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Variation in snail shell shape has provided evolutionary biologists with excellent material for the study of local adaptation to local environments. However, the assumption that shell shape variation is evidence of distinct lineages (species) might have led to taxonomic inflation within some gastropod lineages. Here, we compare shell shape variation and genetic structure of two independent lineages of New Zealand rocky shore whelks in order to understand the process that leads to an unusual disjunct distribution. We examined the Buccinulum vittatum complex (three subspecies plus Buccinulum colensoi) using mitochondrial DNA sequences, 849 single nucleotide polymorphisms and geometric morphometric data on shell shape. Specimens within the range of B. colensoi shared nuclear markers and mitochondrial DNA haplotypes with the southern subspecies Buccinulum vittatum littorinoides, whereas the northern samples (Buccinulum vittatum vittatum) had distinct genotypes. We infer that gene flow between B. colensoi and B. v. littorinoides is greater than between either of these taxa and B. v. vittatum. The distinctive shell sculpturing of B. colensoi is maintained despite gene flow, suggesting a role for selection. Although the shell form of B. colensoi appears to be an adaptation to local conditions, we did not observe convergent evolution in the sympatric whelk species Cominella maculosa. [ABSTRACT FROM AUTHOR]

Recent years have seen an increase in the number of studies that use DNA sequence information in addition to morphological methods, as the latter alone can be inadequate for morphologically similar, cryptic species. Marine onchidiid slugs (Mollusca: Gastropoda: Onchidiidae), which commonly inhabit intertidal environments and have a near-global distribution, comprise 11 genera and 86 described species. Singapore has 19 recorded species of onchidiids with Peronia verruculata (Cuvier, 1830) being the most abundant. Here we present mitochondrial DNA sequence data from 63 P. verruculatalike specimens to show that they constitute two closely-related clades with distinct sequence signatures and a clear barcode gap. Intraclade distances are 0-1.8% while interclade distances range from 4.7 to 6.0%. Scanning electron microscopy of internal copulation organs reveals that the two clades have distinct penial and accessory gland spine structures, which also differ in size. Using an integrative taxonomic approach, we propose that what was initially thought to be P. verruculata in Singapore, actually are two different species of Peronia. [ABSTRACT FROM AUTHOR]

Our work is a contribution to the study of the morphometric dissimilarity of the limpet Patella caerulea (Linnaeus, 1758) inhabiting the seashore of the western Mediterranean Sea. For this study, 438 individuals of this species were sampled in 24 stations and separated into 2 groups of individuals: the first group (G1) originating from the upper infralittoral and the lower mediolittoral areas, and the second group (G2) originating from the upper mediolittoral area. The biometry of P. caerulea has been studied by considering the total length (L), the total width (W), and the total height (H) of the shell. These parameters revealed a strong positive correlation, and were used for the principal component analysis (PCA). Other combined parameters (L/W, L/H, and W/H) were added for the discriminant function analysis (DFA). Both multivariate analyses showed that both groups (G1 and G2) were well separated. The morphometric survey based on the calculation of the geometric mean (GM) and the gibbosity index (GIB) revealed the existence of a morphological dissimilarity between the shells of groups G1 (flattened and stocky) and G2 (high and short). This morphological dissimilarity is discussed and compared with the results of other works on the same species and other related species. [ABSTRACT FROM AUTHOR]

Zetela is a genus of marine gastropods belonging to the family Solariellidae (Vetigastropoda, Trochoidea). The species Zetela alphonsi Vilvens, 2002 was originally described using classical conchological characters from samples obtained from deep water off Chiloé, Chile, but no other features were recorded in the original description. In the present paper, taxonomically relevant characters such as the operculum, radula, and soft part anatomy are illustrated and described for the first time from a specimen of Zetela alphonsi from a new locality, a methane seep area off the coast of central Chile. We find that many features differ substantially from other members of the genus, including several which deviate from characters that are diagnostic for Zetela. Zetela alphonsi also lacks retinal screening pigment, giving the appearance of eyelessness from gross examination. Although pigmentation loss has been reported in other deep sea genera, this feature has not been reported in any other members of Zetela. We reconstructed a tomographic model of the eye and eyestalk, and demonstrate that a vestigial eye is still present but externally invisible due to the loss of pigmentation. Based on these new morphological characters, particularly observations of the radula, we suggest that the current placement of this species in the genus Zetela should be reconsidered. [ABSTRACT FROM AUTHOR]

Background. The deep-sea hydrothermal vent is one of the most ‘extreme’ environments in the marine realm. Few species are capable of inhabiting such ecosystems, despite extremely high productivity there supported by microbial chemosynthesis, leading to high biomass and low species richness. Although gastropod molluscs are one of the main constituents of megafaunal communities at vent ecosystems, most species belong to several typical families (e.g., Provannidae, Peltospiridae, Lepetodrilidae) specialised and adapted to life at vents. Methods. During recent surveys of Okinawa Trough hydrothermal vent systems, two snails atypical of vent ecosystems were unexpectedly found in newly discovered hydrothermally influenced areas. Shell and radular characteristics were used to identify the gastropods morphologically. Results. One species was a vetigastropod, the calliostomatid Tristichotrochus ikukoae (Sakurai, 1994); and the other was a caenogastropod, the muricid Abyssotrophon soyoae (Okutani, 1959). Both gastropods were previously only known from regular non-chemosynthetic deep-sea and very rare—only two definitive published records exist for T. ikukoae and three for A. soyoae. The radula formula of Tristichotrochus ikukoae is accurately reported for the first time and based on that it is returned to genus Otukaia. For both species, barcode sequences of the cytochrome c oxidase I (COI) gene were obtained and deposited for future references. Discussion. These new records represent the second record of calliostomatids from vents (third from chemosynthetic ecosystems) and the third record of muricids from vents (tenth from chemosynthetic ecosystems), and extend the distribution of both species to the southwest. Neither family has been recorded at chemosynthetic ecosystems in the western Pacific. Both were from weakly diffuse flow areas not subject to high temperature venting but were nevertheless associated with typical vent-reliant taxa such as Lamellibrachia tubeworms and Bathymodiolus mussels. These new records show that these species are capable of tolerating environmental stress associated with weak hydrothermally influenced areas, despite not being vent endemic species, adding to the list of known vent/non-vent species intersections. This signifies that such weakly influenced areas may provide key habitats for them, and that such areas may play a role in the evolution of biological adaptations to ‘extreme’ chemosynthetic ecosystems. [ABSTRACT FROM AUTHOR]

