Snail Fauna Research Articles

Diversity and preserved shell coloration patterns of Miocene Conidae (Neogastropoda) from an exposure of the Gatun Formation, Colón Province, Panama

AbstractExtant members of the neogastropod family Conidae (cone snails) are renowned for their often dazzling shell coloration patterns and venomous feeding habits. Many cone snail species have also been described from the fossil record, but to date have been little used to understand the evolutionary history of extant clades. The cone snail fauna of the Miocene Gatun Formation of Colón Province, Panama is especially important for understanding the temporal and biogeographic history of tropical American Conidae. Intensive, focused collecting from an exposure of the lower Gatun Formation (deposited ca. 11–10 Ma) resulted in the discovery of nearly 900 specimens of Conidae. Remarkably, many of these well-preserved specimens exhibit revealed coloration patterns when exposed to ultraviolet light. The fluorescing coloration patterns were used in conjunction with other features of shell morphology to differentiate species and, in most cases, evaluate their potential relationships to members of the extant tropical American fauna. Nine species are fully described from this locality, one of which is recognized as new:Conus(Stephanoconus)woodringin. sp. At least one, and perhaps more, additional Conidae species are also present at the study locality. The diversity of this Conidae fauna is considered moderate relative to other recently analyzed tropical American fossil assemblages. The phylogenetic diversity of the assemblage, however, is noteworthy: six of the ten species can be confidently assigned to six different clades of extant Conidae, providing potentially useful calibration points for future phylogenetic studies.http://zoobank.org/8fe00c31-8f3f-4514-85af-29068e468cd3

The Australian Museum Lord Howe Island Expedition 2017—land snail fauna

Land snail surveys undertaken in 2016 and 2017 on Lord Howe Island by members of the Australian Museum have produced new occurrence records of at least 44 species of land snail. These include three probably species new as well as six introduced species.

Terrestrial Snail Fauna and Associated Helminth Parasites in a Tropical Semi-Urban Zone, Enugu State, Nigeria

Terrestrial Snail Fauna and Associated Helminth Parasites in a Tropical Semi-Urban Zone, Enugu State, Nigeria

Forest snail diversity and its environmental predictors along a sharp climatic gradient in southern Siberia

Diversity patterns of forest snail assemblages have been studied mainly in Europe. Siberian snail faunas have different evolutionary history and colonization dynamics than European faunas, but studies of forest snail diversity are almost missing from Siberia. Therefore, we collected snails at 173 forest sites in the Russian Altai and adjacent areas, encompassing broad variation in climate and forest types. We found 51 species, with a maximum of 15 and an average of seven species per site. The main gradient in species composition was related to soil pH, a variable that also positively correlates with snail abundances. The second gradient was associated with climate characteristics of winter. We observed significant differences in both species richness and composition among six forest types defined based on vegetation classification. Hemiboreal continental forests were the poorest of these types but hosted several species characteristic of European full-glacial stages of the Late Pleistocene. A high snow cover in Temperate coniferous and mixed forests, protecting the soil from freezing, allowed the frost-sensitive large-bodied (>10 mm) species to inhabit this forest type. In contrast to most of the European snail assemblages studied so far we found that the factors responsible for the variation in species richness differed from those driving species composition. This may be attributed to the sharp climatic gradient and the presence of the cold-adapted species typical of the Pleistocene cold stages. We suggest that southern Siberian forests hosting these species can serve as modern analogues of full-glacial forests in periglacial Central and Eastern Europe.

Clarification of the systematic position of Patula spatiosa Lindholm, 1922from eastern Turkey (Mollusca: Gastropoda).

One of the most mysterious taxa of the terrestrial snail fauna of Turkey is Patula spatiosa Lindholm, 1922. This large species has been described from a single specimen collected in 1914 allegedly in the Kars region (nowadays easternmost Turkey). Up to date, no further specimens have been reported. Its taxonomical position is unclear, even on the family level.

