Gastropod Fauna Research Articles

Long‐term trends in gastropod abundance and biodiversity: Disentangling effects of press versus pulse disturbances

AbstractAimClimate‐induced pulse (e.g., hurricanes) and press (e.g., global warming) disturbances represent threats to populations, communities, and the ecosystem services that they provide. We leveraged three decades of annual data on tropical gastropods to quantify the effects of major hurricanes, associated secondary succession, and global warming on abundance, biodiversity, and species composition.LocationLuquillo Mountains, Puerto Rico.MethodsGastropod abundance, biodiversity, and composition were estimated annually for each of 27 years in a tropical montane forest that experienced three major hurricanes (Hugo, Georges, and Maria). Generalized linear mixed‐effects, linear mixed‐effects, and linear models evaluated population‐ and community‐level responses to year, ambient temperature, understorey temperature, hurricane, and time since hurricane. Variation partitioning determined the unique and shared variation in biotic responses associated with temperature, disturbance, and succession.ResultsRather than declining, gastropod abundances generally increased through time, whereas the responses of biodiversity were weak and scale dependent. Hurricanes and associated secondary succession, rather than ambient atmospheric temperature, moulded long‐term trends in abundances and biodiversity.Main conclusionsGlobal warming over the past 30 years has not progressed sufficiently to elicit significant responses by gastropods in the Luquillo Mountains. Rather, effects from pulse disturbances (i.e., hurricanes) and secondary succession currently drive long‐term variation in abundance and biodiversity. Gastropods evince high resilience in this tropical ecosystem. Historical exposure to recurrent hurricanes likely imbued the fauna with broad niches that make them resistant to current levels of global warming. We predict that biotic resiliency will be challenged once changes in temperature exceed interannual and inter‐habitat differences that typify this hurricane‐mediated system, or combine with an increased frequency of hurricanes and droughts to alter associations among environmental characteristics that define the fundamental niches of species. Only then might significant declines in abundance or the appearance of novel communities characterize the gastropod fauna in the Luquillo Mountains.

Non-marine gastropods from the Cretaceous–Paleogene transition in the Pingyi Basin, eastern China

Our results present a taxonomic and palaeoecological study on non-marine gastropods from the latest Cretaceous to Paleocene deposits of the Pingyi Basin, Shandong Province, eastern China. These gastropods are systematically described: three species belonging to three genera including Physa dongtaiensis Gu, 1989, Hydrobia datangensis Yü, 1977, and the newly established species Cyathopoma pingyiensis sp. nov.; two indeterminata genera and species including Truncatelloidea gen. et sp. indet., and Pomatiopsidae gen. et sp. indet. Among them, Truncatelloidea gen. et sp. indet. and Cyathopoma pingyiensis sp. nov. are the dominant species with the longest record. Cyathopoma pingyiensis, sp. nov. is the earliest representative of this widely distributed Asian extant genus. Sedimentological facies analysis of the gastropod-bearing beds suggested that Truncatelloidea gen. et sp. indet. lived in a small pond with a river inlet and a shallow lake, while Ph. dongtaiensis, ?Pomatiopsidae gen. et sp. indet, and ?H. datangensis only thrived in the shallow lake. Cyathopoma pingyiensis sp. nov. inhabited the land area around the shallow lake. Our results showed that no significant species change of the gastropod fauna across the K/Pg (Cretaceous/Paleogene) boundary was observed in the Pingyi Basin.

Hidden diversity revealed in the freshwater snails, Bythinella and Pseudamnicola, in the Island of Crete

Crete with its complex geomorphological history is the island with the highest number of endemism observed in animal and plant taxa throughout the Aegean archipelago. While other groups of organisms within Crete are well-studied, the freshwater gastropod fauna still remains poorly investigated. Bythinella and Pseudamnicola, are 2 genera of freshwater springsnails, both present on the island, inhabiting springs and other freshwater habitats. Here, we conduct a comprehensive study on the distribution of the different genetic lineages of the 2 gastropod genera in order to assess the mode of their differentiation on the island and infer the actual number of species present in the island. Towards these aims, sequence data from the mitochondrial gene were used and analyzed within a phylogenetic framework. For Bythinella, our results strongly support at least 5 delineated Bythinella spp. inhabiting Crete, which correspond to the already described species from previous studies with the addition of a new one. Bythinella analyses reveal an old time-frame of differentiation with vicariant phenomena being more likely the main drivers shaping the present-day distribution of the genus' genetic lineages. For Pseudamnicola, our data indicate the presence of at least 2 delineated Pseudamnicola spp. with a differentiation more consistent to an isolation-by-distance pattern of a relatively recent origin. Dispersion processes followed by isolation of the populations and/or recent speciation, seem to be the underlying process for the current distribution of Pseudamnicola lineages.