The edible neogastropod Buccinanops cochlidium from Patagonia, Argentina, reproduces by means of egg capsules attached by the female to its own shell. Gravid females lay an outstanding mean of 500,000 eggs that nurse around 800 embryos, which hatch as crawling juveniles (4 mm in shell length) after four months of intracapsular development. This reproductive investment could be expressed as the energy content (EC) estimated for the production of a complete egg mass (33.94 ± 12.85 KJ), representing a conservative estimation of the total EC needed for an adult female to spawn, which is in average ∼12% of the total EC in gravid females. This high maternal investment allows a considerable offspring size, which confers them high survival chances. A translocation of energy stored in the foot during the oviposition season is shown in a relative decrease of ∼10% in the foot EC in respect of the total EC (61.8% in non-gravid females vs. 51.3% in gravid females). Gravid females showed significantly higher body wet mass/shell length index and higher total EC than non-gravid females (266.0 ± 66.4 KJ vs. 184.3 ± 69.6 KJ), suggesting that a body condition threshold is required for females to reproduce. These values represent an energetic surplus of over 40% of the total EC per individual when compared to non-gravid females. Protecting gravid females from fisheries would ensure the sustainability of the resource and must be taken into account when establishing fisheries policies. [ABSTRACT FROM AUTHOR]

Functional diversity based on species traits is a powerful tool to investigate how changes in species richness and composition affect ecosystem functioning. However, studies aimed at understanding changes in functional diversity over large temporal and spatial scales are still scant. Here we evaluate the combined effect of diversification and species sorting on functional diversity of fossil marine gastropods during the Pliocene-Quaternary transition in the Pacific coast of South America. We analyzed a total of 172 species in 29 Pliocene and 97 Quaternary sites. Each species was characterized according to six functional traits: body size, feeding type, mobility, attachment, life-habit, and larval mode. Functional diversity was estimated according to four indexes (functional richness, evenness, divergence and dispersion) based on functional traits measured. Extrapolated species richness showed a slight yet not significant decrease from the Pliocene to the Quaternary despite the fact that a large faunal turnover took place; furthermore, a large extinction of Pliocene species (61–76%) was followed by a high pulse of appearances (49–56%) during the Quaternary. Three out of four indices of functional diversity (evenness, divergence and dispersion) increased significantly towards the Quaternary which is more than expected under a random turnover of species. The increase in functional diversity is associated with a loss of large-sized carnivore forms, which tended to be replaced by small-sized grazers. Hence, this trait-selective species turnover, even in the absence of significant changes in species richness, likely had a large effect and has shaped the functional diversity of present-day assemblages. [ABSTRACT FROM AUTHOR]

This study focuses on the inter- and intra-specific variability in d13C and d18O values of shells and opercula of gastropods sampled live from the littoral zone of Lake Lednica, western Poland. The δ13C and δ18O values were measured in individual opercula of Bithynia tentaculata and in shells of Bithynia tentaculata, Gyraulus albus, Gyraulus crista, Lymnaea sp., Physa fontinalis, Radix auricularia, Theodoxus fluviatilis and Valvata cristata. The gastropods selected for the study are among the species most commonly found in European Quaternary lacustrine sediments. The carbon isotope composition of the gastropod shells was species-specific and the same order of species from the most to the least 13C-depleted was observed at all sites sampled. Differences in shell δ13C values between species were similar at all sampling sites, thus the factors influencing shell isotopic composition were interpreted as species-specific. The δ18O values of shells were similar in all the species investigated. Significant intra-specific variability in shell δ13C and δ18O values was observed not only within the populations of Lake Lednica, which can be explained by heterogeneity of δ13C DIC, δ18O water and water temperature between the sites where macrophytes with snails attached were sampled, but also between individuals sampled from restricted areas of the lake's bottom. The latter points to the importance of factors related to the ontogeny of individual gastropods. [ABSTRACT FROM AUTHOR]

