the haemolymph was 1.0 ± 0.002. The haemolymph was obtained from 211 individuals in the active phase collected from their natural habitat. The biochemical parameters of the haemolymph were determined with a BS 180 apparatus (Mindray), and the specific gravity with a refractometer. The article also desrcibes an intravital technique of collecting haemolymph from C. nemoralis. The results obtained may constitute an aid and a guideline for scientists dealing with the physiology of land molluscs.

Terrestrial Snails and Slugs of Nevada, USA: An Overview of Taxa, Biogeography, and Habitat Affinities

The biogeography and habitat affinities of the Recent taxa of terrestrial mollusks of Nevada, western USA, are discussed herein. A total of 52 land snails and slug species were found in Nevada, of which 21 are newly reported records. Two native land snails found previously were not found by this author, and 6 additional species are possible for the state. Of the 47 species of land snail found in the state, 42 are considered native, while 5 are introduced. Only one slug, Deroceras laeve, is considered native, while 4 others are introduced. Land mollusks in eastern and central Nevada are derived from the Rocky Mountain Molluscan Province, such as Pupilla hebes, Microphysula ingersolli, and Oreohelix strigosa depressa (9 species, 18%), while southern Nevada supports species derived from the Southwestern Province, such as Gastrocopta spp., Striatura meridionalis, and Eremarionta rowelli (8 species, 16%). A Californian and Oregonian influence includes Pristiloma chersinella and Punctum californicum. Introduced land snails and slugs such as Deroceras reticulatum, Lehmannia valentiana, Cepaea nemoralis, and Rumina decollata are found in the gardens and parks of urban areas in Nevada. The present native land snail distributions in Nevada result from Miocene and Pliocene dispersal and establishment in the mountains of the Great Basin followed by Pleistocene and Holocene fragmentation and isolation. Xeric habitats such as sagebrush steppe, Pygmy conifer woodlands, and dry alkaline lake beds dominate much of the state and support very few or no land mollusks. Nine habitats are identified as being used by terrestrial mollusks in Nevada. Mountain woodlands, springs, and chaparral support 71% of the total fauna, which includes 36 land snail species and the slug Deroceras laeve where water, coniferous and deciduous vegetation, and moist litter are available between 1400 and 2800 m elevation. The more xeric Mojave Desert in the south (165–1100 m) and sagebrush steppe of the Great Basin (800–2000 m) support 3 and 4 species, respectively. The Pygmy coniferous woodlands occasionally support 2 species, except when the woodlands are associated with limestone cliffs and shrubs, where 5 species may be present (1600–2200 m). River valleys, perennial streams, and meadows (800–2000 m) make up only 1% of the state's land area but support 19 species of land mollusks. Subalpine and alpine habitats in the high mountains (2800–3400 m) support 13 species of land snails. Urban areas with greenhouses, parks, and casino gardens support 9 species of introduced land snails and slugs.