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The camaenid land snail genus Camaena is widely distributed throughout Southeast Asia. Thirteen species are found in China alone. Among these, C. cicatricosa (Müller, 1774) is the most widely distributed species, including four subspecies, C. c. ducalis (Ancey, 1885), C. c. inflata (Möllendorff, 1885), C. c. obtecta (Fischer, 1898) and C. c. connectens (Dautzenberg & Fischer, 1906). The systematics of these taxa is revised herein based on comparative shell morphology and anatomy as well as analyses of DNA sequences of two mitochondrial genes (COI, 16S rRNA) and one nuclear marker, ITS2. We found that all subspecies form well-supported clades in a molecular phylogeny and are well-differentiated from each other by genetic distances that are consistent with amounts of interspecific differentiation. In addition, they clearly differ from each other in reproductive features. Based on these observations, we elevate all four subspecies to the rank of full species. Moreover, based on morphological and mitochdondrial differentiation, we describe a new species, Camaena poyuensis sp. n. from Guangxi, China. The new species conspicuously differs from its sibling species C. cicatricosa in having a larger and more depressed shell, a completely covered umbilicus, more or less purplish peristome, an obtuse angle at the junction of the basal and columellar lip, longer pedunculus of the bursa copulatrix, thicker epiphallus and penis, and short conic verge. Previous named species are also redescribed on their shell and anatomical characters, because the original descriptions are uninformative. [ABSTRACT FROM AUTHOR]

Hermissenda crassicornis is a model organism used in various fields of research including neurology, ecology, pharmacology, and toxicology. In order to investigate the systematics of this species and the presence of cryptic species in H. crassicornis, we conducted a comprehensive molecular and morphological analysis of this species covering its entire range across the North Pacific Ocean. We determined that H. crassicornis constitutes a species complex of three distinct species. The name Hermissensa crassicornis is retained for the northeast Pacific species, occurring from Alaska to Northern California. The name H. opalescens is reinstated for a species occurring from the Sea of Cortez to Northern California. Finally, the name H. emurai is maintained for the northwestern species, found in Japan and in the Russian Far East. These three species have consistent morphological and color pattern differences that can be used for identification in the field. [ABSTRACT FROM AUTHOR]

Bothriembryon sophiarum sp. n. is described, based on shell and anatomical morphology, from the coastal area of south-easternmost Western Australia. This is the first description of a new extant Australian bothriembryontid in 33 years. The shell of B. sophiarum is slender with a unique teleoconch sculpture. It is found in low coastal scrub on cliff edges and escarpments and because of its restricted distribution, qualifies as a short range endemic. [ABSTRACT FROM AUTHOR]

The aims of the study were (i) to reveal the pattern of phylogeny of Pseudamnicola inhabiting the Aegean Islands, (ii) to describe and analyse the variation of the morphology in 17 populations of Pseudamnicola from the springs on the Aegean Islands not studied so far and considering also another seven populations studied earlier and (iii) to find out which model is more applicable to the island Pseudamnicola populations: either a model in which a relict fauna rich in endemics is differentiated in a way that mainly reflects the geological history of the area or a model in which a relatively young fauna is composed of more or less widely distributed taxa, with relatively high levels of gene flow among the springs they inhabit. To address the above issues, the morphology and the mitochondrial genes-cytochrome oxidase subunit I (COI) and ribosomal 16S-and nuclear genes-ribosomal 18S, 28S and histone 3 (H3)-were analysed. COI and COI+16S rRNA+18S datasets gave trees with identical topology in both ML and Bayesian inference. The 24 studied populations of Pseudamnicola form 16 clades, each of them generally having low levels of intrapopulation genetic differentiation. The generalised mixed Yule coalescent (GMYC) procedure and the Automatic Barcode Gap Discovery (ABGD) analysis for COI identified 16 Pseudamnicola entities coinciding with clades of the ML tree based on 44 haplotypes and 189 sequences. The present pattern of diversity, together with dating of divergence time, reflects a short story of colonisation/recolonisation, supported by the Late Pleistocene land bridges, rather than the consequences of earlier geological events. The principal component analysis (PCA) on the shells of the molecularly distinct clades showed differences, although variability ranges often overlap. Female reproductive organs showed no differences between the clades, and penile characters differed only in some cases. [ABSTRACT FROM AUTHOR]

The rock-dwelling land snail Pyramidula pusilla was analysed genetically and morphologically with an emphasis on its eastern Alpine distributional area. Genetic variation and phylogeographic patterns were inferred by mitochondrial cytochrome c oxidase subunit 1 gene sequences (650 bp), while shell variability was investigated by shell measurements and landmark analyses. The phylogenetic analyses revealed two clades in Austria (clades 3 and 4), of which one also contained individuals from Turkey. Other samples originating from the Balkan region (Albania, Greece) and Turkey were well separated in the tree, forming two distinct sister clades (clades 1 and 2). Concerning clades 3 and 4 there is no clear geographical pattern and both clades cooccur at several (11) sites; the same is true for clades 1 and 2. There are also morphological differences between clades: clades 1 and 2 differ from the other clades in size as well as shape, whereas clade 3 differs from clade 4 only in size. Considering all results combined, they imply that the samples analysed might actually represent more than one species and that, contrary to former assumptions, two species of Pyramidula may occur within the eastern Alps. However, comprehensive taxonomic conclusions cannot yet be drawn, for reasons connected with insufficiently justified species assignment: (1) high morphological variation within clades, (2) lack of clear diagnostic information in original descriptions, causing a lack of reliable distributional data and (3) lack of data over the whole distributional range of the genus. Analyses of ncDNA (e.g. microsatellites) to quantify the extent of gene flow, as well as breeding experiments between different clades, could help to clarify the delimitation of species. Despite these taxonomic uncertainties, the results provide insights on Pyramidula within the eastern Alpine region, suggesting that it survived the Pleistocene oscillations without dramatic bottlenecks and is capable of fast expansion to (re)populate formerly glaciated areas. [ABSTRACT FROM AUTHOR]

Pseudamnicola pieperi, previously known only from Karpathos Island (southeast Aegean Sea), is reported from seven new localities on Karpathos and redescribed and taxonomically circumscribed using morphological, anatomical and mtDNA sequence data. Additionally, two new species of Pseudamnicola are described from Rodos, i.e. P. ianthe and P. ilione. The species from Karpathos and Rodos are differentiated from each other (and from the other Greek and circum Mediterannean congeners having similarly shaped shells and penes) by details of the radula, the nervous system and the female genitalia; they are also genetically divergent relative to those congeners that have been sequenced (mtCOI divergence: 3.6-13.5%). [ABSTRACT FROM AUTHOR]

This contribution provides the first integrative revision of the Siphonaria species described and reported from southern South America, by combining information on shell morphology, distal portion of the genital system, radula, molecular data and living animal. More than 200 lots, from all along the Uruguayan, Argentinean and southern Chilean coasts, including the Malvinas (Falkland) Islands and South Georgia, were studied. Among the nine nominal species listed for this area, only the presence of Siphonaria lessonii Blainville, 1827 and S. lateralis Gould, 1846 could be confirmed. The intraspecific variability of these two species along their distributional ranges is examined. Siphonaria magellanica Philippi, 1855 and S. antarctica Gould, 1852 are regarded as probable synonyms of S. lessonii. The Magellanic records of S. tristensis are reassigned to S. lessonii and those of S. macgillivrayi to S. fuegiensis n. sp. The similarity of S. redimiculum Reeve, 1856, S. laeviuscula Sowerby, 1835 and S. lineolata Sowerby, 1835 to the three species confirmed in the studied area is discussed. The Chilean S. laevis Philippi, 1846 is considered a nomen dubium. All available types are figured and a lectotype is designated for S. redimiculum. [ABSTRACT FROM AUTHOR]