Protoconch sculpture as a taxonomic tool in Australian charopid systematics (Gastropoda: Eupulmonata: Charopidae)

ABSTRACTCharopidae represent one of the most speciose land snail faunas in Australia with an estimated 750 species, mostly being less than 5 mm in shell diameter. The majority of its species are undescribed. With limited available material suitable for molecular analysis, morphological methods remain the primary technique for the identification of charopid species, and recent studies have shown that the sculptural patterns on the protoconch are diagnostic in establishing a generic signature. This study attempts to establish a formal framework for the description of the protoconch patterns for those species currently considered to be members of the eastern Australian Gyrocochlea sensu lato (s.l.) group of charopids. The protoconch sculpture of 60 species and 72 putative species of Gyrocochlea s.l. were examined and grouped by sculptural pattern and location. Eleven major configurations are identified, defined and described. It is intended that this terminology will be the benchmark for future descriptions of the protoconch characteristics of Australian charopid species and their generic placement. Implications for the past generic allocation of some Gyrocochlea s.l. species are discussed. Evidence from this study also indicates that there is local geographic consistency in the distribution of the protoconch patterns and a broad latitudinal sequence of pattern turnover. The biogeographic implications of this are briefly explored.

Bellwether of the Canaries: anthropogenic effects on the land snail fauna of the Canary Islands

Natural areas near human-modified landscapes experience factors that may affect local biodiversity at levels commensurate with natural environmental factors. The land snails of the Canary Islands provide excellent opportunities to evaluate the importance of anthropogenic agents in mediating the diversity and distribution of species. Land snails are particularly sensitive to disturbance and are an integral part of terrestrial ecosystems. This study analyzed the distributions and abundances of terrestrial macrosnail shell assemblages at 60 localities throughout the coastal scrub biome of the Canary Islands. This was accomplished using data on natural and anthropogenic variables to assess their relative importance in governing land snail diversity. A total of 34,801 dead shells represented a diverse malacofauna with highly localized endemism. Due to uncertain species identifications, samples from the 18 sites from the two easternmost islands are described, but excluded from statistical analyses. Regression tree analysis indicated that proximity to agricultural sites was the most important predictor of species diversity. Sites with no or very little agricultural area (≤ 0.167 km2) within a 1 km radius had significantly higher richness and diversity. These results have implications for Canary Islands conservation. Protected areas that are patchworks of natural and agricultural landscapes are still subject to native biodiversity loss because of anthropogenic impacts even when the footprint of agriculture is small.

Snail fauna and investigations into the incidence of schistosoma infection in Lake of Oguta 1 Region, Imo State, Nigeria

A study aimed at identifying the current snail fauna of Oguta Lake in Oguta 1 of Oguta LGA, Imo State, was carried out between May 2012 and January 2013. Four sites were surveyed using standard scoop method consisting of flat wire mesh and iron handle. The species of snails were identified based on shell morphology. Out of 385 snails collected, 216 (56.1%) were Lymnaea , 150 (39.0%) Bulinus ; and 19 (4.9%) Pila . The spatial distribution of snails was clustered within two sites – Okpaosha and Onu Okpaosha out of the four-sites surveyed. There was no significant difference between the two sites where snails were collected ( p >0.05). More snails were recorded in the rainy season 304 (79%) than dry season 81 (20.9%). This study established the continuous presence of snail host species in Oguta Lake irrespective of dredging activities in the lake. The presence of snail host species indicates likely presence of urinary schistosomiasis among people living in the community, although none of the snails collected and exposed to sunlight was found to shed cercariae. Keywords: Freshwater; snail fauna; Oguta Lake; Imo State

Acidic, neutral and alkaline forest ponds as a landscape element affecting the biodiversity of freshwater snails