Gastropods from the Solimões Formation (upper Miocene), Acre Basin, Brazil

A taxonomic review of Miocene gastropods from the Solimões Formation, Acre Basin, Brazil, from specimens collected at Cachoeira do Bandeira, Oriente, and an outcrop named Spot 04, is here presented. Three ampullariid species (Pomacea maculata, P.planorbula, Pomacea sp.), one thiarid species (Aylacostoma sp.), and one cochliopid species (Sioliella sp.) are identified for these deposits. These gastropod are known to occur in freshwaters environments, thus consolidating the hypothesis of a non-influence of brackish water on the upper Miocene deposits of the Acre Basin. The previous identification of P. maculata and Aylacostoma sp. is changed here considering biometrical analyses and shell morphological descriptions. The first report of Sioliella in this basin increases the gastropod fauna known for these strata and expands the range of this genus. Keywords: Pomacea, Aylacostoma, Sioliella, Ampullariidae, Thiaridae, Cochliopidae.

Refinements on the fauna of shell-bearing prosobranch gastropods in the southern part of the Kara Sea

On the basis of material from the ZIN collection, as well as literature data, the species composition, taxonomic and biogeographic structure of the prosobranch gastropod fauna in the southern part of the Kara Sea were clarified. The analysis of the peculiarities of the distribution of gastropods of the Kara Sea by depth, temperature and salinity has been carried out. It has been established that the species composition of this fauna is extremely poor in comparison with other Arctic seas. It contains around 90 species belonging to 16 families. But at least 10 percent of them are represented by only single finds made on the border of the Kara Sea with other water areas. Therefore, it remains to be determined whether these species belong to the mollusk fauna of the Kara Sea. The biogeographic structure of the fauna turned out to be opposite to that described in the literature. Boreal species are absent, and the proportion of Atlantic species is much lower than that of the Pacific. It was also found that these two groups prefer different depths and are partially separated in space. The reasons for the separation of different biogeographical groups of gastropods in space and depth are not clear. It is assumed that the southern and northern parts of the sea are different faunal regions.

Slit-band gastropods (Pleurotomariida) from the Upper Triassic St. Cassian Formation and their diversity dynamics in the Triassic.

The St. Cassian Formation, Italy, has yielded the most diverse marine invertebrate fauna known from the Triassic. A quarter of all described Triassic gastropod species has been reported from this formation. Most of the gastropod species from the St. Cassian Formation were erected in the 19th century and many of them are known only from their original figures and descriptions. The failure to study type specimens resulted in many erroneous identifications by subsequent authors. Here, we revise the slit band gastropods (Pleurotomariida) from the St. Cassian Formationone of the major groups present in this formation. A total of 77 nominate Pleurotomariida species belonging to 29 genera and 11 families are present in the St. Cassian Formation which comprises approximately 14% of the total nominate gastropod species of that formation. In addition, we revise several taxa that had been wrongly assigned to Pleurotomariida. As other gastropod clades, Pleurotomariida experienced a major extinction at the end-Permian mass extinction event. As in the Late Palaeozoic, their relative abundance in gastropod faunas continued to be 30% in some Anisian faunas but decreased to 510% afterwards. Their diversification at generic level became interrupted by an extinction event within the Carnian, probably by the Carnian Pluvial Event. As a result of their sluggish recovery compared to the other gastropod groups, their species diversity decreased from 26% during the Permian to 18% during the Triassic. Type specimens of the following genera are studied: Proteomphalus, Rhaphistomella, Temnotropis, Kittlidiscus, Stuorella, Schizogonium, Wortheniella, Bandelium, Lancedellia, Rinaldoella, Pseudowortheniella, Paleunema, Ampezzalina, Bandelastraea, Cheilotomona, Pseudoscalites, Delphinulopsis, and Cochlearia. Nine new pleurotomariidan genera are erected: Amplitomaria, Pseudoananias, Lineacingulum, Pressulasphaera, Cancellotomaria, Acutitomaria, Lineaetomaria, Nodocingulum, and Striacingulum. Eight new species are described: Schizogonium undae, Acutitomaria kustatscherae, Wortheniella klipsteini, Wortheniella paolofedelei, Rinaldoella tornata, Nodocingulum ernstkittli, Nodocingulum? turris, and Laubella subsulcata. Eoworthenia frydai is a new replacement name for Worthenia rarissima Barrande.