The validity of morphology-based species boundaries between the southern African representatives of the genus Tricolia Risso, 1826 was assessed using mitochondrial COI and 16S rRNA sequence data. Most phylogenies obtained from individual and combined genetic datasets recovered 10 of the southern African members of the genus as a monophyletic clade. No COI sequences of the 11th species (T. adusta) were available, but this species clustered among the other African species in the 16S rRNA phylogeny. Discrepancies between morphology and genetics were identified in two clades within which there was limited genetic variation and no differentiation between two groups of nominal species, comprising respectively T. africana (Bartsch, 1915) and T. capensis (Dunker, 1846), and T. bicarinata (Dunker, 1846), T. insignis (Turton, 1932) and T. kraussi (Smith, 1911). In both cases the distributions of the nominal taxa coincide with well-known biogeographic disjunctions, and there is evidence of overlapping and intergrading shell characters. We propose that both of these unresolved clades be recognized as single, phenotypically plastic species, for which the oldest available names are respectively T. capensis and T. bicarinata. Despite the resultant reduction in number of recognized species, the phasianellid fauna of southern Africa remains the most diverse in the world, with 10 endemic species and 3 tropical species extending south into KwaZulu-Natal. [ABSTRACT FROM AUTHOR]

The Roman snail Helix pomatia Linnaeus, 1758 is a large terrestrial gastropod very common in central and southeastern Europe, and is the type species of the genus. A recent molecular phylogenetic study has uncovered two divergent lineages within the species as currently conceived. One represents the true H. pomatia, the second corresponds to a previously recognized subspecies H. pomatia thessalica Boettger, 1886. Using more samples, new molecular data and thorough morphological investigations, we redescribe the latter as a separate species. Morphological differences, especially colouration and surface sculpture of the shell and dark colouration of distal genitalia, distinguish this taxon reliably from H. pomatia. The species is widespread in the southern Balkans, but its range extends also to central Europe along the Carpathian Arc. Thus, its distribution broadly overlaps with that of H. pomatia and we have found evidence for occasional hybridization between the two species. Some lineages of H. thessalica seem to be restricted to the Carpathians and their vicinity; these might have survived locally during the last glacial. By clarifying the taxonomy of H. pomatia, we make the crucial first step towards elucidating the phylogeographic history of this iconic member of the European land snail fauna. [ABSTRACT FROM AUTHOR]

Several land-snail species of the helicoid and limacoid superfamilies possess one or more love-darts, which seem to have evolved as a result of conflict over the fate of donated sperm and/or as a way to select the most fit sperm donor. A love-dart is a calcareous stylet used during mating encounters to pierce the partner's body wall. When used, it carries accessory gland mucous products that influence the partner's physiology. Most of the knowledge on the effects of the glands' mucus derives from a single well-studied species, Cornu aspersum, in which the mucus increases the male reproductive success of the dart user. However, detailed descriptions on the use of the dart are limited to just a few other species. Hence, here we compare physiological, morphological and behavioural aspects concerning love-darts in several dart-bearing species. Patterns in the use of the dart are identified according to family and we discuss the coevolution of the morphology of the dart and anatomical traits of the reproductive system. The reported physiological effects caused by the dart's mucus suggest a common function of the dart in increasing male reproductive success. Nevertheless, caution is needed when generalizing the use and effects of the love-dart, which are predominantly based on one model organism. [ABSTRACT FROM AUTHOR]

Pseudosuccinea columellaandRadix natalensislive in the same habitat in Egypt and are important intermediate hosts ofFasciola hepaticaandF. gigantica. Our study aimed to characterise both snail species using molecular analysis and shell measurements. The ranges of morphometric parameters overlapped in the two lymnaeids, indicating that they do not clearly differentiate the two species. PCR-sequence analysis of the nuclear ribosomal small subunit rRNA and the polymorphic mitochondrial cytochrome oxidase subunit 1 (CO1) genes were used to determine the genetic identity and the potential diversity of the snails. Little intrasequence variations were detected in the sequences of both gene loci, indicating the potential homogeneity of lymnaeid populations in Egypt. Generated sequences of the mitochondrial CO1 gene locus forR. natalensisshowed obvious heterogeneity compared to other sequences in GenBank. Molecular characterisation of these lymnaeids might help to understand the snails’ biodiversity in a bid to control these populations and their related diseases. [ABSTRACT FROM AUTHOR]

Tonnoideans are marine carnivorous caenogastropods that prey on different invertebrates, namely polychaetes, sipunculids, bivalve and gastropod molluscs, and echinoderms. The morphology of the digestive system of 20 species from five families of the Tonnoidea was examined (for most of these species for the first time), and the salivary glands of six of them were studied using serial histological sections. Most of the studied families are rather similar anatomically, except Personidae (Distorsio), which differs both in proboscis morphology and the structure of the salivary glands. In most tonnoideans the salivary glands are split morphologically and functionally into anterior and posterior lobes, the latter synthesising strong sulfuric acid. The ducts of the posterior lobes are lined with non-ciliated epithelium and receive usually paired ciliated ducts from the anterior lobes to form a non-ciliated common duct, opening into the buccal cavity. In Personidae, the salivary glands are not separated into lobes, but are instead composed of ramifying tubules that are histologically different in the proximal and distal parts. Radulae of Tonnoidea are rather variable, with different patterns of interlocking teeth, both in the transverse and longitudinal rows, which may be related to particular feeding mechanisms. Due to the peculiarities of Personidae, the close relationship between that family and the rest of the Tonnoidea is questioned. [ABSTRACT FROM AUTHOR]

Post-mortem drift is a common phenomenon within living shelled cephalopods (Nautilidae,Sepiidae and Spirulidae) and has led to the misinterpretation of geographical ranges in some species. In this study, the distributional ranges of reliably identified cuttlefish and beach-collected sepions (cuttlebones) from the Australian Museum, Museum Victoria and the Museum and Art Gallery of the Northern Territory collections were compared to determine the extent of sepion drift. In 12 of the 24 species examined, the distributions of dry sepions extended beyond the currently known ranges of the living populations as ascertained from the collection of intact animals. In some cases, this was in the order of hundreds of kilometres. These discrepancies are discussed in relation to the known depth ranges of each species, sepion morphology and oceanography. The results suggest that a cautionary approach should be taken in interpreting distributional data, particularly when using electronic databases that are likely to comprise sepion and whole animal locality information. Sepion distributions alone may be indicative of drift outside the true range of a species, or may suggest wider distributions of cuttlefish populations than are currently understood based on available information. Sepion drift is postulated to be the more likely explanation. [ABSTRACT FROM AUTHOR]