In recent years, the number of areas remaining under the influence of acidity has increased. At all levels of ecosystems, biodiversity decreases with acidification, due to the elimination of species that are most sensitive to low pH. Forest ponds belong to a specific group that varied in location, a huge amount of leaf litter, and isolation from other aquatic environments. They are crucial in the industrial landscape with well-developed industry and human activity. The aim was to investigate the relative importance of water chemistry in explaining snail assemblage compositions and species richness in forest ponds of contrasting pH. Patterns in gastropod communities were determined from an analysis in 26 forest ponds with multivariate gradient analysis. Ponds ranged in a base mean pH from 3.0 to 9.0. pH has been found to be an important factor influencing gastropod fauna. Neutral ponds support diverse communities, typical of small water bodies. In two acidic pond types, snail fauna was different. Among the species characteristic for acidic ponds (pH < 6) were Anisus spirorbis and Aplexa hypnorum. The greatest distinct characterised alkaline ponds with the numerous appearance of alien Physa acuta. The most diverse gastropod fauna was found in neutral ponds, whereas the lowest degree of diversity was found in ponds with the lowest pH. Current knowledge of pH-associated changes in aquatic ecosystems is still incomplete because anthropogenic acidification is a recent phenomenon. It is extremely important in forest habitats, since they react more intensively to climatic factors and are often used in landscape management and planning.

Quid est Clea helena? Evidence for a previously unrecognized radiation of assassin snails (Gastropoda: Buccinoidea: Nassariidae).

The genus Clea from SE Asia is from one of only two unrelated families among the megadiverse predatory marine Neogastropoda to have successfully conquered continental waters. While little is known about their anatomy, life history and ecology, interest has grown exponentially in recent years owing to their increasing popularity as aquarium pets. However, the systematic affinities of the genus and the validity of the included species have not been robustly explored. Differences in shell, operculum and radula characters support separation of Clea as presently defined into two distinct genera: Clea, for the type species Clea nigricans and its allies, and Anentome for Clea helena and allies. A five-gene mitochondrial (COI, 16S, 12S) and nuclear (H3, 28S) gene dataset confirms the placement of Anentome as a somewhat isolated offshoot of the family Nassariidae and sister to the estuarine Nassodonta. Anatomical data corroborate this grouping and, in conjunction with their phylogenetic placement, support their recognition as a new subfamily, the Anentominae. The assassin snail Anentome helena, a popular import through the aquarium trade so named for their voracious appetite for other snails, is found to comprise a complex of at least four species. None of these likely represents true Anentome helena described from Java, including a specimen purchased through the aquarium trade under this name in the US and one that was recently found introduced in Singapore, both of which were supported as conspecific with a species from Thailand. The introduction of Anentome “helena” through the aquarium trade constitutes a significant threat to native aquatic snail faunas which are often already highly imperiled. Comprehensive systematic revision of this previously unrecognized species complex is urgently needed to facilitate communication and manage this emerging threat.

Calcareous forest seepages acting as biodiversity hotspots and refugia for woodland snail faunas

Land-snail species richness has repeatedly been found to increase with the increasing site calcium content and humidity. These two factors, reported as the main drivers of land-snail assemblage diversity, are also among the main habitat characteristics of calcareous seepages. Here we explore local species richness and compositional variation of forest spring-fed patches (i.e. seepages), to test the hypothesis that these habitats might act as biodiversity hotspots and refugia of regional snail faunas. In contrast to treeless spring fens, only little is known about land snail faunas inhabiting forest seepages. Studying 25 isolated calcareous forest seepages, evenly distributed across the White Carpathians Protected Landscape Area (SE Czech Republic), we found that these sites, albeit spatially very limited, can harbour up to 66% of the shelled land-snail species known to occur in this well-explored protected area (in total 83 species). By comparing land snail assemblages of the studied seepages with those occurring in the woodland surroundings of each site as well as those previously sampled in 28 preserved forest sites within the study area, we found the seepages to be among the most species rich sites. Although the numbers of species did not statistically differ among these three systems, we found highly significant differences in species composition. Seepage faunas were composed of many species significantly associated with spring sites, in contrast to the assemblages of both surrounding and preserved forest sites. Our results highly support the hypothesis that calcareous forest seepages might serve as refugia and biodiversity hotspots of regional land snail faunas. Protection of these unique habitats challenges both conservation plans and forest management guidelines as they might act as sources for the recolonization and restoration of forest snail assemblages particularly in areas impoverished by harvesting and clearcutting.