Late Cretaceous hydrothermal vent communities from the Troodos ophiolite, Cyprus: systematics and evolutionary significance

AbstractModern hydrothermal vent communities are based on chemosynthesis by microbial primary producers. Molecular phylogenetic divergence estimates indicate that many of the dominant vent taxa arose during the Cenozoic and Cretaceous; however, the fossil record of vent communities from these time periods is poor. One occurrence of such Cretaceous vent communities pertains to six volcanogenic massive sulphide deposits in the Troodos ophiolite of Cyprus. These deposits represent hydrothermal activity on deep (2500–5000 m) arc‐related spreading ridge(s) in the Neotethyan Ocean over several million years during the late Cenomanian and earliest Turonian. The Cyprus vent communities consist of worm tubes, representing possible vestimentiferans and serpulids, together with a moderate diversity of abyssochrysoid gastropods, belonging to eight new species (Desbruyeresia kinousaensis sp. nov., Desbruyeresia memiensis sp. nov., Desbruyeresia kambiaensis sp. nov., Hokkaidoconcha morisseaui sp. nov., Ascheria canni sp. nov., Cyprioconcha robertsoni gen. et sp. nov., Paskentana xenophontosi sp. nov. and Paskentana dixoni sp. nov.) in five genera and three families; none of the species is shared between vent sites. A single gaudryceratid ammonite from one of the vent sites most likely represents a water‐logged shell that sank from surface waters. The gastropod fauna contains the first representatives of the genera Desbruyeresia, Hokkaidoconcha, Ascheria and Paskentana from hydrothermal vents, and also the youngest representative of the last‐named genus in any environment. The Cypriot vent communities share tube worms with slightly older (Cenomanian) and younger (Turonian–Santonian) vent communities elsewhere in the western part of the Neotethyan Ocean.

Two new species of the Balkan genus Paladilhiopsis Pavlović, 1913 (Caenogastropoda, Moitessieriidae).

The Balkan Peninsula is inhabited by the worldwide most diverse subterranean gastropod fauna. This fauna is still poorly studied, since its habitats are not easily accessible, and its sampled populations are mostly not rich in specimens’ numbers. Often only empty shells are known, but the shell is hardly useful, not only in phylogeny reconstruction, but even in species determination. The exclusively obligatory subterranean family Moitessieriidae is especially poorly studied. Representatives of the genus Paladilhiopsis Pavlović, 1913 (Moitessieriidae) collected at three localities, distributed in Croatia and Bosnia & Herzegovina, were studied. The pigmentation of their shells and soft parts, as well as the female and male reproductive organs in one taxon, are presented. The partial sequences of the molecular markers mitochondrial cytochrome oxidase subunit I (COI) and nuclear histone 3 (H3) were used to infer their systematic status and phylogenetic relationships. Two species new to science are described. For one of them, also studied anatomically, 15 specimens were sequenced for COI, and all show the same haplotype.

