Gyraulus marocana sp. nov., a new freshwater snail species (Mollusca, Gastropoda, Planorbidae) from Morocco

A new planorbid gastropod species is described: Gyraulus marocana sp. nov. It can be distinguished from other known species by its regularly striated ivory shell, with four whorls separated by a deep suture, prostate gland with 20 diverticula, phallotheca twice as long as the preputium and its orange stylet. The new species was found in the northern part of Morocco, in Lake Zerrouka, a Protected Area, being also a site of ecological and biological interest (known as SIBE). It is located in the Middle Atlas massif, which is a geographical barrier known for its other endemic molluscs.

Synopsis of the terrestrial and freshwater gastropod fauna of southern Bahia, Brazil

The terrestrial and freshwater malacofauna of southern Bahia is little known, especially in comparison to the well-studied eastern portion of the state covered by remnants of Atlantic Forest. We present here a synopsis of all gastropod species known from the central southern region of Bahia state, known as ‘Centro-Sul Baiano’, focusing on four municipalities: Condeúba, Cordeiros, Mortugaba, and Piripá. The list herein contains data from the literature, historical material deposited in museum collections, and two recent expeditions undertaken in the region. The survey resulted in 21 species of gastropods, with nearly 700 voucher specimens (mostly freshwater) deposited in the collection of the Museu de Zoologia da Universidade de São Paulo (São Paulo, Brazil). Circa 30% of the species are non-indigenous; previously, the only known exotic in the region was Melanoides tuberculata (Müller, 1774). The family Achatinidae was the most diverse group in number of native species, while the typically diverse superfamily Orthalicoidea was represented by only two species.

Analysis of Gastropod Diversity as a Bioindicator of Waters in Situ Ciburuy Padalarang, West Bandung Regency, West Java, Indonesia

This study conducted to determine the water quality of Situ Ciburuy based on the structure of the gastropod community as a bioindicator. The survey method used in this study based on collecting data directly at the research area (purpose sampling method). For instance, species and density of gastropods were descriptively analyzed, using diversity index and evenes index. For instance, The findings showed that level of water quality in Situ Ciburuy based on gastropods bioindicators was lightly polluted. That is indicated by the low to moderate diversity of gastropods, which ranges from 1.31-1.98. The Shannon evenness index (0,73-0.95) revealed low gastropod species diversity in Situ Ciburuy, indicating low evenness of gastropod in Situ Ciburuy.

Association patterns of seagrass with gastropods types in the intertidal zone of coastal waters, Suli village, Salahutu district, Ambon island

Seagrass beds play an important role in coastal aquatic ecosystems and are one of the tidal areas that are widely used by the community as a forum for the interests of educational institutions in research activities, conservation of various marine biota. Ecologically, the seagrass ecosystem acts as a shelter and a place to eat various marine biota, including gastropods. The purpose of this research is not only to explore the diversity of gastropods, but also to examine the interactions of gastropod species, both between the same species and between different species in a community of seagrass ecosystems. The diversity index calculation shows the diversity index value H = 3.982 > 3, this means that the diversity of gastropod species is quite good. The results of the basic analysis obtained the calculated X2 value of 0.656, > X2 table with a significant level of 0.05%. There is an association relationship between seagrass ecosystems and the types of gastropods that live in seagrass ecosystems in coastal waters of Suli Village, Ambon. Keywords: Gastropods, Seagrass meadows, Association

Diversity and abundance of terrestrial gastropods in Skikda region (North-East Algeria): correlation with soil physicochemical factors

Background The inventory process is the first method to protect and safeguard animal biodiversity. This study carries out a quantitative and qualitative inventory of terrestrial gastropods at three sites in Skikda province (north-eastern Algeria). The relationship between terrestrial gastropod diversity and soil physicochemical factors was investigated using statistical analyses. Results The inventory data reveals the presence of four families and eight species showing varied predominance rates of Cornu aspersum species according to each site in the city of Skikda (Azzaba 53.88%; Ben-Azzouz 56.12%; El-Hadaiek 37.92%). The maximal specific richness was registered in the El-Hadaiek site (seven species), and the highest mean richness was noted in the Ben-Azzouz site (392 individuals). Of the eight gastropod species identified, three species (Cornu aspersum, Cantareus apertus and Rumina decollate) were classified as constant species. The Shannon–Weaver diversity and equitability indices vary by site. Conclusion The presence of certain species in one site and their absence in other sites, as well as the variation in ecological indices, could be attributed to the effect of soil-physicochemical factors.