A total of 11 species and 1 subspecies of Alycaeus were recognised in Peninsular Malaysia prior to this study. However, these taxonomic descriptions of Alycaeus taxa were based on limited numbers of examined materials, where a whole spectrum of morphological variations were not accounted for and diagnoses were often provided without sufficient comparison between congeners from across the peninsula. We reviewed Peninsular Malaysian Alycaeus through the examination of 5137 specimens in 522 collection lots from all major museum collections and literature sources. Based on these examined materials, we utilised a more comprehensive revised set of 39 shell and operculum characters, as well as living animal colour to describe all Alycaeus species in this paper. We also noted their habitat and ecology, as well as updated the distribution of each species. Of the 12 previously described taxa, 10 are reconfirmed as present on Peninsular Malaysia (Alycaeus balingensis, Alycaeus carinata, Alycaeus conformis, Alycaeus gibbosulus, Alycaeus kapayanensis, Alycaeus kelantanensis, Alycaeus liratulus, Alycaeus perakensis perakensis, Alycaeus perakensis altispirus and Alycaeus thieroti) and 2 are confirmed as absent from the peninsula (Alycaeus jagori and Alycaeus pyramidalis). A new record of Alycaeus robeleni is reported for Peninsular Malaysia. One species, Chamalycaeus jousseaumei is confirmed as present on the peninsula and is reassigned to Alycaeus. The subspecies Alycaeus perakensis altispirus Mollendorff, 1902, is elevated to species. Examined Peninsular Malaysian materials that do not fit previously recognised species are described as new species. A total of 11 new species are proposed (Alycaeus selangoriensis sp. n., Alycaeus costacrassa sp. n., Alycaeus ikanensis sp. n., Alycaeus alticola sp. n., Alycaeus charasensis sp. n., Alycaeus kurauensis sp. n., Alycaeus regalis sp. n., Alycaeus virgogravida sp. n., Alycaeus senyumensis sp. n., Alycaeus expansus sp. n., Alycaeus clementsi sp. n.). Overall, 23 species of Alycaeus are now recognised in Peninsular Malaysia. [ABSTRACT FROM AUTHOR]

Oviposition by Lymnaea stagnalis (L.) on shells of conspecifics has been reported anecdotally from laboratory observations. In order to gain the first quantitative insight into this behaviour, we have quantified the proportion of individuals bearing egg clutches in a long-term monospecific outdoor laboratory culture of L. stagnalis during two consecutive late-summer months. The snails were assigned to size classes based on shell height. Differences between the size class composition of clutch-bearers and of the general population were statistically compared by means of Pearson's distance χ2 P analysis. Egg clutches were laid on snails of shell height >15 mm (i.e. reproductive-age individuals), with significant selection for the larger size classes (shell height 25-40 mm). While the mechanisms of and reasons behind such behaviour remain unknown, selection of larger adults as egg-carriers may have ecological implications at the population level. [ABSTRACT FROM AUTHOR]

A new diplommatinid genus, Luzonocoptis Páll-Gergely & Hunyadi, gen. n. is erected for two new species, Luzonocoptis antenna Páll-Gergely & Hunyadi, sp. n. and L. angulata Páll-Gergely & Hunyadi, sp. n. Both species inhabit the northeastern part of Luzon Island, Philippines. The genus Luzonocoptis gen. n. is mostly characterized by a very slender shell with 14-18 whorls, a strongly expanded peristome, an interrupted, weak columellar lamella, the absence of any additional plicae or lamellae, and a rachidian tooth having five cusps. [ABSTRACT FROM AUTHOR]

Sabah, a Malaysian state at the north-eastern tip of Borneo, is situated in one of the Earth's biodiversity hotspots yet its freshwater gastropod diversity remains poorly known. An annotated checklist of the freshwater gastropods is presented, based on specimens deposited in the BORNEENSIS collection of the Institute for Tropical Biology and Conservation at Universiti Malaysia Sabah, Malaysia. A KMZ file is also provided, which acts as a repository of digital images and complete collection data of all examined material, so that it can be shared and adapted to facilitate future research. [ABSTRACT FROM AUTHOR]

The limpet form - a cap-shaped or slipper-shaped univalved shell - convergently evolved in many gastropod lineages, but questions remain about when, how often, and under which circumstances it originated. Except for some predation-resistant limpets in shallow-water marine environments, limpets are not well adapted to intense competition and predation, leading to the prediction that they originated in refugial habitats where exposure to predators and competitors is low. A survey of fossil and living limpets indicates that the limpet form evolved independently in at least 54 lineages, with particularly frequent origins in early-diverging gastropod clades, as well as in Neritimorpha and Heterobranchia. There are at least 14 origins in freshwater and 10 in the deep sea, with known times ranging from the Cambrian to the Neogene. Shallow-water limpets are most diverse at midlatitudes; predation-resistant taxa are rare in cold water and absent in freshwater. These patterns contrast with the mainly Late Cretaceous and Caenozoic warm-water origins of features such as the labral tooth, enveloped shell, varices, and burrowing-enhancing sculpture that confer defensive and competitive benefits on molluscs. [ABSTRACT FROM AUTHOR]

Sperm morphology offers a rich source of potentially informative characters for gastropod taxonomy and in this study it was used to provide additional information forGyraulus(Armiger)crista(Linnaeus, 1758), whose taxonomic position within the Planorbidae Rafinesque, 1815 remains uncertain. Sperm morphology inG. (A.)cristaandG. (Gyraulus)albus(Müller, 1774), the type species of the genus, was examined using light microscopy, scanning electron microscopy and transmission electron microscopy. The ultrastructure of spermatozoa in the two species was found to conform to the general pattern characteristic of the Hygrophila Férussac, 1822: the spermatozoa had an anterior head containing an acrosomal complex (apical vesicle and acrosomal pedestal) and cone-shaped nucleus, followed by a very long midpiece with glycogen spirals, and then by a glycogen piece and tail. Although the spermatozoa of the two species shared some common features (one nuclear keel and four glycogen spirals), they differed significantly in length, morphology of the annulus and structure of the spiral surface ridges. There were also some differences in the size and structure of the acrosomal pedestal and the shape of the nucleus. The spermatozoa of the twoGyraulusspecies are compared with those of other Hygrophila and the possible importance of sperm morphology for the taxonomic status ofG. (A.)cristais discussed. [ABSTRACT FROM AUTHOR]