Gastropods from the Paso Hondo Formation (lower-middle Permian) of Chiapas, Mexico: Stratigraphical and paleobiogeographical considerations

The specimens herein studied were recollected in strata from the Paso Hondo Formation (lower-middle Permian), which are outcropping in the Chicomuselo region, southeast of Chiapas state, limiting with the frontier of Guatemala. The material studied consists of 13 species: four determined to a specific level (Bellerophon deflectus, Discotropis sulcifer, Omphalotrochus cochisensis, and Donaldospira geminocarinata), five conferred to other species (Warthia cf. W. welleri, Warthia cf. W. waageni, Euomphalus cf. E. kaibabensis, Worthenia cf. W. crenulata, and Glabrocingulum cf. G. coronatum), three described to genus level (Glyptospira sp., Naticopsis sp., and Stephanozyga sp.), and one assigned, doubtfully, to the genus Pharkidonotus. This community constitutes the most diverse gastropod fauna from the Permian of Chiapas known to date. Although the material is scarce and poorly preserved, the association allowed relating the age of the bearing rocks to the Kungurian-Roadian (late Cisuralian-early Guadalupian), coinciding with previous data obtained employing other invertebrates and fusulinids. Moreover, the taxa described can be associated with coeval marine faunas from the southern United States (Texas, New Mexico, and Arizona), which are recognized as geographical regions where the Grandian Province's biota was established. This information suggests that, during the early-middle Permian, those territories were connected with Chiapas through epicontinental seas formed in the equatorial region.

Сучасний стан та особливості таксономічної структури трематод прісноводних молюсків Українського Полісся

The paper presents results on the analysis of the taxonomic structure of the trematode fauna of the Ukrainian Polissia. It was found that the trematode fauna of freshwater molluscs in the Ukrainian Polissia is represented by 62 species. We supplemented the species composition of larvae of trematodes in the region with 23 species, 13 of which were first recorded in Ukraine. The results showed that the number of trematode species the definitive hosts of which are fishes have decreased. According to the obtained data, the most abundant trematode species of freshwater molluscs in the Ukrainian Polissia are those of the families Echinostomatidae, Plagiorchiidae, Diplostomidae, and Notocotylidae. The combined analysis of literature and original data revealed that in the basis of the regional trematode fauna of molluscs are species of the families Echinostomatidae (13 species) and Plagiorchiidae (10 species), which make up almost one-third of the total number of trematode larvae detected. A quite large portion of larvae belong to species of the families Notocotylidae (8 species), Strigeidae (7 species), Diplostomidae (5 species), and Haematolechidae (5 species). Most families (Diplodiscidae, Opisthorchiidae, Leucochloridiomorphidae, Prostogonimidae, Cathaemasiidae, Cyclocoelidae, Prohemistomatidae, and others) are represented only by 1–2 species. In freshwater molluscs of the studied region, we have found only 38 % of trematode species recorded in definitive hosts. Species found in vertebrate animals of the region potentially can also occur in intermediate hosts, but most of these species parasitize in birds that could be infected in other areas. When comparing the taxonomic structure of the trematode fauna of the Polissia with other well-studied regions of Ukraine (Northern Pryazovia and Crimea), some specifics were noted between them. In particular, it was found that the most abundant trematode species in the region as well as in the whole of Ukraine are those of the families Echinostomatidae, Plagiorchiidae, Diplostomidae, Notocotylidae, and Strigeidae. The obtained data allow considering that the trematode fauna of freshwater gastropods of the Ukrainian Polissia is an integral part of the Central European fauna of trematodes.

A diverse gastropod fauna from the shallow marine carbonate platform of the Yangou section (south China) in the immediate aftermath of the Permian–Triassic mass extinction

The Permian–Triassic mass extinction (PTME), the most devastating extinction event in Phanerozoic history, has witnessed the demise of almost 80% of marine gastropod genera. Despite the vast scale of the extinction event, the recovery of some groups of marine gastropods has been curiously fast, contrasting with the delayed recovery of many other marine clades. Understanding the rapid recovery of gastropods after the PTME represents a major palaeobiological conundrum, since oxygen‐dependent taxa are expected to have been severely impacted by anoxic oceanic conditions of the PTME. The controversial microbialite refuge hypothesis has been proposed as a potential explanation of this pattern, arguing that marine invertebrates were associated with oxygen‐producing microbial mats during the PTME, which provided a suitable microhabitat for survival within hostile anoxic conditions. To better understand the dynamics of gastropod recovery after the PTME, we studied a gastropod fauna collected from the basal Daye Formation (earliest Triassic) at the Yangou section in Leping County, Jiangxi Province, south China, allowing us to capture a snapshot of the marine fauna immediately after the PTME. Altogether, 13 microgastropod species belonging to 12 genera were recorded, representing the most diverse Induan (earliest Triassic) gastropod fauna in the world known to date. The fact that the Yangou assemblage, along with the second most diverse Griesbachian gastropod fauna from the Wadi Wasit section in Oman, is not associated with microbial buildups implies that microbial mats probably did not play a key role as refuges for marine invertebrates during the PTME. On the other hand, the Yangou fauna suggests that non‐anoxic shallow lagoon systems were more likely to have acted as refuges for marine invertebrates during the PTME.