Type Specimens of Hawaiian Land Snails in the Smithsonian Institution, National Museum of Natural History, with Lectotype Designations

Pacific island land snail faunas are among the most threatened faunas in the world, having suffered a higher rate of extinction than any other major animal group. The Hawaiian land snails are among the most species-rich and most severely effected of these faunas, yet the current status of most of the Hawaiian species is unknown. Most of the major taxonomic studies on the fauna were undertaken 50–100 years ago and only certain groups were comprehensively studied. New research is uncovering undescribed species, both extant and extinct. The need for rigorous taxonomic treatment of the group is acute if the taxonomic and conservation status of the many species is to be ascertained, and the basis for such research is comprehensive study of type material. The Smithsonian's National Museum of Natural History holds type material of 39 nominal species-group taxa of Hawaiian land snails belonging to eight families; this annotated catalog provides details of this material. Of these taxa, 29 were described by Augustus Addison Gould from material collected by the U.S. Exploring Expedition of 1838–1842. For completeness, we also provide details for one lot of purported paralectotypes that are here inferred not to have been syntypes and one lot representing an unavailable infrasubspecific name. We designate lectotypes for 12 species-group taxa . Yeung, Norine W., Robert H. Cowie, Kenneth A. Hayes, and Ellen E. Strong. Type Specimens of Hawaiian Land Snails in the Smithsonian Institution, National Museum of Natural History, with Lectotype Designations. Smithsonian Contributions to Zoology, number 647 , vi + 34 pages, 11 figures, 2017.

Diversity and taxonomy of Vietnamese Pollicaria (Gastropoda, Pupinidae)

Species in the genus Pollicaria (Gastropoda: Pupinidae) are conspicuous members of the southeast Asian land snail fauna. Originally erected in 1856, both the genus and its constituent species have been reorganized multiple times with the most recent treatment published in 2013. Collections of Vietnamese Pollicaria during 2014 and 2015 raised questions of the utility of currently used diagnostic shell characters and identification keys in species identification. An examination of the authors’ collections, combined with museum specimens, suggested that at least three species of Pollicaria occur or have historically occurred in Vietnam. It is suggested that P. rochebruni is a senior synonym of P. crossei and treat both taxa as conspecific. A second species, P. mouhoti, was believed to only occur in Cambodia, Laos, and Thailand. A possible third species, based only on previous karyotypic work, is discussed. Our data further suggest that shell features such as color and size lack consistent utility in species-level identifications in Pollicaria.

Distribution of intermediate host snails of schistosomiasis and fascioliasis in relation to environmental factors during the dry season in the Tchologo region, Côte d’Ivoire

Snail-borne trematodiases, such as fascioliasis and schistosomiasis, belong to the neglected tropical diseases; yet, millions of people and livestock are affected. The spatial and temporal distribution of intermediate host snails plays an important role in the epidemiology and control of trematodiases. Snail distribution is influenced by numerous environmental and anthropomorphic factors. The aim of this study was to assess the distribution and constitution of the snail fauna during the dry season in constructed and natural water bodies in the Tchologo region, northern Côte d’Ivoire, and to relate these findings to environmental factors and human infections. Snails were collected using standard procedures and environmental parameters were assessed from a total of 50 water bodies in and around 30 randomly selected villages. A canonical correspondence analysis was performed to establish the relationship between snail occurrence and environmental factors. Furthermore, a total of 743 people from the same 30 villages and nearby settlements were invited for stool and urine examination for the diagnosis of Fasciola spp., Schistosoma haematobium and Schistosoma mansoni. Snails of medical importance of the genera Biomphalaria, Bulinus, Lymnaea and Physa were found. Differences in snail occurrence from sites sampled in December 2014 and snails sampled in February 2015, as well as between the northern and southern part of the study area, were revealed. Various environmental factors, such as temperature and human activities, were related to the occurrence of intermediate host snail species in the region. Only 2.3% of human participants tested positive for schistosomiasis, while no Fasciola eggs were found in stool samples. We conclude that intermediate host snails of Fasciola and Schistosoma co-occur in water bodies in the Tchologo region and that the distribution of these snails correlates not only with environmental factors, but also with the presence of humans and animals and the environmental contamination of their excreta.