Despite the commercial aquaculture importance of the Greenshell™ mussel, Perna canaliculus , the morphological development of gill structure (ctenidial filaments) in relation to potential particle feeding abilities have not been described. Scanning electron microscopy (SEM) and light microscopy were used to examine the ontogenetic changes across five size classes of mussels from post-settlement larvae to adults ranging from 300 μm to > 100 mm in shell height. Key morphological characteristics were measured including filament width, the eulatero-frontal cirri (ELF) length, interfilamentary space (IFS) and the mean distance between adjacent ELF, d ELF . Overall the development of the ctenidial filaments in P. canaliculus , shared some similarities to other homorhabdic filibranch bivalves with differences in the timing of development. Filament width and ELF length followed sigmoidal growth curves in relation to increasing shell height of mussels. The morphological changes of the ctenidia, reflected in changes in the ELF/IFS ratios, together with the development of cilia in the ELF may help explain the differences in the capture efficiency of small particles between small individuals (< 6 mm in shell height) and bigger mussels (around 60 mm in shell height). Ctenidial filaments in small individuals are not fully developed and resemble the “leaking” model, letting small particles through and capturing particles between 15–25 μm, while the filaments in bigger mussels resemble the “complete block” model being able to capture bacteria-sized particles around 2 μm. This information is not only useful to further the understanding of the feeding biology of this species, but also for the feeding management in hatcheries producing large numbers of juveniles of this commercially important species, considering that under current hatchery practices small-sized mussels are being fed microalgal species mainly with a size of around 5 μm. Statement of relevance –This article provides information regarding the gill ontogenetic development of the commercially important Greenshell™ mussel, Perna canaliculus . –The information given will help improve hatchery practices, especially regarding the selection of adequate particle size for feeding post-settlement P. canaliculus . –Considering that mussel aquaculture is a global phenomenon, these results could be used worldwide in order to help the industry find economically feasible alternatives for mussel juvenile supply. The New Zealand Greenshell™ industry has recently invested $20 M to build a large scale hatchery/nursery to address an on-going shortage with seed supply which has been constraining the growth of the industry. Shortages of mussel seed, caused by poor feeding and starvation, have resulted in seed shortages in the industry for the last three years, shaving off almost 20% production of the entire industry, in the order of $30 M lost production a year. Hence there is intense interest in better understanding the feeding biology of juvenile mussels and using this knowledge to resolve the major production issues faced by this aquaculture industry. From our international contacts, we understand that other countries with significant mussel farming industries face similar issues, such as Chile. Therefore, we believe that there is strong reader interest and value in the publication of this fundamental research. [ABSTRACT FROM AUTHOR]

The genus Nata Watson, 1934 is a southern African endemic belonging to the Gondwanan family of carnivorous snails, Rhytididae. We present a molecular phylogeny of the genus based on two mitochondrial (16S and COI) and two nuclear genes (ITS2 and 28S RNA), and complement this with an appraisal of morphological characters relating to both the shell and soft parts. We identify four reciprocally monophyletic lineages for which valid names are already available, plus two undescribed species restricted to the Albany Thicket Biome. We show that Nata sensu lato may not be monophyletic. Rather there exist two deep lineages within Nata s.l. , one lineage potentially sister to a clade dominated by the Australian and New Zealand radiation, and the other occupying a basal position within Rhytididae. Accordingly we recommend a revision recognising two genera, namely Nata s.s. and Natella respectively. Despite deep molecular divergences within Nata s.s. , phenotypic evolution has been remarkably conserved, and contrasts greatly with that exhibited across other major lineages within the Rhytididae. [ABSTRACT FROM AUTHOR]

To explore the feasibility of using beak microstructure to estimate the age of oceanic squid, sagittal sections in the upper beak were used to validate the age of the red flying squid (Ommastrephes bartramii) in the North Pacific Ocean. The growth rates of mantle length (ML) and body weight (BW) were estimated on the basis of beak increments. We compared growth curves derived from previous statolith-based studies and those from this study. Results indicate that the mean age of females and males was 203 d (standard deviation [SD] 55) and 180 d (SD 45). The hatching period occurred during October-June of the following year, and hatching peaked during January-April on the basis of back-calculation. All sampled squid belonged to the winter-spring cohort. Females and males had a similar growth pattern in ML and BW with increased ages, except for male ML after age 301-350 d. An exponential model best described the relationships between age and ML as well as BW for both sexes. The difference in growth curves and lower growth rates reported here, compared with those of previous studies, may result from different stock structures and extreme weather. This study confirmed that beak length works well for estimating the age of oceanic squid. [ABSTRACT FROM AUTHOR]

In this study, we describe the microstructure and ultrastructure of the epipodial papillae and epipodial tentacles of Haliotis tuberculata using light and electron microscopy. The epipodial papillae vary morphologically; they are subdivided into several subpapillae whose surface is covered by small micropapillae. The epipodial tentacles are large extendable conically elongated structures whose surface is differentiated in two regions: the dorsal region with long corrugated folds, and a ventral region composed of three parts, a basal part with the same structure as the dorsal, a middle part with shorter corrugated folds and an apical part with large micropapillae. Although the thin sections and ultrastructure examination show that the epithelium of both organs is morphologically similar and composed of supporting cells, sensory cells and different types of secretory cells, there is a certain specialization in their secretory product. Although the epithelium of both structures was positive for acidic glycoconjugates, the tentacle epithelium was also positive for neutral sugars. Further specific differences were revealed by lectin histochemistry. Because papillae and tentacles can be extended or retracted depending on environmental conditions, they probably have tactile and olfactory functions. [ABSTRACT FROM AUTHOR]

Pronounced mitochondrial heterogeneity within putative species of Pleuroceridae has prevented meaningful systematic revisions of this critically imperilled freshwater family. Previous studies have demonstrated that this mitochondrial diversity often produces polyphyletic species on mitochondrial gene trees, but its significance is unclear. Hypotheses advanced to explain this pattern have included cryptic species, retained ancestral polymorphisms and introgression; other possible explanations such as doubly uniparental inheritance or the presence of pseudogenes have not been given due consideration. Previous analyses have not included adequate sampling, neither in terms of number of individuals nor in geographic coverage, to adequately test any of these hypotheses. To fully characterize mitochondrial heterogeneity in pleurocerids and robustly assess possible causal explanations, we collected 239 individuals representing four putative species from seven sites and sequenced the COI and 16S rRNA mitochondrial genes and the H3 nuclear gene for all individuals. We also used whole-genome shotgun sequencing to construct and annotate a mitochondrial genome for one individual. Characters with demonstrated utility in morphospecies delineation of gastropods (head-foot coloration, shell and radular morphology, pallial oviduct anatomy) were examined for a subset of individuals to determine whether morphology co-varied by haplotype clade. We found pronounced mitochondrial heterogeneity at both the population level and species level in three of the species examined, but our data reject paralogous nuclear copies of mitochondrial genes (NUMTs) and doubly uniparental inheritance as causal mechanisms, and there was no evidence of cryptic diversity. Mutation rates were found to differ significantly among mitochondrial lineages, and population genetic statistics revealed a signature of balancing selection that could be acting to maintain this diversity. The observed pattern is similar to that seen in lineages with inherited endosymbionts like Wolbachia infections, which merits further investigation. Although questions remain concerning the precise cause(s) of intraspecific mitochondrial diversity in pleurocerids, nuclear and/or genomic data, combined with anatomical and life history investigations in an integrative phylogenetic context, is the most promising avenue for resolving pleurocerid systematics. [ABSTRACT FROM AUTHOR]