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Chandipur intertidal flat in eastern coast of India is a killing field. The vast stretch of intertidal habitat opens up during the low tide, and is monopolized by a single naticid species which preys extensively on intertidal taxa. The predator, Natica tigrina , wades through the soft sediments and ambushes on epi- or infaunal prey. There were reports on naticid subaerial hunting, where the workers made vivid observations, but only in few instances quantified different aspects of predation. Detailed quantitative analyses of the present study revealed that N. tigrina attacks opportunistically on all infaunal and epifaunal intertidal bivalve and gastropod prey taxa. Drilling frequencies ranged from 9.70% to 67.67% with no apparent relation with relative abundances of the taxa. High drilling frequency on conspecific predation perhaps suggested elimination of the potential competitor as well as a profitable prey. Behavioral data of predation, i.e., stereotypy of site and size of drillholes on prey shells and low prey effectiveness indicated that the predator was highly efficient. [ABSTRACT FROM AUTHOR]

A new, most probably holoplanktonic gastropod genus and species, Freboldia fluitans Nützel & Schneider, is reported from the Early Jurassic (Pliensbachian) of Ellesmere Island, Canadian Arctic. Its shell is very thin, small, with a maximum diameter of 8 mm, inflated, planispiral and almost bilaterally symmetric, with deep umbilici. Hundreds of specimens of Freboldia occur in the matrix of transported siltstone concretions. In summary, these characteristics suggest a holoplanktonic lifestyle for Freboldia. Similar shells are present in the modern holoplanktonic gastropod family Limacinidae and in Cretaceous Bellerophinidae, and the new species is assigned to the latter family. The oldest records of holoplanktonic or pelagic gastropods are represented now by seven Early Jurassic genera: Coelodiscus, Tatediscus, Costasphaera, Pterotrachea, Simoniceras, Globorilusopsis and the new genus Freboldia. These are attributed to five different clades, which made their appearance at approximately the same time. We thus speculate that Early Jurassic anoxia triggered the rapid evolution of the holoplanktonic lifestyle in gastropods. [ABSTRACT FROM AUTHOR]

In recent years, several morphological and molecular analyses have been undertaken to study the phylogenetic systematics of Aeolidiidae members. The monospecific genus Burnaia could not be included in the previous analysis, due to the lack of material. This study includes two specimens of Burnaia helicochorda from Australia and places them in their systematic position using two mitochondrial and one nuclear genes (COI and 16S, and H3, respectively). A description of its anatomy is also included with colour pictures of the animal and scanning electron micrographs of radula and jaws. Based on our results, B. helicochorda does not belong to Aeolidiidae since it appears nested among some facelinids. [ABSTRACT FROM AUTHOR]

The family Chilinidae in Argentina has been thought to include 19 species. We provide new information on the shells, radulae, reproductive and nervous systems, and the molecular genetics of the chilinid species from the Cuyo Malacological Province (as defined by Núñez, V., Gutiérrez Gregoric, D.E. & Rumi, A. (2010) Freshwater gastropod provinces from Argentina.Malacologia53, 47–60), along with the description of two new species.Chilina sanjuaninan. sp. is characterized by a small shell with a conical and low spire and with one columellar tooth, a radula with an asymmetric central bicuspid tooth, and a penis sheath with an inner sculpture with regular conical pustules over the entire surface.Chilina cuyanan. sp. has a small shell with a low spire and two columellar teeth and a radula with an asymmetric tricuspid central tooth with serrated edges. The other two species in this province,Chilina mendozanaandChilina parchappii, are redescribed. Mitochondrial gene cytochrome c oxidase subunit I sequences betweenC. sanjuaninaandC. mendozanadiffer by 4%. [ABSTRACT FROM PUBLISHER]

Patellogastropod limpets are a widespread and extensively studied taxa, and yet comparisons between species and geographic regions are rare; instead, results are often generalized across these differences. This study investigated patterns of head orientation inPatellaspecies at four locations in the UK. The proportion of downwards facing limpets was also compared between areas in two locations with and without barnacles. Regardless of location, there was a strong downwards bias in orientation and the proportion of downwards facing limpets did not differ in the presence of barnacles. The results are compared with patterns of orientation exhibited by the Australian patellogastropodCellana tramoserica;this suggests that malacologists should be more cautious in extrapolating patterns of behaviour and distribution between species of patellogastropods and across regions. [ABSTRACT FROM PUBLISHER]

Cerithium koperbergi is a rare gastropod of the family Cerithiidae from the tropical Indo-West Pacific. The species has a small, unusual shell and often inhabits deeper water, fore-reef habitats that are atypical for the genus. Anatomical investigations reveal that it possesses a combination of features heretofore considered diagnostic of two main cerithiid subfamilies: Cerithiinae and Bittiinae. While the shell is bittiine, the animal lacks mesopodial pedal glands and possesses a seminal receptacle (vs. a spermatophore bursa) in the lateral lamina of the oviduct, which are considered to be cerithiine features. Re-evaluation of the anatomy of Bittium reticulatum, the type species of Bittium, indicates the defining anatomical difference in oviduct anatomy between the two subfamilies does not stand up to closer scrutiny. Partial mitochondrial cytochrome c oxidase I (COI) sequences support the interpretation that C. koperbergi is a species complex around the western Pacific rim comprising three divergent mitochondrial lineages. Bayesian analysis of partial mitochondrial COI and 16S rRNA sequences confirm the placement of the C. koperbergi complex within a monophyletic Bittiinae, despite the apparent absence of a unifying anatomical feature. Species in the C. koperbergi complex are here united in Pictorium nov. gen. and two species are described as new. It is hypothesized that features of the midgut may be diagnostic of the Bittiinae, but more comparative data are needed. [ABSTRACT FROM AUTHOR]