Měkkýši přírodní rezervace U Nového hradu a přilehlé zříceniny (Česká republika) [Molluscs of the U Nového hradu Nature Reserve and the nearby castle ruins (Czech Republic)

This study deals with the land snails in the U Nového hradu Nature Reserve and the nearby castle ruins. The main goal was to make an inventory of the snail fauna and to determine factors affecting species diversity and snail abundance. Further, species richness and composition of the assemblages in the Nature Reserve and the castle ruins were analysed and compared. Snails were collected in summer 2015 by hand picking and litter sampling at 14 quadrats; 10 in the Nature Reserve and four in the castle ruins. In each quadrat plant cover, amount of coarse trees and stones were recorded. Soil pH and conductivity values were measured at each plot. In total, 50 species and 675 individuals of snails were found in all quadrats combined. In the Nature Reserve, 43 species and 406 individuals were recorded. In the castle ruins, there were 33 species and 264 individuals found. On average, higher number of species and individuals per plot were found in the castle ruins than in the reserve. Soil pH was the only variable significantly and positive correlating with the number of snail species recorded. This variable also predicted higher local species richness in the castle ruins than that of the reserve. Based on MDS ordination there was no clear segregation of snail assemblages recorded in the reserve and the castle ruins, though sites from the ruins were more similar to each other that those from the reserve.

The River Valleys as Biodiversity Reservoirs for Land Snails in Highly Anthropic Areas – The Case of Cisnădie River (Romania)

Abstract This study focuses on the snail fauna of a river valley passing through two closely located settlements. Thirty six species of terrestrial gastropods were identified. Species such as Macrogastra borealis, Alinda fallax, Alinda viridana, Bulgarica vetusta, Monachoides vicinus, Drobacia banatica, are present along the river and abundant in the sampling stations downstream of Cisnădie town. The high specific diversity and the presence of typical forest species demonstrate the presence of fragments of habitat that can preserve populations of terrestrial gastropods, underlining the importance of river valleys in conservation and dispersion of these species.

Paleobiogeography of Early/Middle Miocene terrestrial gastropods in Central Europe: An approach using similarity indices

Terrestrial gastropods are a common faunal element in continental Miocene fossil Lagerstätten of Europe. Although having lived during a time span that includes the Miocene Climatic Optimum and the devastating Ries/Steinheim meteorite impacts, the state of knowledge about their faunal composition and geographic distribution is surprisingly incomplete. The land snail faunas of 30 different Early and Middle Miocene deposits of Central Europe (European Mammal Neogene zones MN 4 to MN 8) were compared using statistical methods (cluster and NMDS analyses, using the Ochiai, Simpson and Kulczynski indices). This includes 300 different taxa identified so far. Most of the analyzed deposits were part of the Miocene Paratethys and are today located in France, SW Germany (Baden-Württemberg state), SE Germany (Bavaria state), Austria, Poland, and Hungary. Cluster analyses resulted in different clusters, the majority of which can be explained by their geographic situation and/or by their distribution in time (e.g., the consistently recovered Baden-Württemberg and Bavaria clusters and the Bakony Mountains cluster). The remaining clusters cannot be fully explained so far, but some possibilities are explored here. Our results reveal the power of a solid taxonomic framework as a basis for palaeobiogeographic studies. As such, more “basic” palaeontological studies are required to strengthen future analyses.