A latest Cretaceous gastropod fauna from the Jiaolai Basin of East Asia

A non-marine gastropod fauna from the continuous uppermost Campanian to Maastrichtian deposits of the Jiaolai Basin (eastern North China) was studied. Four species attributed to four genera and an undetermined species were described, including Truncatella jiaozhouensis sp. nov., ?Pomatiopsidae gen. et sp. indet., ?Hydrobia datangensis Yü, 1977, Valvata jiaolaiensis sp. nov., and Physa sp. Among them, two new species were established. The finding of ?Hydrobia datangensis is consistent with a Late Cretaceous age as previously inferred from the charophyte flora. Available sedimentological data of the gastropod-bearing beds combined with a gastropod taphonomical study suggest that all five species lived in shallow lakes, whereas ?Pomatiopsidae gen. et sp. indet. also inhabited floodplains. Furthermore, extant Truncatella species are either fully terrestrial or dwell amphibiously in the supralittoral zone in temperate to tropical regions, usually close to the water line, as well as near freshwater of river estuaries. Therefore, Truncatella jiaozhouensis sp. nov. supposedly has lived in the surrounding shorelines of the shallow lake.

Malakofauna of the gissar reservoir and the gorge ilonli gissar ridge

The vertical profile was studied from the vicinity of the Gissarak reservoir to the east to the left tributary of the Gissar, then to the south and along the gorge. In many biotopes, they constitute a significant part of the communities of destructors of dead organic matter and phytophages. In turn, molluscs serve as food for many species of vertebrates and invertebrates, often making up a significant part of the diet. Currently, the fauna of terrestrial gastropods in Uzbekistan in general, and in the Gissar ridge, is extremely poorly studied. Only a few works are known. (A. Pazilova, F. Gaibnazarova).

Nuevos registros de moluscos (Gastropoda, Bivalvia) de la isla de Cozumel, Quintana Roo, Méxic

Background: Marine gastropods and bivalves are some of the most diverse invertebrate groups in nature, but in Mexico a better knowledge of their taxonomic composition is required. Although there are important studies on mollusks in the Mexican Caribbean, some areas such as Isla Cozumel have been barely studied. Goals: To identify new records of Cozumel marine gastropods and bivalves. Methods: The specimens were collected mainly from transects in sandy substrates and revision of rocky surfaces. Results: Eight families and eight genera were identified, from which six species of gastropods and three of bivalves are new records, which increases the knowledge of the marine malacofauna of the region. The new records represent 11.76% and 27.27% respectively of the total fauna of gastropods and marine bivalves known on the coasts of Isla Cozumel, which is 51 and 11 species for each of the two classes of mollusks. The main biogeographic affinity of the new records is the Caribbean. Conclusions: The study area has a 87.93% of the known marine gastropods for the state of Quintana Roo. The total marine bivalve species in the study area constitute 13.92% of the fauna of this mollusk class for the state. Although the main malacogeographic affinity of the new marine mollusk records is the Caribbean, the study area belongs to a transition zone with the Carolinean province. None of the new records is endemic. All the gastropod and bivalve species indicated as new records are can be found in at least four malacological subprovinces.

