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The distinctive morphology, color pattern, and isolated geographic locations of the various proposed taxa of the Voluta musica complex are discussed and specimens of the various taxa are illustrated. Evidence shows that populations of ancestral V. musica became genetically isolated on offshore islands during interglacial times, due to the associated higher sea levels during the Neogene, resulting in a species swarm of closely-related allopatric species. The following taxa are recognized as full species, and these include: Voluta musica, V. carneolata, V. thiarella, V. damula, and V. typica. [ABSTRACT FROM AUTHOR]

A review of the Relegamoria molleri (Iredale, 1936) complex was undertaken using newly sourced material from a number of private research collections and Atlas of Living Australia ("ALA") database, which contains the Australian and Queensland Museums holdings and records. After a detailed review of several hundred specimens including morphological and distributional characters, Relegamoria Iredale, 1936 is reinstated at the generic level and the two previously recognised subspecies R. molleri isabelae Bail, Limpus & Poppe, 2001 and R. molleri vandenbergae Bail, Limpus & Poppe, 2001 are raised to full species and a further nine new species are recognised: Relegamoria aliuamolleri new species, Relegamoria archaeomolleri new species, Relegamoria ariae new species, Relegamoria elsieae new species, Relegamoria charlyi new species, Relegamoria barbaracollinsae new species, Relegamoria annetteae new species, Relegamoria youngorum new species and Relegamoria ashleyfieldi new species. This revision highlights the need for a broader review into the deep-water fauna of Queensland and New South Wales, particularly as more private collections are made available for scientific study. [ABSTRACT FROM AUTHOR]

Twelve new species and subspecies of gastropods are named from three subprovinces of the Carolinian Molluscan Province that occur within the Gulf of Mexico. These include: (from the Floridian Subprovince) Scaphella junonia glicksteinorum n. subsp., Scaphella (Clenchina) carrieae n. sp., and Scaphella (Clenchina) rundoi n. sp. (all Volutidae); (from the Suwannean Subprovince) Conomodulus lambi n. sp., Modulus danielsi n. sp. (both Modulidae); (from the Yucatanean Subprovince) Modulus hunahpu n. sp., Trochomodulus velai n. sp. (both Modulidae), Cinctura salasi n. sp. (Fasciolariidae), Lindafulgur camazotz n. sp. (Busyconidae), Ventrilia jonathoni n. sp. and Ventrilia xbalanque n. sp. (both Cancellariidae), and Bulla occidentalis morai n. subsp. (Bullidae). A new scaphelline volute subgenus, Garciavoluta n. subgen. (type species: Aurinia (Garciavoluta) mcginnorum), is also described. [ABSTRACT FROM AUTHOR]

This contribution presents a comprehensive analysis of the Puerto Níspero deposits in Costa Rica, focusing on their lithofacies and associated textural analysis, paleoenvironmental interpretation, and stratigraphic position. The study identifies seven distinct lithofacies types, revealing a diverse range of textures and organisms. Notable discoveries include corals from various families and genera, nerineid gastropods, and abundant rhodoliths. The stratigraphic columns, exceeding 100 m in thickness, provide valuable insights into the paleoenvironmental conditions, suggesting a transition from offshore open marine settings to a shallow platform and a protected lagoon. The presence of the planktonic foraminifers Rugoglobigerina rugosa and Globotruncanella sp., along with the gastropods and corals Nerinea sp., Rostellana sp., and Marcelohelia sp., indicates a Maastrichtian age. Based on these findings, we propose a new lithostratigraphic unit, the Puerto Níspero Formation, thus challenging the previous correlation with the Barra Honda Formation. • Analysis of stratigraphic columns uncovers seven distinct lithofacies types. • Findings include corals, rudists, nerineids, and rhodoliths. • Transition from low-energy offshore area to shallow, warm, and protected waters. • Cretaceous marker organisms justify proposing a new lithostratigraphic unit. • The Puerto Níspero Formation challenges previous knowledge on the outcrop. [ABSTRACT FROM AUTHOR]

Ericusa ngayawang sp. nov. is described from shells preserved in the Middle Miocene Cadell Formation in the western Murray Basin of South Australia. At the time the Murray Basin was part of the Southeastern Australian Marine Biogeographic Province. Ericusa ngayawang is a small heavily costate species of Ericusa with clear affinities to the Early Miocene E. atkinsoni of Victoria and Tasmania but can be distinguished from it by its smaller size, more slender proportions and its heavily costate body whorl. Ericusa atkinsoni and its relative, E. macroptera, inhabited the basins to the east of the Murray Basin during the Late Oligocene and Early Miocene but were extinct there before the end of the Burdigalian Stage of the Early Miocene. The persistence of E. ngayawang into the Langhian Stage of the Middle Miocene is another piece of evidence for partial biogeographic isolation of the western Murray Basin from the rest of the Southeastern Australian Province during the Miocene. [ABSTRACT FROM AUTHOR]