The taxonomic significance of the morphological variability present in the genus Ptychomya Agassiz has remained obscure due to inadequacy of the traditional qualitative approach to account for complex patterns of variation. In this work, we focus on solving the distinction between intra- and interspecific variability in Ptychomya from Hauterivian marine beds of the Neuquen Basin (west-central Argentina), a longstanding and unresolved palaeontological issue, using the quantitative framework provided by geometric morphometrics and multivariate statistics. The species Ptychomya koeneni Behrendsen and several subspecies had been recognized in the studied succession by former authors based on qualitative morphological descriptions. We tested two hypotheses: (1) that there exist morphological discontinuities between hypothesized species that mark their boundaries; and (2) that morphology follows a pattern of geographical variation, suitable for recognition of subspecies. We find two morphological groups in the studied sample, with a significant morphological gap between them, supporting the idea that there are at least two species in the studied succession, Ptychomya cf. koeneni and Ptychomya coihuicoensis Weaver. On the other hand, we found no correspondence between morphological and geographical distributions, leading to the conclusion that the named subspecies are invalid taxa. This study highlights the potential of this methodological approach for solving the taxonomy of this notorious genus of pandemic distribution during the Cretaceous. [ABSTRACT FROM AUTHOR]

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A new giant clam species, Tridacna ningaloo Penny & Willan, 2014 has been described from Ningaloo Reef, Western Australia. Meanwhile, it has been suggested that Noah's giant clam, Tridacna noae (Röding, 1798), previously resurrected from synonymy with T. maxima (Röding, 1798), is an invalid name. We assessed the validity of resurrecting T. noae and designating a neotype for it, against the rules of zoological nomenclature and found no flaw in these acts. We then compared the genetic and morphological characters used in the respective diagnoses of T. noae and the newly-described Tridacna ningaloo. No difference was apparent between T. ningaloo and T. noae except, possibly, in mantle ornamentation patterns. In particular, the holotype of T. ningaloo possesses a mitochondrial DNA haplotype identical to T. noae. Thus, the hypothesis that T. ningaloo is a species distinct from T. noae was not supported by clear morphological evidence and it was contradicted by the available genetic evidence. Tridacna ningaloo should be regarded as a junior synonym of T. noae. [ABSTRACT FROM AUTHOR]

Polyplacophoran molluscs show low morphological diversity compared to other marine invertebrate clades, yet chitons are ecologically important grazers that occupy a range of distinct ecological niches. We investigated a potential functional correlate of niche separation in three species of co-occurring mopallid chitons that have total ranges across differing environments ( Mopalia muscosa, Mopalia lignosa, Katharina tunicata). We found that the force needed to fracture the protective valves varied significantly among species. K. tunicata, whose valves have a relatively reduced exposed dorsal surface, was significantly more resistant to fracture than the two Mopalia species (mean force: K. tunicata = 31.9 ± 4.5 N; M. lignosa = 12.5 ± 0.8 N; M. muscosa = 20.2 ± 0.8 N). In Mopalia spp., the terminal valves were significantly stronger than intermediate valves (i.e. higher force to fracture), whereas all valves in K. tunicata appeared to be functionally equivalent. To assess whether future chemical changes predicted under ocean acidification (OA) will affect these species differently, we measured the force to fracture of valves after 10 days of exposure to elevated pCO (control = 8.0 pH [407 ± 104, pCO], elevated = 7.5 pH [1544 ± 249, pCO]) for both live animals and dissected individual valves. Although previous experimental OA work found significant impacts of elevated pCO on adult mollusc shells over similar timescales, we saw no reduction in total strength related to treatment. Our data demonstrate that diversity in chiton valve morphology has functional implications and that physical changes in local topology and wave exposure may have stronger impacts on adult chitons than changes in ocean chemistry under future climate change. [ABSTRACT FROM AUTHOR]

Background: Mollusks represent the largest lophotrochozoan phylum and exhibit highly diverse body plans. Previous studies have demonstrated that transcription factors such as Pax genes play important roles during their development. Accordingly, in ecdysozoan and vertebrate model organisms, orthologs of Pax2/5/8 are among others involved in the formation of the midbrain/hindbrain boundary, the auditory/geosensory organ systems, and the excretory system. Methods: Pax2/5/8 expression was investigated by in situ hybridization during the development of representatives of the two major molluscan subclades, Aculifera and Conchifera. Results: Compared to the investigated polyplacophoran and bivalve species that lack larval statocysts as geosensory organs and elaborate central nervous systems (CNS), cephalopods possess highly centralized brains and statocysts. Pax2/5/8 is expressed in regions where sensory cells develop subsequently during ontogenesis. Expression domains include esthetes and the ampullary system in polyplacophorans as well as the eyes of cephalopods. No Pax2/5/8 expression was observed in the less centralized CNS of bivalve, polyplacophoran, and gastropod embryos, thus arguing for a loss of Pax2/5/8 involvement in CNS development in these lineages. In contrast, Pax2/5/8 is expressed among others in brain lobes along the trajectory of the esophagus that divides the cephalopod brain. Conclusions: Our results, along with those on Otx- and Hox-gene expression, demonstrate that the cephalopod condition is similar to that in mouse and fruit fly, with Otx being expressed in the anterior-most brain region (except for the vertical lobe) and a Pax2/5/8 expression domain separating the Otx-domain from a Hox-gene expressing posterior brain region. Thus, Pax2/5/8 appears to have been recruited independently into regionalization of non-homologous complex brains of organisms as different as squid, fruit fly, and mouse. In addition, Pax2/5/8 is expressed in multimodal sensory systems in mollusks such as the esthetes and the ampullary system of polyplacophorans as well as the eyes of cephalopods. Pax2/5/8-expressing cells are present in regions where the future sensory cells such as the polyplacophoran esthetes are situated and hence Pax2/5/8 expression probably predates sensory cell development during ontogeny. In mollusks, Pax2/5/8 is only expressed in derivatives of the ectoderm and hence an ancestral role in molluscan ectoderm differentiation is inferred. [ABSTRACT FROM AUTHOR]

With about 800 Recent species, 'miters' are a widely distributed group of tropical and subtropical gastropods that are most diverse in the Indo- West Pacific. They include the two families Mitridae and Costellariidae, similar in shell morphology and traditionally treated as close relatives. Some genera of deep-water Ptychatractidae and Volutomitridae are close to miters in shell morphology, and the term 'mitriform gastropods' has been introduced to refer to Mitridae, Costellariidae, and this assortment of convergent forms. The present study aimed at the reconstruction of phylogenetic relationships of mitriform gastropods based on representative taxon sampling. Four genetic markers [cytochrome c oxidase subunit I ( COI ), 16S and 12S rRNA mitochondrial genes, and H3 (Histone 3) nuclear gene] were sequenced for over 90 species in 20 genera, and the molecular data set was supplemented by studies of radula morphology. Our analysis recovered Mitridae as a monophyletic group, whereas the genus Mitra was found to be polyphyletic. Of 42 mitrid species included in the analysis, 37 formed a well-supported 'core Mitridae' consisting of four major clades, three of them consistent with the subfamilies Cylindromitrinae, Imbricariinae, and Mitrinae, and Strigatella paupercula standing out by itself. Basal to the 'core Mitridae' are four minor lineages, with the genus Charitodoron recognized as sister group to all other Mitridae. The deep-water family Pyramimitridae shows a sister relationship to the Mitridae, with high support for a Pyramimitridae + Mitridae clade. Our results recover the monophyly of the Costellariidae, which form a well-supported clade that also includes Ptychatractidae, Columbariinae, and Volutomitridae, but not Mitridae. Most derived and diverse amongst Costellariidae are species of Vexillum, characterized by a bow-shaped, multicuspidate rachidian tooth. Several previously unrecognized deep-water costellariid lineages are revealed. Their members retain some plesiomorphies - in particular a tricuspidate rachidian tooth - that makes them morphologically intermediate between ptychatractids and Vexillum. The taxa of Ptychatractidae included in the analysis are not monophyletic, but form three well-supported, unrelated groupings, corresponding respectively to Ceratoxancus + Latiromitra, Exilia, and Exiliodea. None of them shows an affinity to Pseudolividae. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