Early Jurassic (middle Hettangian) marine gastropods from the Pogibshi Formation (Alaska) and their paleobiogeographical significance

A middle Hettangian marine gastropod assemblage is reported from the Kenai Peninsula of south-central Alaska supplying new paleontological evidence of this group in Lower Jurassic rocks of North America. Pleurotomaria pogibshiensis sp. nov. is described from the middle Hettangian marine succession informally known as Pogibshi formation, being the first occurrence of the genus in the Kenai Peninsula and the oldest occurrence of the genus in present-day Alaska and North America. One species of the genus Lithotrochus, namely Lithotrochus humboldtii (von Buch), is also reported for the first time from the Kenai Peninsula. Lithotrochus has been considered as endemic to South America for a time range from the early Sinemurian to the late Pliensbachian. The newest occurrence of Lithotrochus in rocks of the Pogibshi formation extends the paleobiogeographical and chronostratigraphical distribution of the genus into the present-day Northern Hemisphere. However, the Southern Hemisphere affinities are consistent with the hypothetical interpretations (although supported both by paleobiogeographical and paleomagnetic data) that the Peninsular terrane of south-central Alaska is far-traveled and may have originated at much more southerly paleolatitudes than its present-day position. Two other Early Jurassic caenogastropods typical of the Andean region of South America and of the Tethyan epicontinental seas are described for the first time in the Pogibshi formation, and these are Pseudomelania sp. and Pictavia sp. The new gastropod assemblage reported here shows close affinities with coeval South American and European gastropod faunas, supplying new evidence to interpret their distribution during the Early Jurassic.

Methane Derived Authigenic Carbonate (MDAC) Aragonite Cemented Quaternary Hardground from a Methane Cold Seep, Rathlin Basin, Northern Ireland: δ13C and δ18O Isotopes, Environment, Porosity and Permeability

A block of sandstone retrieved by divers from near Rathlin Island, Co. Antrim, Northern Ireland, represents an aragonite cemented sand formed during the Quaternary. Strongly negative δ13C of the aragonite cement (−50 to −60‰ δ13C) indicates that the hardground was formed by the anaerobic oxidation of methane (AOM), resulting in the formation of a methane-derived authigenic carbonate (MDAC) hardground. Such hardgrounds have previously been recorded as forming extensive pavements in deeper waters in the mid Irish Sea (e.g., Croker Carbonate Slabs), although the latter also contains high-magnesium calcite. Sand was initially deposited as part of a storm lag deposit, with a reworked bivalve and gastropod fauna. This sand was then colonised by a probable crustacean fauna, producing horizontal open dwelling burrows (Thalassinoides). After aragonite cementation, the hardground was colonised by boring bivalves, with slightly negatively elevated levels of δ13C. Finally, the hardground was colonised by an encrusting fauna (bryozoans, calcareous algae and serpulids), by then in warmer seas. Continued depleted levels of δ13C present within the encrusting fauna (−1 to −5‰ δ13C) indicate continued methane generation and seepage, which may still be active to the present day, and to the possibility of shallow gas reserves. The δ18O values change between macro-infauna vs. encrusters, indicating a warming in water temperature, reflecting glacial and post-glacial environments. The aragonite cemented sandstone has a highly variable porosity, with large vugs (open burrows and borings), smaller mouldic porosity within gastropods and bivalves and complex micro-porosity associated with acicular aragonite cements. Overall permeability was recorded at the 2.5 to 23 Darcies level, reflecting the highly variable vuggy porosity, although matrix permeability was around 100 mD and controlled by the MDAC fabric. Actual permeability will likely be controlled by the extent to which larger pores are interconnected. The sea around the Rathlin Island area contains a diverse fauna, which is worthy of future study in the context of cold seep and MDAC pavement formation.

Checklist of the fresh and brackish water snails (Mollusca, Gastropoda) of Bénin and adjacent West African ecoregions