A new cassid species of the genus Phalium Link, 1807 is described from material trawled in the Sunda Shelf. Phalium pseudobandatum, new species, is superficially close to P. bandatum (Perry, 1811) because of similarities in shell colour and markings. However, the new species can be separated from P. bandatum by conchological characteristics. The position of the posterior sinus in the new species is at or extends above the shoulder, accompanied by a low spire with a side profile that is smooth and not step-like. It also has a less rotund body whorl with a more angular shoulder compared to P. bandatum. A distinct groove on the parietal shield where it adjoins the body whorl is also present on shells of the new species. In addition, the thickened middle part of the outer lip is not seen in similarly sized specimens of P. bandatum. The siphonal canal of the new species is not pigmented, and the crenulations at the anterior edge of the outer lip are more numerous but less distinct than in P. bandatum. We also suggest that P. exaratum (Reeve, 1848) is a distinct Indian Ocean species rather than a geographical subspecies of P. bandatum. [ABSTRACT FROM AUTHOR]

The genital anatomy of Orcula jetschini (Romania), O. zilchi (Bulgaria) and O. wagneri (Albania) is described. Based on anatomical features (morphology of the penial caecum), shell characters (sculpture and shape) and unpublished molecular data, the genus Orcula is subdivided into three subgenera. O. zilchi was classified within the monotypic subgenus Orcula (Hausdorfia) subgen. n.; O. jetschini, O. wagneri and O. schmidtii were classified to Orcula (Illyriobanatica) subgen. n. (type species: Pupa Schmidtii), whereas the other Orcula species remain in the nominotypical subgenus. Orcula (Hausdorfia) is known from South-Eastern Bulgaria and North-Western Turkey, Orcula (Illyriobanatica) inhabits Western Romania, North-Western Greece, Albania, Macedonia, Kosovo and Montenegro. The nine species of Orcula (Orcula) are known mainly from the Alps and the Western Carpathians (from Eastern France to Eastern Hungary and Slovakia). The occurrence of only one Orcula species, namely O. jetschini is verified from Romania. Available information suggests that data on the Romanian occurrence of Orcula dolium and O. gularis were based on wrongly identified specimens. Sphyradium dobrogicum (=Orcula dobrogica) is considered as a synonym of S. doliolum. [ABSTRACT FROM AUTHOR]

Abstract: Imposex, a syndrome characterized by the appearance of a penis and/or vas deferens in female gastropods due the presence of organotins in environment, is still observed in Brazilian gastropod populations, as in other countries, even after the tributyltin (TBT) ban. Nevertheless, the progressive controls on the use of organotins in antifouling systems at national and international levels and the consequent reduction of their environmental concentrations have led to changes in the characteristics of imposex development observed in Stramonita haemastoma. Populations of this species were analyzed on the coast of Rio de Janeiro (Brazil) between 2007 and 2008, and the developmental pathways associated with the syndrome were identified. Compared with previous works, it was noted that imposex expression was reduced in most of Guanabara Bay. Aphallic imposex development, on the other hand, showed a marked increase. The pathways of imposex development were also evaluated in a temporal data series from a fixed sampling station at Vermelha beach, and the incidence of aphallic imposex development was found to show a marked increase from 1998 onward. Furthermore, the observation of either the presence or absence of a penis in imposex-affected females may indicate that penis development is related to the contaminant exposure level and that the decreasing TBT concentrations in the local environment result in the predominance of an aphallic route of imposex development. These findings support the idea that imposex female aphally in this species could be a dose-dependent response, rather than a genetic anomaly. [Copyright &y& Elsevier]

Karucia sublacustrina a new species of freshwater snails (Hydrobiidae, Gastropoda) is described based on material collected from Skadar Lake (Montenegro, Albania). The new species belongs to monotypic genus Karucia gen. n. The shell morphology and body shape of the new genus resembles Radomaniola Szarowska, 2006 and Grossuana Radoman, 1973, from which it differs in the larger shells with relatively slim and a slightly, but clearly shouldered body whorl. The number of gastropods from Skadar Lake basin tallies now 50 species. The adjusted rate of gastropod endemicity for Skadar Lake basin is estimated to be 38%. By compiling faunal and taxonomic data we also aim to provide information of relevance as to conservation efforts. [ABSTRACT FROM AUTHOR]

Abstract: The structure of the gastropod Murex troscheli shell was investigated by using high-resolution scanning and transmission electron microscopies and high-resolution synchrotron X-ray powder diffraction. Rietveld refinement of X-ray diffraction patterns revealed anisotropic distortions of the orthorhombic aragonite unit cell, reaching a maximum of about 0.2% (along the c-direction) with respect to geological aragonite. Lattice distortions are effectively relieved under mild annealing at temperatures between 150°C and 250°C. This relaxation correlated well with the loss of organic substance during annealing, measured by thermal gravimetric analysis. The shell ultrastructure consists of three orders of hierarchy, which is typical for crossed-lamellar layers. The third-order fiber-like lamellae, nearly 50×250nm2 in cross-section, are heavily twinned, producing specific contrast features in transmission electron microscopy micrographs. So, higher orders of hierarchy are, in fact, twins, which boundaries are free of organic matter. [Copyright &y& Elsevier]