Bilaterally asymmetrical glochidia (i.e. bivalved parasitic larvae bearing a large marginal appendage on a single valve) have been reported from five Asian freshwater mussel genera belonging to two separate subfamilies, the Gonideinae (i.e. Pseudodon, Solenaia, and Physunio) and Rectidentinae (i.e. Contradens and Trapezoideus). This classification requires that the bilaterally asymmetrical glochidium-bearing mussels are not monophyletic, and suggests that this atypical larval morphology evolved twice in the same geographic region. Although homoplastic glochidium characters are known (e.g. marginal appendages and size), we hypothesized that bilaterally asymmetrical glochidia represent a novel morphological synapomorphy. We tested the monophyly of the mussels bearing bilaterally asymmetrical glochidia using a molecular matrix consisting of representatives from all six freshwater mussel families and three molecular markers ( 28S, 16S, and COI). Bayesian inference, maximum likelihood, and ancestral state reconstruction were employed to estimate the phylogeny and larval trait transformations. The reconstructed phylogeny rejects the monophyly of the asymmetrical glochidium-bearing mussels and resolves two putative origins of asymmetrical glochidia; however, ancestral state reconstruction supports asymmetrical glochidia as a synapomorphy of only one supraspecific taxon of the Rectidentinae. In the Gonideinae, asymmetrical glochidia were autapomorphic of Pseudodon cambodjensis ( Petit, 1865). That is, no other taxa resolved among the Gonideinae had bilaterally asymmetrical glochidia, including other Pseudodon species. We describe how the alleged intrageneric glochidial variation in Pseudodon, and in the other genera of the Gonideinae reported to have asymmetrical glochidia (i.e. Solenaia and Physunio), challenge the resolved convergence of asymmetrical glochidia. Our results are discussed in the context of freshwater mussel larval evolution, patterns in life-history traits, and the classification of freshwater mussels generally. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

Recently discovered hydrothermal vent fields on the East Scotia Ridge ( ESR, 56-60° S, 30° W), Southern Ocean, and the South West Indian Ridge ( SWIR, 37° S 49° E), Indian Ocean, host two closely related new species of peltospirid gastropods. Morphological and molecular (mitochondrial cytochrome c oxidase subunit I, COI) characterization justify the erection of G igantopelta gen. nov. within the Peltospiroidae with two new species, G igantopelta chessoia sp. nov. from ESR and G igantopelta aegis sp. nov. from SWIR. They attain an extremely large size for the clade Neomphalina, reaching 45.7 mm in shell diameter. The oesophageal gland of both species is markedly enlarged. Gigantopelta aegis has a thick sulphide coating on both the shell and the operculum of unknown function. The analysis of a 579-bp fragment of the COI gene resulted in 19-28% pairwise distance between Gigantopelta and six other genera in Peltospiridae, whereas the range amongst those six genera was 12-28%. The COI divergence between the two newly described species of Gigantopelta was 4.43%. Population genetics analyses using COI (370 bp) of 30 individuals of each species confirmed their genetic isolation and indicate recent rapid demographic expansion in both species. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

We morphologically analyzed 79 cephalopod specimens from the North and Baltic Seas belonging to 13 separate species. Another 29 specimens showed morphological features of either Alloteuthis mediaor Alloteuthis subulata or were found to be in between. Reliable identification features to distinguish between A. media and A. subulata are currently not available. The analysis of the DNA barcoding region of the COI gene revealed intraspecific distances (uncorrected p) ranging from 0 to 2.13 % (average 0.1 %) and interspecific distances between 3.31 and 22 % (average 15.52 %). All species formed monophyletic clusters in a neighbor-joining analysis and were supported by bootstrap values of ≥99 %. All COI haplotypes belonging to the 29 Alloteuthis specimens were grouped in one cluster. Neither COI nor 18S rDNA sequences helped to distinguish between the different Alloteuthis morphotypes. For species identification purposes, we recommend the use of COI, as it showed higher bootstrap support of species clusters and less amplification and sequencing failure compared to 18S. Our data strongly support the assumption that the genus Alloteuthis is only represented by a single species, at least in the North Sea. It remained unclear whether this species is A. subulata or A. media. All COI sequences including important metadata were uploaded to the Barcode of Life Data Systems and can be used as reference library for the molecular identification of more than 50 % of the cephalopod fauna known from the North and Baltic Seas. [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]

Twenty-five species of Pectinoidea (24 Propeamussiidae, 1 Cyclochlamydidae) are herein listed from the Mozambique Channel, northwestern and southern Madagascar, and northeastern South Africa. New species: Propeamussium rosadoi, Parvamussium catillus, Parvamussium kilburni, Parvamussium puillandrei, Parvamussium strongae, Cyclopecten cassiculus, Cyclopecten kantori, Cyclochlamys bacachorda. New synonym: Amussium sewelli Knudsen, 1967 = Propeamussium watsoni (E.A. Smith, 1885). New records for the Mozambique Channel and northwestern Madagascar: Propeamussium andamanicum, Propeamussium arabicum, Propeamussium caducum, Propeamussium jeffreysii, Propeamussium sibogai, Propeamussium watsoni, Parvamussium formosum, Parvamussium scitulum, Parvamussium torresi, Parvamussium vesiculatum, Cyclopecten kapalae, Similipecten eous. New records for southern Madagascar: Propeamussium jeffreysii, Propeamussium sibogai, Propeamussium watsoni, Parvamussium formosum, Parvamussium scitulum, Parvamussium thyrideum, Parvamussium vesiculatum, Parvamussium vidalense, Cyclopecten kapalae, Similipecten eous. New record for South Africa: Propeamussium jeffreysii, Parvamussium formosum, Parvamussium scitulum, Cyclopecten horridus, Similipecten eous. [ABSTRACT FROM AUTHOR]