Currently no comprehensive checklist of fresh and brackish water gastropods from Bénin exists, and those for adjacent West African areas are outdated. Yet, such checklists provide essential biodiversity information and a consistent taxonomic and nomenclatural framework for that biodiversity. Here a first checklist of the fresh and brackish water gastropods from Bénin and adjacent West African ecoregions is presented, based on an extensive literature review and field surveys between September 2014 and June 2019 in six major fresh and brackish water ecosystems in Bénin. This inventory includes information on synonymy, species distribution in West Africa, habitats, and conservation status. The fresh and brackish water gastropod fauna includes 60 species, belonging to 28 genera and 16 families. Pachychilidae, Ampullariidae, Neritidae, and Bulinidae were the most diverse families with 9, 8, 7, and 7 species, respectively. However, literature and field data indicated that 23 species observed in West African basins that extend to Bénin do not occur in the territory of Bénin. These species were not detected in our field surveys, most likely because they are rare at collecting sites. Of the 60 species included, five are classified as “Data Deficient”, 43 as “Least Concern”, two as “Nearly Threatened”, one as “Vulnerable”, and six as “Endangered” by the IUCN, whereas the remaining three species were not evaluated. Because the taxonomy of fresh and brackish water gastropods in West Africa is still largely based on morphology, comparative molecular and taxonomic studies may result in substantial revisions of this checklist over the coming years.

Upper Toarcian (Lower Jurassic) marine gastropods from the Cleveland Basin, England: systematics, palaeobiogeography and contribution to biotic recovery from the early Toarcian extinction event

AbstractHere we describe a new upper Toarcian (Lower Jurassic) marine gastropod fauna from rocks of the Cleveland Basin exposed on the North Yorkshire coast of England. The fossil assemblage consists of 16 species, of which three are new:Katosira?bicarinatasp. nov.,Turritelloidea stephenisp. nov. andStriactaenonina eleganssp. nov. Four species are described in open nomenclature asTricarilda? sp.,Jurildasp.,Cylindrobullinasp. andCossmanninasp. The other species have previously been described:Coelodiscus minutus(SchüblerinZieten),Procerithium quadrilineatum(Römer),Pseudokatosira undulata(Benzinvon Zieten),Palaeorissoinaaff.acuminata(Gründel),Pietteia unicarinata(Hudleston),Globulariacf.canina(Hudleston),Striactaeoninacf.richterorumSchulbert & Nützel,Striactaenoninaaff.tenuistriata(Hudleston) andSulcoactaeon sedgvici(Phillips). Most of these species are the earliest records of their respective genera and show palaeobiogeographical connections with contemporary gastropod associations from other regions of Europe and South America. The taxonomic composition of the upper Toarcian Cleveland Basin gastropod assemblage differs substantially from the faunas of the upper Pliensbachian and lower ToarcianTenuicostatumZone, showing the strong effect of the early Toarcian mass extinction event on the marine gastropod communities in the basin. Only a few gastropod species are shared between the late Toarcian faunas and the much more diverse Aalenian gastropod faunas in the Cleveland Basin, suggesting that there was a facies control on gastropod occurrences at that time. This is also a potential explanation for the taxonomic differences between the late Toarcian gastropod faunas in the Cleveland Basin and those in France, and northern and southern Germany.

New additions to the freshwater gastropod fauna (Gastropoda: Hydrobiidae, Lymnaeidae) of Morocco

In this paper, we provide new additions to the freshwater gastropod fauna of Morocco. Pseudamnicola luteola (Küster, 1852) and the recently described Mercuria gauthieri Glöer, Bouzid & Boeters, 2010 are recorded for the first time in the country and the presence of Ecrobia vitrea (Risso 1826) as well as Radix labiata (Rossmässler, 1835) are confirmed. Photos of the species are presented, in addition to the map of their distribution area with the habitat descriptions.

Marine gastropods of Accra Beach, Barbados, North Atlantic Ocean

The widespread occurrence of marine gastropods in coastal regions is a straightforward evidence of successful adaptation to different environments. In the Caribbean Sea, as one of Conservation International’s biodiversity hotspots, little is known about the gastropod fauna, especially in the Eastern Caribbean. The present study contributed to bridge this gap by studying the biodiversity of gastropods from Accra Beach, Barbados. Throughout random collections in September 2015, we collected 321 gastropods, comprising eight species, distributed in three families (Neritidae: Nerita tessellata, N. fulgurans, N. versicolor and N. peloronta; Littorinidae: Echinolittorina ziczac, E. angustior and E. tuberculata; and Muricidae: Plicopurpura patula). Nerites were more abundant and diverse, highlighting N. tessellata, representing 66% of the sampled gastropods. This paper also reports the first record of N. fulgurans and E. angustior for the island of Barbados.