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 Formation—one 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 5–10 % 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.

Phasmarhabditis quinamensis sp. n. (Nematoda: Rhabditidae) from tropical terrestrial gastropods in southern Vietnam

Summary Phasmarhabditis quinamensis sp. n. was recovered from several tropical terrestrial gastropod species collected in Cat Tien National Park in southern Vietnam with the snail, Sesara sp., designated as the type host. Phasmarhabditis quinamensis sp. n. is recognised by males and females with a lip region set off by the circle of six triangular low probolae, three bilobed, separated lips, stoma nearly as wide as long, the first genital papilla in males not incorporated into the bursa, the ensheathed dauer juveniles more than 1 mm long and with two circles of papillae at the head end and prominent amphidial apertures, a long filamentous tail and, when exsheathed, with a short, conical tail ending with two tiny spikes. The head structure of P. quinamensis sp. n. differentiates it from all nominal species of Phasmarhabditis. Phasmarhabditis quinamensis sp. n. is the second species of the genus found in Cat Tien National Park. The sympatric species P. meridionalis was also found during the present study. Phylogenetically, both species belong to different lineages within Phasmarhabditis. The molecular analysis based on partial sequences of LSU rDNA, and ITS rDNA regions showed P. kenyaensis to be the closest species to P. quinamensis sp. n.

MicroCT protocols for scanning of embryos and juvenile Hexaplex trunculus v1

Micro-computed tomography (micro-CT) is a high-resolution 3D-imaging technique which is now increasingly applied in biological studies focusing on taxonomy and functional morphology. The creation of virtual representations of specimens can increase availability of otherwise underexploited and inaccessible samples. This protocol aims to standardise micro-CT scanning procedures for embryos and juveniles of the marine gastropod species Hexaplex trunculus.

MicroCT protocols for scanning egg capsules of Hexaplex trunculus v1

Micro-computed tomography (micro-CT) is a high-resolution 3D-imaging technique which is now increasingly applied in biological studies focusing on taxonomy and functional morphology. The creation of virtual representations of specimens can increase availability of otherwise underexploited and inaccessible samples. This protocol aims to standardise micro-CT scanning procedures for the egg capsules of the marine gastropod species Hexaplex trunculus.

Negative assortative mating and maintenance of shell colour polymorphism in Littorina (Neritrema) species

Colour polymorphism is a widespread phenomenon in natural populations of several species. In particular, it is especially common on marine gastropod species from the genus Littorina. Recently, it has been argued that intrapopulation shell colour polymorphism in Littorina fabalis could be caused by negative frequency-dependent sexual selection via a mechanism of mate choice (indirectly estimated via negative assortative mating). Here we try to determine the existence of negative assortative mating in three species of the subgenus Neritrema (L. fabalis, L. obtusata, L. saxatilis) that share a similar shell colour polymorphism, in order to ascertain if this mechanism could represent an ancestral character in this subgenus that could be contributing to the maintenance of the colour polymorphism in each species. Here, we collected or reanalysed from previous studies a sample of mating pairs of the three species from seven locations from NW Spain and NE Russia and estimated assortative mating using the IPSI index. Our results show that all species and populations show a systematic tendency towards negative assortative mating when shell colour is grouped in the broad categories: ‘light’ and ‘dark’. Although, a more detailed analysis of each colour individually suggests that shell colour may not be the main target of assortative mating, but perhaps physically linked to another trait or through pleiotropic effects. This hypothesis opens interesting new lines of research in Littorina snails.