The morphology and taxonomy of two new and two poorly known ciliate species of Ancistrum, found in the mantle cavity (mainly on gills) of marine molluscs from culture beds and pools along the Chinese coast of the Yellow Sea, were investigated using living observation and silver impregnation. Ancistrum haliotis n. sp. was isolated from the abalone Haliotis discus hannai Ino, A. crassum Fenchel, 1965 from the purple clam Saxidomus purpuratus (Sowerby), A. acutum n. sp. from the surf clam Mactra veneriformis Reeve, and A. japonicum Uyemura, 1937 from both the venus clam Cyclina sinensis (Gmelin) and from Dosinia japonica (Reeve). Ancistrum haliotis differs from its most similar relative A. mytili (Quennerstedt, 1867) by the body outline (anterior portion narrower vs. wider than the posterior portion), the macronuclear shape (broadly ellipsoidal vs. reniform or sausage-like), and by having fewer somatic kineties (28-32 vs. usually more than >40). Ancistrum crassum is characterized by the naked area at the apical end of the cell, the relatively short buccal field occupying about two thirds of the body length, and the posterior-dorsal cone-shaped prolongation. Ancistrum acutum n. sp. and A. japonicum are almost identical in morphometry, but differ distinctly in the live morphology (anterior end pointed and posterior end rounded vs. anterior end narrowly rounded and posterior-dorsal end protruded) and ciliary pattern (all right-side kineties extend to posterior body end vs. all rightside kineties excluding somatic kinety 1 distinctly shortened posteriad, forming a glabrous zone). We neotypify Ancistrum japonicum and discuss the taxonomic status of the four species. Based on an evaluation of all nominal species of Ancistrum and Ancistrumina, we recognize nine valid species of Ancistrum and provide a tabular guide to their identification. Fenchelia Raabe, 1970 is regarded as a junior synonym of Ancistrum Maupas, 1883. We synonymize Ancistrumina nucellae Khan, 1970 with Ancistrum japonicum Uyemura, 1937 and Ancistrum edajimanum Oishi, 1978 with A. crassum Fenchel, 1965. [ABSTRACT FROM AUTHOR]

We report for the first time the presence of Galba neotropica in Santa Fe province, Pampean Argentina. Until the present work, the identity of the intermediate host of Fasciola hepatica in this region, the most important livestock production area of Argentina, was unknown. This report extends the geographic distribution of G. neotropica and is the first to provide molecular and morphological information on this species in Argentina. During summer 2013, snails were collected on private livestock farms with high prevalence of fasciolosis in cattle. Specimens were identified by using the nuclear sequences of the internal transcribed spacers ITS-1 and ITS-2, the shell and the shape and size of the male reproductive organs. Molecularly, ITS-1 and ITS-2 nuclear sequences exhibit 100% nucleotide identity with G. neotropica from Lima, Peru. Morphologically, G. neotropica from Santa Fe province was indistinguishable from Galba viatrix and Galba cubensis, the other two cryptic species within this South American group of lymnaeids. The combination of molecular and morphological analyses is strongly recommended to identify lymnaeids at species level. The identity of the intermediate host and the subsequent knowledge of its susceptibility, behaviour, distribution, ecology and biology are important components in developing effective measures to control fasciolosis. [ABSTRACT FROM AUTHOR]

The external morphology and movement of a living specimen of the minute gastropod Sukashitrochus pulcher (Petterd, 1884) is reported and the findings compared with the reported morphologies of other species of Sukashitrochus and scissurellids more generally. Although some scissurellids exhibit swimming behaviour, there is no evidence that temperate Australian Sukashitrochus species possess this ability. [ABSTRACT FROM AUTHOR]

Systematics of Corbulidae supported by anatomical and conchological studies remains confused and controversial because of the considerable phenotypic plasticity of their shells. Ultrastructural spermatozoan study and molecular analyses have been performed to contribute valuable information, which could be used in taxonomy. Electron microscopy was used to analyse sperm cells from specimens of Caryocorbula (Gardner, 1926) exhibiting shell differences. The spermatozoon was of the aquasperm type, showing short acrosome, barrel-shaped nucleus, midpiece composed of four spherical mitochondria and simple flagellum. In addition, about 860 base pairs of mitochondrial large ribosomal subunit (16S rRNA) were sequenced from each individual. The consistent similarity shared by spermatozoa and DNA sequences from all studied specimens indicated that they belonged to one coherent unit, Caryocorbula caribaea (d'Orbigny, 1853), despite the extraordinary plasticity exhibited by their shells. [ABSTRACT FROM AUTHOR]

Hiatella is one of the most widespread marine bivalve genera, occurring in diverse habitats from the temperate to polar latitudes in both hemispheres, and in fossil strata since almost 150 Myr ago. Despite variation in some biological and morphological traits, characters to resolve the current systematic structure consistently across the range of the genus are not known: all samples are often referred to a single species, Hiatella arctica (L.). Exploring the systematics of Hiatella using partial sequences of three genes (mitochondrial COI, and the nuclear ANT and 28S r RNA), we find high diversity of deep lineages (11-22% p-distance in COI), and identify at least 13 distinct taxa both by heuristic criteria (congruence of the nuclear and mt DNA data) and by coalescence-based analyses. At several localities, two or three of these cryptic species were found in sympatry. In the framework of previous fossil evidence and of hypotheses of paleoceanographical connections, scenarios of the phylogeny and biogeographical history of the identified species at a range of different time scales are outlined. The distinction between the main North Pacific and North Atlantic Hiatella clades and systematic diversification within each of them seem to have followed a Miocene trans-Panamanian invasion. Apart from such earlier intra-basin diversification, the data suggest that three successive counter-invasions from the Pacific to the Atlantic via the Arctic Ocean route have later contributed to the current North Atlantic Hiatella diversity. These invasions probably took place in connection with (i) the Great Trans-Arctic Biotic Interchange in the Pliocene, (ii) the last interglacial period c. 120 kya and (iii) the Holocene, postdating the last glaciation. This sequence of trans-Arctic invasions is largely analogous to that hypothesized for some other boreal-arctic bivalves. [ABSTRACT FROM AUTHOR]

The quantification of lobule shape for Radula spp. shows that there is overlap in lobule shape space occupied by subgenera, such that lobule shape does not always reflect relationships. Morphological convergence caused by lineages repeatedly traversing shared regions of morphospace appears commonplace in Radula, and means that many pairs of relatively unrelated species have similar lobule shapes. When observed over time, as in comparisons between fossil and extant species, this may give the impression of stasis if fossil species resemble modern species by chance, independent of their relatedness. This poses a challenge to relating fossils of known age to extant lineages, particularly when fossils are sterile. Significant rate variation between lineages was identified by Adams' Q-mode analysis, with the fastest subgenus evolving 23 times more quickly than the slowest. Species of subgenus Volutoradula and subgenus Metaradula are apparently over-dispersed throughout lobule morphospace according to Sidlauskas' method; morphometric branch lengths and hypervolumes in other subgenera can be explained by a stochastic process. In contrast, Bayesian analysis of macroevolutionary mixtures ( BAMM) identified a single evolutionary rate as having the highest posterior probability. Consideration of the three independent accessions into auriculate lobule morphospace by Cladoradula and Radula, wherein convergent lobule shapes result from convergent lobule ontogenies and are correlated with bipinnately branched shoot systems and robust primary stems, leads to an ontogenetic hypothesis driven by structural requirements for light interception, under which auriculate lobules are a spandrel. It is speculated that lobules themselves, however, may be a key innovation facilitating radiation into microsites devoid of or depauperate in fungal endophytes. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 178, 222-242. [ABSTRACT FROM AUTHOR]

Lepidochitona pseudoliozonis, a new species of chiton (Polyplacophora: Ischnochitonidae) from the North of the Caribbean. The genus Lepidochitona (Gray 1821) contains relatively small chitons with a distinctive girdle, dorsally clothed with non-overlapping calcareous corpuscles. In the Caribbean, it is represented by four species: L. liozonis (Dall, & Simpson, 1901), L. rosea Kaas, 1972, L. rufoi García-Ríos, 2010 and L. bullocki García-Ríos, 2011. A rutinary morphological inspection of 10 specimens of a Lepidochitona species from the Florida Keys was concordant with L. liozonis (the only species of the genus informed for Florida). They did not show many morphological differences that could justify its separation from the specimens from Puerto Rico (the type locality). However, the comparison of sequences of the mitochondrial gene coding for cytochrome oxidase I (COI) of L. liozonis from Puerto Rico and the Florida specimens showed a divergence of 14%. This divergence is incompatible with a reproductively connected species. In addition to their genetic differences, the new species differs from L. liozonis in having bigger size, longer marginal spicules and a postmucronal slope very concave. [ABSTRACT FROM AUTHOR]