Drivers of Central European urban land snail faunas: the role of climate and local species pool in the representation of native and non-native species

The importance of macroclimate and dispersal limitation in the broad-scale variation of European urban land snail assemblages is likely to differ between native and non-native species because of the southern origin of many non-native snails, often spread by humans. We sampled land snails in each of 32 European cities and compiled from the literature a list of land snail species reported from the surroundings of each city. To quantify the predictive power of climate and local species pools, beta-sim dissimilarity matrices of both native and non-native species were explored using MDS and RDA ordination methods, Mantel tests with bootstrapping of each dataset, and multivariate homogeneity analysis of group variances. We observed no significant relation between the numbers of non-native species found in the cities and their surroundings (p > 0.133), while the percentage of native species in the cities derived from their local species pools decreased significantly with the increasing species richness of local faunas (rS = −0.75, p < 0.001). Assemblage variation of urban native species was explained mostly by the difference between mean January and July temperatures (21.3 %), with the major role of July temperature (18.0 %). In contrast, variation of non-native species assemblages was mainly explained by January temperature (19.9 %). The congruence in faunal similarities between the cities and the surrounding areas was higher in native (r = 0.46, p < 0.001) than in non-native species (r = 0.36, p < 0.001). Overall native faunas were significantly more homogeneous than the non-native faunas. Our results suggest that recent climate warming may foster geographical expansions of many non-native land snail species as their distributions are controlled mainly by January temperature.

Annotated catalogue of types of Hawaiian land and freshwater snails (Mollusca: Gastropoda) in the Muséum national d'Histoire naturelle, Paris, with lectotype designations

ABSTRACT Pacific island land snail faunas are among the most threatened faunas in the world, having suffered a higher rate of extinction than any other major animal group. The Hawaiian land snails are among the most species rich and most severely impacted of these faunas, yet the current status of most of the Hawaiian species is unknown. Most of the major taxonomic studies on the fauna were under-taken 50–100 years ago and only certain groups were comprehensively revised. New research is uncovering undescribed species, both extant and extinct. The need for rigorous taxonomic treatment of the group is acute if the validity and conservation status of the many species is to be ascertained, and the basis for such research is comprehensive study of type material. The Museum national d'Histoire naturelle, Paris, holds type material of 38 nominal species-group taxa of Hawaiian land and freshwater snails belonging to six families, overwhelmingly the Achatinellidae Gulick, 1873 and Amastridae Pilsbry, 1910; this a...

Discordance between morphological and taxonomic diversity: land snails of oceanic archipelagos

AbstractAimMorphological and taxonomic diversity are intuitive measures of biological diversity. Previous studies have shown discordance between these measures at large spatial and temporal scales, but the implications of this pattern for the underlying processes are not understood. Using oceanic archipelagos as spatial units, we examine potential links between the morphological and taxonomic diversity of their land snail faunas in a biogeographical framework.LocationEleven major oceanic archipelagos.MethodsFor each archipelago, we assembled lists of indigenous land snail species, classified by family and genus, with shell height and width for each species (1723 species in total). We used biogeographic and climatic variables as potential predictors of diversity patterns. We employed regression analyses to evaluate (1) whether morphological diversity scales with taxonomic diversity at the species, genus or family level, and (2) whether morphological and taxonomic diversity correlate similarly with biogeographic/climatic factors. We also assessed which taxonomic level contributes most to morphological variation within archipelagos.ResultsMorphological diversity across archipelagos was strongly related to genus but not species richness. Within archipelagos, morphological variation reflected differences among genera and families but not species. Species richness was best explained by archipelago area, but morphological diversity was not significantly related to any of the physical features of archipelagos.Main conclusionsAcross archipelagos, species richness and morphological diversity of land snail faunas are decoupled. The relationship between species richness and the available ecological space (captured mainly by area) indicates the prevalence of niche‐based processes while, for morphological diversity, the strong conservatism of morphology at the genus level suggests the presence of diversification‐based limits. Assuming genera effectively reflect diversification, our findings indicate that morphological space on oceanic archipelagos depends primarily on the number of evolutionary units that have colonized and/or diversified through time.