Abstract: The aim of the present study is to characterize the fecundity of the land hermit crab Coenobita scaevola as well as the influence of shell type on fecundity using morphometric relationships. Hermit crabs were collected monthly from January to December 2007 from the protected area of Wadi El-Gemal, at Marsa Alam on the Red Sea, and ovigerous females were selected. Hermit crab wet weight and the gastropod shell weight were recorded. The number of eggs carried by females of several sizes (CL, carapace length), stages of development and egg size were determined. Shells of eight gastropod species were occupied by ovigerous females of C. scaevola. Shells of Nerita undata was the most occupied (65.7%), particularly by individuals falling within the size range 5.0–7.0mm CL. Only 35 berried females were recorded during May, July and September and the mean fecundity was 679.8±140 eggs. Fecundity was found positively correlated with crab size and shell dimensions. The relationship between fecundity and the internal volume of the occupied shell was ranked as the most correlated. The impact of shell utilization on hermit crab fecundity is discussed. [Copyright &y& Elsevier]

Abstract: Directional orientation of Clibanarius signatus toward different targets of gastropod shells was studied in a circular arena upon exposure to background seawater, calcium concentrations and predatory odor. Directional orientation was absent when crabs were presented with the white background alone. Each shell was tested in different positions (e.g., anterior, posterior, upside-down, lateral). Adult crabs were tested without their gastropod shells, and orientation varied with concentration and chemical cue. With calcium, orientation increased as concentration increased up to a maximum attraction percentage and then attraction became stable. In the case of predator cues, some individuals swim away from the target toward the opposite direction representing a predator avoidance response. Whenever, the blind hermit crab C. signatus was exposed to a shell target combined with calcium or predator cues, the majority of them stop moving or move in circles around the arena center. The others exhibited uniform orientation distribution. The responsiveness was higher with calcium cues than predator cues. Thus in the absence of vision, individual hermit crabs were able to detect both calcium and predator cues and have different response regarding them. [Copyright &y& Elsevier]

A total of six genera and 10 species of marine gastropods belonging to the family Epitoniidae were collected from dredges of the continental slope off Brazil during the development of the REVIZEE (Live Resources of the Economic Exclusive Zone) Program. These species, referable to the genera Alora, Amaea, Cycloscala, Epitonium, Gregorioiscala, and Opalia, are reported from bathyal depths off northeastern Brazil. Alora sp., Gregorioiscala pimentai n. sp., and Opalia revizee n. sp. are species heretofore unknown to science. A list of the species of Epitonium and Opalia from the Atlantic coast of South America is presented based primarily on data from the literature. In addition, an overview of the biodiversity and distribution of the genera studied is presented for the Atlantic Ocean. [ABSTRACT FROM AUTHOR]

Background: Estuaries and coastal lakes receive little attention despite being heavily invaded by non-indigenous invasive species (NIS). In these situations, studies of population dynamics in invaded habitats can provide valuable insights into how NIS interact with new environments. Tarebia granifera is a prosobranch gastropod from south-east Asia which has invaded other sub-tropical parts of the world. This study addresses whether a small number of key environmental factors influences gastropod communities, and specifically how the population density and size structure of T. granifera were influenced by environmental change in estuaries and coastal lakes in southern Africa. Methodology/Principal Findings: T. granifera's density, number of brooded juveniles and size structure were measured at the St. Lucia Estuary, Mgobozeleni Estuary, Lake Sibaya and Lake Nhlange. Size structure was classified according to shell height (SH). All dissected individuals were found to be female and free from trematode infection. Salinity, water depth, temperature, and pH were the main factors correlated with population density of gastropod communities. T. granifera often reached densities well over 1000 ind. m22, displacing indigenous gastropods and becoming a dominant component of the benthic community. T. granifera successfully invaded estuaries despite frequent exposure to high salinity and desiccation, which could together eliminate .97% of the population. The persistence of T. granifera was ensured due to its high fecundity and the environmental tolerance of large adults (20-30 mm SH) which carried an average of 158612.8 SD brooded juveniles. Repeat introductions were not essential for the success of this parthenogenetic NIS. Conclusion/Significance: There is a need for a broader study on the reproductive biology of T. granifera (including the previously overlooked ''brood pouch ecology''), which affects population dynamics and may be relevant to other parthenogenetic NIS, such as Melanoides tuberculata and Potamopyrgus antipodarum. [ABSTRACT FROM AUTHOR]

Background: Studies on the development of the nervous system and the musculature of invertebrates have become more sophisticated and numerous within the last decade and have proven to provide new insights into the evolutionary history of organisms. In order to provide new morphogenetic data on opisthobranch gastropods we investigated the neuromuscular development in the nudibranch Aeolidiella stephanieae Valdéz, 2005 using immunocytochemistry as well as F-actin labelling in conjunction with confocal laser scanning microscopy (cLSM). Results: The ontogenetic development of Aeolidiella stephanieae can be subdivided into 8 stages, each recognisable by characteristic morphological and behavioural features as well as specific characters of the nervous system and the muscular system, respectively. The larval nervous system of A. stephanieae includes an apical organ, developing central ganglia, and peripheral neurons associated with the velum, foot and posterior, visceral part of the larva. The first serotonergic and FMRFamidergic neural structures appear in the apical organ that exhibits an array of three sensory, flask-shaped and two non-sensory, round neurons, which altogether disappear prior to metamorphosis. The postmetamorphic central nervous system (CNS) becomes concentrated, and the rhinophoral ganglia develop together with the anlage of the future rhinophores whereas oral tentacle ganglia are not found. The myogenesis in A. stephanieae begins with the larval retractor muscle followed by the accessory larval retractor muscle, the velar or prototroch muscles and the pedal retractors that all together degenerate during metamorphosis, and the adult muscle complex forms de novo. Conclusions: Aeolidiella stephanieae comprises features of the larval and postmetamorphic nervous as well as muscular system that represent the ground plan of the Mollusca or even the Trochozoa (e. g. presence of the prototrochal or velar muscle ring). On the one hand, A. stephanieae shows some features shared by all nudibranchs like the postmetamorphic condensation of the CNS, the possession of rhinophoral ganglia and the lack of oral tentacle ganglia as well as the de novo formation of the adult muscle complex. On the other hand, the structure and arrangement of the serotonergic apical organ is similar to other caenogastropod and opisthobranch gastropods supporting their sister group relationship. [ABSTRACT FROM AUTHOR]