Ericusa ngayawang sp. nov. is described from shells preserved in the Middle Miocene Cadell Formation in the western Murray Basin of South Australia. At the time the Murray Basin was part of the Southeastern Australian Marine Biogeographic Province. Ericusa ngayawang is a small heavily costate species of Ericusa with clear affinities to the Early Miocene E. atkinsoni of Victoria and Tasmania but can be distinguished from it by its smaller size, more slender proportions and its heavily costate body whorl. Ericusa atkinsoni and its relative, E. macroptera, inhabited the basins to the east of the Murray Basin during the Late Oligocene and Early Miocene but were extinct there before the end of the Burdigalian Stage of the Early Miocene. The persistence of E. ngayawang into the Langhian Stage of the Middle Miocene is another piece of evidence for partial biogeographic isolation of the western Murray Basin from the rest of the Southeastern Australian Province during the Miocene.

This study provides the taxonomic description of eight species of Nannamoria Iredale, 1929 from Miocene deposits of Victoria and South Australia and Pliocene deposits of Flinders Island Tasmania, Australia. The following new species are described, discussed and compared to their congeners: Nannamoria costatum n. sp., Nannamoria flindersi n. sp., Nannamoria hiscocki n. sp., Nannamoria gnotuki n. sp., Nannamoria alquezae n. sp., Nannamoria cadella n. sp., Nannamoria malonei n. sp. and Nannamoria persimilis n. sp. Various aspects of Nannamoria evolution are discussed. [ABSTRACT FROM AUTHOR]

Three new scaphelline volutes, belonging to the genera Scaphella and Volutifusus, are described from Pliocene formations in southern Florida. The new taxa include Scaphella kendrae n. sp. from the Sarasota Member, Murdock Formation (Zanclean Age), Volutifusus dougsheltoni n. sp. from the Buckingham Member, Tamiami Formation (early Piacenzian Age), and Volutifusus kissimmeensis n. sp. from the Fruitville Member (Unit 2 Kissimmee facies equivalent), Tamiami Formation (late Piacenzian Age). [ABSTRACT FROM AUTHOR]

We report the complete mitochondrial genome sequence of Harpovoluta charcoti, a circum-Antarctic species of volutid gastropod inhabiting bathyal soft bottom substrates. The mitogenome is 15,487 bp in length, has a base composition of A (28.3%), T (37.3%), C (16.0%) and G (18.4%), and contains 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. Gene order and strand orientation are the same as in other non-toxoglossan neogastropods. Phylogenetic analyses support the monophyly of Volutidae, but not of the subfamilies Amoriinae or Cymbiinae as currently circumscribed.

A new species of Amoria Gray, 1855 (Gastropoda, Volutidae) is described from shells dredged off the Australian mid-east coast (Cape Moreton, Queensland and Tweed Heads, New South Wales). Amoria thorae sp. nov. shows a number of similarities in shell form and/or colour pattern to two other small Amoria, A. necopinata Darragh, 1983 and A. benthalis McMichael, 1964 and to the much larger A. undulata (Lamarck, 1804) but can be readily distinguished from these and all other members of the genus by the combination of small shell size, fusiform shape, high spire, equalsized thick columellar plaits and a single, large undulation of the axial lines. [ABSTRACT FROM AUTHOR]

We sequenced the complete mitogenome of a specimen of Cymbiola nobilis (Neogastropoda, Volutidae) from Phú Quốc Island in Vietnam. The mitogenome of this predatory sea snail is 16,314-bp long and comprises the typical set of genes encoding 13 proteins, 2 rRNAs, and 22 tRNAs. It features a complex control region that contains two copies of an inverted repeat sequence separated by an AT-rich region, a characteristic previously observed in a few other gastropods. Phylogenetic analysis based on all protein-coding genes revealed that the Volutidae form a strongly supported clade.

The Voluta polypleura - demarcoi species complex of the Caribbean Province volutid fauna are reviewed, illustrated, and a number of taxa are revised. [ABSTRACT FROM AUTHOR]

A new subspecies of Scaphella junonia has been discovered off the Alacranes Reefs, along the northernmost edge of Campeche Bank, Yucatan Peninsula of Mexico. The new subspecies, here named Scaphella junonia curryi, differs from the other four known S. junonia subspecies in having the narrowest and most elongated shell, having the strongest and most extensive ribbed sculpture on the spire whorls, and in having a different color pattern composed of very large, almost fused rectangular spots. The new subspecies is confined to the edge of the Campeche Escarpment off the northern Campeche Bank islands and reefs. [ABSTRACT FROM AUTHOR]