Morphology of the shell, radula, jaw, anatomy and sculpture of the inner wall of the reproductive system are described and compared for three species belonging to theBostryx tortoranusspecies complex. On the basis of these characters, the following changes are proposed:Bostryx martinezi(Hylton Scott, 1965) is removed from synonymy withBostryx tortoranus(Doering, 1879) andBulimulus(Scansicochlea)cicheroiHylton Scott, 1967 is transferred from synonymy withB. tortoranusto synonymy withB. martinezi. As a result of these changes, the number of species ofBostryxknown from Argentina has increased to 19 species.Bostryx tortoranusandB. martineziare redescribed, also the radula and anatomy ofBostryx rudisculptus(Parodiz, 1956) are described for the first time. The main distinctive morphological characters of the three species are: the structure of the shell’s protoconch and teleoconch, radular morphology, location of the secondary ureter opening, the length of the free oviduct with respect to the vagina and the epiphallus with respect to the penis and the bursa copulatrix duct’s inner wall sculpture.Bostryx martineziandB. rudisculptushave restricted distributions and are ecologically endemic, whereasB. tortoranushas a wide distribution and is located in different dry ecoregions. http://zoobank.org/urn:lsid:zoobank.org:pub:A2F21A37-E0ED-454F-A63D-EEC1804D7DFA [ABSTRACT FROM PUBLISHER]

The taxonomy of common northern nudibranch molluscs of the genus Dendronotus in the vast cold regions of Eurasia remains largely unknown. Abundant material collected in many localities from the Barents Sea, via the Arctic region, to the north-west Pacific was analysed for the first time. An integrated approach combining morphological and ontogenetic data with molecular four-gene ( COI, 16S, H3, and 28S) analysis reveals seven species, including three previously undescribed. Dendronotus frondosus ( Ascanius, 1774) and Dendronotus dalli Bergh, 1879 were commonly considered as amphiboreal species; however, according to this study they are restricted to the North Atlantic and the North Pacific, respectively. In the north-west Pacific two new species were discovered, D endronotus kamchaticus sp. nov. and D endronotus kalikal sp. nov., that are externally similar to D. frondosus, but that show significant distance according to molecular analysis and are considerably different in radular morphology. In the North Atlantic a new species D endronotus niveus sp. nov., sibling to North Pacific D. dalli, is revealed. The separate status of North Atlantic Dendronotus lacteus ( Thompson, 1840) is confirmed, including considerable range extension. The essential similarity of early ontogenetic stages of radular development common for species with disparate adult radular morphology (such as D. frondosus and D. dalli) is shown, and its importance for taxonomy is discussed. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

The shell of the European abalone Haliotis tuberculata is a model for studying mechanisms of mollusc shell formation, but the early steps of shell formation and calcification remain poorly documented. The microstructure and the mineralogical and geochemical composition of larval and juvenile shells were investigated by scanning electron microscopy, infrared spectroscopy and ion microprobe analyses (NanoSIMS). Analyses were performed on shells obtained from controlled fertilisations at the hatchery France-Haliotis (Plouguerneau, France) in July 2009 and 2010 using abalone from Roscoff. Shell cross sections revealed the microstructural arrangement of the developing shell, showing progressive biomineral organisation into two differentiated layers, i.e. the outer granular and the internal nacreous layer. Infrared analysis confirmed that the European abalone shell, at every stage of development, was mostly composed of CaCO in the form of aragonite. Variations in trace element composition, i.e. Sr/Ca, were measured in the different stages and correlated with micro-structural changes in the shells. Experimental manganese labelling of live abalones produced cathodoluminescence marks in the growing shell sections. The increase in shell thickness can be used to determine the growth rate of an early adult abalone shell. [ABSTRACT FROM AUTHOR]

Anatomical data on Solariella obscura (Couthouy, 1838) are presented and analyzed. The main features of this species, when compared with other known trochoids, are: ctenidium with thick lamellae; enlarged ureter (that may indicate sexual dimorphism) instead of a modified urogenital papilla; odontophore very different from other trochoids such as Calliostoma, Agathistoma, Monodonta, and Gaza, with short m6, large mj and m4 pairs and absent m8 pair and posterior cartilages; esophageal valve surrounding the odontophore ventrally; anterior and mid-esophagus composed of several thin folds and a very wide cerebral ganglion. Solariella obscura differs from Solariella varicosa (Mighels & Adams, 1842) by having lower spire, spiral cords weaker on the base and axial rib oblique. There are no differences between S. obscura and S. varicosa in the external morphology and radula. These internal anatomical data are described for the first time for a solariellid and might improve our understanding of the relationships within this taxon. [ABSTRACT FROM AUTHOR]

The gastropod Trophon geversianus exhibits shell polymorphisms along its distribution in subtidal and intertidal habitats. Our hypothesis is that morphological and behavioral patterns of T. geversianus represent habitat-specific constrains; subsequently we expect an association between shell morphology, attachment behavior, and habitat. In order to test this hypothesis we compared individuals from intertidal and subtidal habitats, at three sites in Golfo Nuevo (Argentina). We analyzed shell morphology using classic morphometric variables, 3D geometric morphometrics and computing tomography scan. The results were complemented with field observations of attachment to substrate and turning time behavior, as well as of the number of shell scars produced by crab predation. Our results showed differences in shell size and shape between intertidal and subtidal-collected individuals. Centroid size, total weight and shell weight, as well as shell density and thickness were significantly lower in intertidal individuals than in subtidal ones. Gastropods from intertidal habitats presented a low-spired shell and an expanded aperture which might allow better attachment to the bottom substrate, while subtidal individuals presented a slender and narrower shell shape. The number of crab scars was significantly higher in shells from subtidal individuals. Observations of the behavior of gastropods placed at the intertidal splash zone showed 100% of attachment to the bottom in the intertidal individuals, while subtidal specimens only attached in average in 32% of the cases. These latter took 12 times longer to re-attach to the bottom when faced up. Phylogenetic analysis of COI gene fragments showed no consistent differences among individuals sampled in both habitats. All these results suggest that T. geversianus has developed two ecomorphs with distinct morphological and behavioral responses to physically stressful conditions registered in north Patagonian intertidals, as opposed to lower physical stress but higher predation pressure in the subtidal habitats. The findings of this work constitute a starting point in the study of ecological adaptation processes in gastropods from Patagonian coastal environments. [ABSTRACT FROM AUTHOR]

Egypt harbours many species of freshwater snails that transmit parasites causing serious diseases in humans and animals. Due to their significance, it is important to up-date the faunal list regularly. Our objective was to present such an up-date. The twenty eight species known to exist in the country are reviewed, including their synonymy, type localities, diagnostic features and parasitological importance; the shell morphology is illustrated. Besides, snail species thought to be extinct in the country are noted. This review can be used as a field guide for identification of the various species of snails colonising freshwater habitats in Egypt. [ABSTRACT FROM AUTHOR]