The minute syrnolopsine gastropods endemic to Lake Tanganyika have been allied to a number of freshwater, marine and terrestrial groups as a consequence of superficial conchological similarity. Although early anatomical studies confirmed the cerithioid organization of this clade, their close relationship to other lake species was not consistently recognized. In several recent cladistic analyses based on molecular data, the higher taxonomic placement and sister group relationships of syrnolopsines have been unstable. The present analysis confirms that syrnolopsines possess a spermatophore-forming organ – a synapomorphy of the Paludomidae – corroborating their placement in this family. Consistent with the molecular data, syrnolopsine monophyly is supported by two characters that occur exclusively in this group (salivary gland ducts that bypass the nerve ring and a linear albumen gland). Several characters in Martelia tanganyicensis– the most diminutive syrnolopsine – are only evident in the smallest lake species thus far investigated ( Bridouxia, Stormsia) namely reduction of ctenidial leaflets, sorting area, intestine length and number of statoconia. These features are interpreted as being correlated with reduction in size. Nevertheless, close examination reveals differences in detail that allow more refined hypotheses of homology and are consistent with their independent origin. [ABSTRACT FROM AUTHOR]

The article offers information on the gastropod Hexaplex trunculus' growth. It notes that shell height development depicts two phases of growth. It mentions that the first phase was fast with an exponential growth which lasts from hatching to five months. It adds that the second phase was described as a slow logarithmic growth lasting for 13 months. Moreover, it states that the development of the average total weight exhibited three growth phases. The first phase was described as a fast growth, in the second phase the growth is low and the third phase was depicted as the most important weight increase.

Abstract: Pontohedyle milaschewitchii (Kowalevsky, 1901) is one of the most common mesopsammic opisthobranchs in the Mediterranean and Black Seas and has been considered as a comparably well-described acochlidian species. However, data on its complex internal anatomy were fragmentary and little detailed due to inadequate methodology available, and contradictory between different sources. The present study redescribes all major organ systems of P. milaschewitchii in full detail by three-dimensional reconstruction from serial semithin sections using AMIRA software. The prepharyngeal central nervous system (cns) of P. milaschewitchii is highly concentrated and shows a euthyneurous and epiathroid condition. Contrary to earlier reports, the cerebral and pleural ganglia are not fused. Aggregations of precerebral accessory ganglia can be grouped into three complexes supplied by distinct cerebral nerves. Rhinophoral ganglia with thin, double cerebro-rhinophoral connectives are described for the first time in acochlidians. A Hancock''s organ is present in the form of a conspicuous, curved fold in the epidermis posterior to the oral tentacles. Cerebral nervous features and sensory structures are discussed comparatively. Our study confirms P. milaschewitchii as having the male genital opening in an unusual position above the mouth. Homology of the ciliated vas deferens of the gonochoristic and aphallic P. milaschewitchii with that of hermaphroditic acochlidian species with cephalic male genitals is discussed. The radula formula of P. milaschewitchii is 41–54×1-1-1, i.e. the single lateral teeth are broad and, contrary to previous descriptions, undivided. SEM examination of the body wall of entire specimens revealed a special and constant ciliary pattern. Providing a novel additional set of characters for taxonomic and phylogenetic purposes, external SEM examination is suggested as the standard method for describing acochlidian species in the future. [Copyright &y& Elsevier]

Skin and stomach epithelia of the four suborders of nudibranch gastropods (Mollusca, Opisthobranchia) are characterized by large intracellular ovoid disks, here called spindles. These spindles are an evolutionary novelty in the nudibranchs; in shell-less sacoglossan species they are missing. We here examined whether the distribution and occurrence of the spindles is consistent with the assumption of a protective role against discharging nematocysts of co-habiting and prey Cnidaria. Spindles were abundant in epidermal cells of regions exposed to nematocysts, such as the cerata, the lips, the edges of lamellate rhinophores, the surfaces of non-retractile gill-like organs, as well as in the stomach epithelium of eolid and dendronotacean species which feed on Cnidaria. While cells packed with spindles almost exclusively formed the epidermis of eolid and arminacean species, they were less numerous in the skin of dendronotacean and dorid species, where glandular cells predominated. The preponderance of either glandular or spindle cells suggests a dual complementary defense strategy, on the one side the production of mucus coats and aversive glandular secretions, on the other structural defensive devices that are cushion-like entities filled with inert grains. [ABSTRACT FROM AUTHOR]

Endocrine disruption in marine populations is a growing concern. One of the best documented examples is imposex, the development of male characteristics in female gastropods, including the development of a penis and/or vas deferens, by exposure to organotins, mainly tributyltin. This syndrome has been an effective and widely used biomarker of organic tin contamination for almost 20 years. However, established imposex evaluation protocols sacrifice all the animals and repeated assessments can result in depletion of populations. To preserve animal lives as much as possible and to have a fast screening of areas subjected to organotin impacts, a non-destructive approach was tested. This approach uses reversible narcotization and a statistical criterion to evaluate the extent of imposex in the populations, instead of imposex indexes, which are based on evaluation of sacrificed, fixed animals. The data consist of two categories: males plus masculinized females in one category and normal females in another. The probability is then calculated that this sample could have been drawn from a normal population. This new method was tested in two contrasting areas of Brazil and with two different species, and the results compared to the conventional evaluation. Narcotization was completely reversed with a survival rate of 98%. Impacted sites could be identified with this technique in the same way as with the conventional one. The only limitation was that female sterility could not be verified. This disadvantage could well be compensated by the minimal mortality in the studied populations. [Copyright &y& Elsevier]