The interrelationships and evolutionary history of molluscs have seen great advances in the last decade. Recent phylogenetic studies have allowed alternative morphology-based evolutionary scenarios to be tested and, most significantly, shown that the aplacophorans are sister group to polyplacophorans (chitons), corroborating palaeontological and embryological evolutionary scenarios in which aplacophorans are secondarily simplified from a chiton-like ancestor. Aplacophoran morphology therefore does not represent the plesiomorphic condition for molluscs as a whole. The mollusc crown group radiated in the Early Cambrian, and rapidly thereafter, stem lineages to the major molluscan classes emerged: cephalopods, gastropods, bivalves (= pelecypods), monoplacophorans, rostroconchs (inferred stem scaphopods) and aculiferans. This attests to the fast, adaptive radiation of the crown group during the Cambrian explosion. Kimberella from the latest Ediacaran exhibits several molluscan traits, which justifies its position as a molluscan stem-group member, rather than as a more basal Lophotrochozoan. The interrelationships among the conchiferan molluscs are still a matter of contention and require further palaeontological and molecular phylogenetic scrutiny. [ABSTRACT FROM AUTHOR]

Species of sea hares have been recognized traditionally based on morphological traits, mainly the radula, external coloration, and reproductive anatomy. However, recent studies have shown substantial color variation in some sea slug species. Molecular data have been successfully used to differentiate morphologically similar species of 'opisthobranchs' and resolve questions on the taxonomic value of color. The objective of this paper is to use molecular data in an attempt to elucidate whether specimens of Aplysia brasiliana with distinct colorations and morphologies are actually the same species. To this end, DNA from 14 specimens of A. brasiliana was extracted, including five specimens identified as a distinct morphotype from typical A. brasiliana. Although the two morphotypes have consistent differences in their external morphology and radula, the molecular data confirmed that there are no significant genetic differences between them. This is another example of the need to re-evaluate taxonomic decisions based on morphology in light of molecular evidence. [ABSTRACT FROM AUTHOR]

Few molecular studies have addressed the phylogenetic relationships within Acanthochitonina. Here, we use high-throughput sequencing to determine three mitochondrial genomes of Acanthochitonina. We further explore phylogenetic relationships with expanded taxon sampling based on mitochondrial and nuclear sequence data. Phylogenetic analyses recover two major lineages roughly corresponding to Cryptoplacoidea and Mopalioidea, but the necessity of reassigning multiple genera challenges their conventional definition and that of the families Mopaliidae, Schizoplacidae and Lepidochitonidae. Two mitogenomes share a gene rearrangement that might represent a synapomorphy for Lepidochitonidae. Our phylogenetic results support the reinterpretation of certain morphological characters as homologous, previously assumed to be convergent. They further reveal that major Acanthochitonina lineages were restricted to particular ocean basins, where they diverged into endemisms with disparate morphology. Our results are corroborated by morphological and biogeographical evidence and contribute toward resolving the phylogenetic relationships of Acanthochitonina, and highlight the need for further phylogenetic and systematic studies. [ABSTRACT FROM AUTHOR]

Molluscs are diverse and important enough to receive considerable scientific attention. We herein question recent opinions that the molluscan origin, deep inner relationships, and early evolution have been largely resolved. The traditional Testaria concept implied progressive evolution from worm-like aplacophoran to polyplacophoran and then conchiferan body plans; sole evidence for this came from morphocladistic analyses, which we conclude were confounded by homoplasy. The recently preferred Aculifera-Conchifera concept is supported by some but not all analyses using massive sequence data on rather small and uneven taxon sets. Recent results from mitogenomics indicate that gene-rearrangement events could cause sequence biases overriding potential phylogenetic signal. We discuss recent progress regarding multilocus marker analyses, particularly refining the neglected Serialia hypothesis with Monoplacophora sister to Polyplacophora. This third hypothesis for molluscan relationships is supported by an integrative interpretation and is roughly compatible with available fossil evidence if the first molluscs were small and had a true shell rather than a chiton-like body organization. Despite some claims of consensus, there are substantial discrepancies among recent molecular studies regarding class-level topologies. These may be symptomatic of a plethora of factors and evolutionary processes – obvious or more hypothetical – that might hinder successful reconstruction of early molluscan diversification. [ABSTRACT FROM AUTHOR]

Certain species of chiton (Mollusca, Polyplacophora) have hundreds of small (< 100 µm) eyes embedded in their dorsal shell plates. These eyes each contain a retina, a layer of screening pigment, and a lens. Previously, we demonstrated that the eyes of chitons provide spatial vision. As in other camera-type eyes, the screening pigments in the eyes of chitons absorb off-axis light in order to preserve the contrast of images formed on the retina. Our results indicate that the red-brown, alkali-soluble screening pigment associated with the eyes of the chitonAcanthopleura granulata(Gmelin, 1791) is pheomelanin. Using high-performance liquid chromatography (HPLC) and MALDI-TOF mass spectroscopy, we find that degradingA. granulata’s screening pigment with alkaline hydrogen peroxide produces 6-(2-amino-2-carboxyethyl)-2-carboxy-4-hydroxybenzothiazole (BTCA), a diagnostic marker of pheomelanin. Chitons are the first molluscs demonstrated to use pheomelanin as a screening pigment in their eyes. Our results suggest that the image-forming eyes of chitons may have evolved separately from eyes that employ different types of screening pigment, such as those of most other invertebrates. Further, we hypothesize that change in the expression pattern of tyrosinase – an enzyme responsible for melanin synthesis in many other metazoans – may have contributed to the origin of screening pigments in chitons, a critical step in the evolution of their eyes. [ABSTRACT FROM AUTHOR]

The morphology and internal anatomy of the caudofoveateFalcidens vasconiensisSalvini-Plawen, 1996, are described and a 3D reconstruction of its anatomy is made with the program AVIZO 6.3.1. The detailed body shape, additional sclerite types, digestive system, and nervous system ofF. vasconiensisare described for the first time. The nine specimens studied here were collected off the NW Iberian Peninsula between 150 and 600 m depth during the expeditions DIVA-ArtabriaI 2002 and 2003, Vertidos2004, and ASelva2008. [ABSTRACT FROM AUTHOR]

We describe the reproductive system and morphological expression of imposex in the marine gastropod Gemophos viverratus (Kiener, 1834) for the first time. This species can be used as a bioindicator of tributyltin (TBT) pollution on the west coast of Africa, a region for which there is a lack of information regarding levels and impacts of TBT pollution. Adult G. viverratus were collected between August 2012 and July 2013 in São Vicente Island (Republic of Cabo Verde), at pristine sites on the northeastern and eastern coasts and at Porto Grande Bay, the major harbour in the country. All the females (n = 81) caught outside the bay were normal, but 99% (n = 108) of those collected inside the bay exhibited degrees of abnormal virilization. Seven levels of imposex intensity, from stage 0 (normal) to stage 6 (sterilized females), are described following at least three different pathways of evolution (a, b and c). Female sterilization was caused mainly by abnormal growth of ‘tumour-like’ tissues in the oviduct. A peculiar characteristic of imposex in this species is the development of a distal prostate by females, resembling the same organ exhibited by males. In the laboratory, imposex could be artificially induced by injecting very small doses of TBT into females, demonstrating that TBT is a causative agent of this syndrome. [ABSTRACT FROM PUBLISHER]