Morphological classification of snail shells is sometimes arbitrary and misleading in correct species delimitation. This topic is investigated in four nominal species of the minute gastropods of the genus Vallonia (V. pulchella, V. excentrica, V. costata and V. enniensis). First, individuals are classified according to their shell morphology. Second, variation in ribosomal internal transcribed spacer 1 DNA (ITS-1 rDNA) is analysed. Using a cladistic approach, the nucleotide positions of the ITS-1 are elucidated on apomorphic and plesiomorphic character states (outgroup=Acanthinula aculeata; Valloniidae). The molecular data yield evidence that the morphospecies V. excentrica is a paraphyletic group, comprising just a loose arrangement of individuals with similar shells. Data on fossil shells and putative divergence time are also elucidated. In the monograph on Vallonia it has been suggested that the split between the branch of V. costata and the branch of V. pulchella, V. excentrica and V. enniensis could have been in the upper Cretaceous. Based on the ITS-1 sequence alignment and the number of variable nucleotide positions, it is suggested that the last common ancestor of both branches lived at some time during the Miocene or even the Pliocene. Therefore, the fossil stem lines of Vallonia should be newly interpreted. [ABSTRACT FROM AUTHOR]

Presents abstracts of several studies presented at the 39th meeting of the Zoological Society of Israel held at the Tel Aviv University on December 1, 2002. "Variation in Aggregation Behavior and Anatomy Resulting From Differences in Degree of Sperm Competition in Groupers (Epinephelinae, Serranidae)," by A. Aronov and M. Goren; "Establishment of the Lessepsian Migrant Cellana Rota (Gastropoda) in the Mediterranean Sea and Its Demographic Effects on the Local Species Patella Caerulea," by I. Atad, T. Feldstein, A. Abelson and O. Mokady; "Unique Expression of the sPer1 Gene in Nocturnal Blind Subterranean Mole Rats," by A. Avivi, H. Oster, A. Joel, U. Albrecht and E. Nevo.

The recently proposed subclass Euomphalomorpha Bandel and Frýda, 1998 was primarily based on an openly coiled, planispiral initial whorl. Here, the protoconch of Carboniferous euomphalids is described and figured in detail previously unknown. This protoconch comprises distinctly less than one planispiral whorl with an abrupt transition to the telecoconch. It is umbilicate or openly coiled. Umbilicate or bilaterally symmetrical protoconchs are still present in Recent species of the Cocculiniformia, the Neomphalidae and the Docoglossa. A previously suggested close phylogenetic relationship between the euomphalids and primitive gastropod limpets is therefore corroborated by the protoconch morphology. The fact that several Palaeozoic gastropods, unlike most modern gastropods, have an openly coiled initial whorl is highly remarkable, but the meaning of this feature for the phylogeny and the systematics of the Gastropoda is not yet clear. [ABSTRACT FROM AUTHOR]

The ectoparasitic snail Sayella laevigata was first described by Orbigny (1842) and first placed in the genus Sayella by Odé (1994) without discussion. This study provides justification for this assignment to the genus Sayella Dall, 1885 and to the subfamily Sayellinae Wise, 1996. Sayella laevigata possesses an elongate penis, with subapical swelling tapering to a short terminal nipple, that is characteristic of the genus. [ABSTRACT FROM PUBLISHER]

The development and morphology of the pallial and pulmonary cavities of various gastropods has been investigated using epoxy-resin serial sections. In the veliger larvae of Cellana sandwicensis (Patellogastro-poda), Gibbula adansonii (Vetigastropoda), Modulus tectum (Caenogastropoda) and Ovatella myosotis (Pulmonata) the formation of the pallial cavity is nearly identical. After shell formation a shallow dorsal pallial groove develops beneath the mantle edge. During the late veliger stage, the ectoderm forms a deep invagination along the bottom of the pallial groove on the right side of the larva, giving rise to the pallial cavity. In the ellobiid O. myosotis the pallial cavity becomes the lung (=pulmonary cavity), without any major post-metamorphic modification. Thus, the lung of this species is clearly homologous with the pallial cavity of prosobranchs. The lung of pulmonates with veliger development, as well as of fresh water basommatophorans and stylommatophorans, can be shown to be homologous by comparison of adult morphology. In contrast to previous views, the pulmonate lung should be regarded as truly homologous with the pallial cavity of prosobranchs and opisthobranchs. In the onchidiid pulmonate Onchidium cf. branchiferum, the larval pallial cavity shifts posteriorly after metamorphosis, where it gives rise to a lung and a cloaca. Contrary to previous interpretations, it can be shown that the onchidiid lung is homologous with at least part of the pallial cavity. Smeagol climoi has only a small pallial cavity and no separate lung. The previously described ‘lung’ is shown to be a gland. The re-evaluation of the development and morphology of the pulmonate lung has important systematic implications: (1) The pulmonary cavity does not represent a synapomorphic character of pulmonates. (2) The gymnomorphs cannot be separated from the remaining pulmonates based on lung development. (3) The lack of a lung in the smeagolids might give reason to reconsider this group's systematic placement within the pulmonates. [ABSTRACT FROM AUTHOR]

Examines life associations of shell and operculum of Maclurites Le Sueur, 1818 from the Middle Ordovician era in Alaska. Suitability of operculum in the aperture of the shell; Illustration of Maclurites bigsbyi operculum from the Middle Ordovician of Wisconsin; Distinctions between M. bigsbyi and Maclurina logani.