The Malacology Collection of the Museo de La Plata contains more 13,000 lots from various regions of Argentina and other South American countries. The Collection also includes 511 type lots. Among the oldest type specimens are a large series of marine gastropod from Patagonia which were studied by Fernando Lahille in 1895. He was one of the first's naturalists of the Museo de La Plata, and there between 1893 and 1899, he made several studies in zoology. During that time, he described three species and forty varieties of Volutidae. Herein, we compare Lahille's type specimens, label data, number, and specimen information to the original descriptions and illustrations of these taxa. Each taxon has been photographed in multiple views. This historic type material is entirely composed of shells. This work is the first of a series of photographic catalogues of type material from the Malacology Collection of the Invertebrate Division of Museo de La Plata. [ABSTRACT FROM AUTHOR]

We report the complete mitochondrial genome sequence of Harpovoluta charcoti, a circum-Antarctic species of volutid gastropod inhabiting bathyal soft bottom substrates. The mitogenome is 15,487 bp in length, has a base composition of A (28.3%), T (37.3%), C (16.0%) and G (18.4%), and contains 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. Gene order and strand orientation are the same as in other non-toxoglossan neogastropods. Phylogenetic analyses support the monophyly of Volutidae, but not of the subfamilies Amoriinae or Cymbiinae as currently circumscribed. [ABSTRACT FROM AUTHOR]

The gastropods Odontocymbiola pescalia and Provocator corderoi and their egg capsules were collected by the R/V Puerto Deseado from the Mar del Plata Submarine Canyon (~ 37°53′S, at depths of 291–1404 m) and from Burdwood Bank (~ 54°27′S, 128–785 m). Odontocymbiola pescalia egg capsules measured 15.67 ± 3.38 mm in diameter. They were subspherical in shape with an external calcareous layer. Each egg capsule contained 3–5 embryos and white material as extra embryonic food. Embryos grew to a size of up to 9.3 ± 1.1 mm in mean shell length before hatching as crawling juveniles. The spawn of P. corderoi consisted of a single dome shaped egg capsule of 14.17 ± 1.5 mm in diameter, attached to hard substrata by a basal membrane with a rounded outline. A curved semilunar furrow (seam) on one side of the capsules was always present. The number of embryos per capsule was 2–6. Embryos hatched as crawling juveniles with a shell length of 5.9 ± 0.6 mm. The size and number of whorls in the hatchling shell suggested a slow rate of development, akin to many other deep-sea invertebrates. The egg capsules and reproductive development strategies of both species were compared with those from other congeneric representatives. [ABSTRACT FROM AUTHOR]

Voluta musica es un gasterópodo dioico endémico del Caribe sur. El TBT y el Cu, son potenciales causantes del imposex, fenómeno donde las hembras desarrollan un pene y/o vaso deferente. El objetivo fue determinar la incidencia de imposex en V. musica en el noreste de la Península de Araya. Se seleccionaron tres localidades y se captura-ron mensualmente 15 individuos durante un año para determinar: (1) talla de los individuos; (2) sexo y presencia de imposex; (3) índice Largo Relativo del Pene (RPLI). Se realizó histología de la gónada de los individuos. Se determinó TBT y Cu en el sedimento de cada localidad. En Isla Caribe, el 24.5% de las hembras presentó imposex, y se halló 3.9ngSn/g de TBT; en Isla Lobos, el 12% de las hembras desarrollaron imposex; en Bajo del Cuspe no se observó imposex. Se halló Cu en mayor concentración en Isla Lobos. Las gónadas femeninas con imposex no demos-traron masculinización. El mayor porcentaje de imposex coincide con la localidad de mayor tráfico de embarcacio-nes y con mayor nivel de TBT (Isla Caribe). No se eviden-ció esterilización, sin embargo la presencia de TBT, Cu e imposex son potenciales amenazas para las poblaciones de V. musica en la región. Hasta ahora, en Venezuela no se está tomando ninguna medida de control sobre este tema en particular, posiblemente por la escasez de información y orientación de las investigaciones hacia este tema, pero que sin duda se debería tomar en cuenta en las políticas para la conservación de la biodiversidad

Teniendo en cuenta la intensa actividad pesquera artesanal y subsecuente fuente adicional de alimento como carroña en Isla Caribe, se esperaría un efecto sobre algunos parámetros poblacionales de V. musica como: mayor número de ovicápsulas, individuos de tallas mayores y densidades de caracoles adultos mayores. Con el presente trabajo se desea conocer la abundancia, estructura de talla y fecundidad de Voluta musica en tres sitios de la costa norte de la Península de Araya en las que existen actividades de pesca diferenciales. Se realizaron muestreos mensuales entre 2008 y 2009 en Isla Caribe, Isla Lobos y Bajo Cuspe, en cada uno con 3 áreas de 40m². La abundancia varió de 5ind/120m² a 30ind/120m², con diferencias significativas entre los sitios (F= .77; p

The genus Adelomelon Dall, 1906 comprises a group of South American marine gastropods. We present updated information on the genus Adelomelon, with emphasis on the status and location of type material, including that of junior synonyms. Scaphella arnheimi Rivers, 1891 and Voluta paradoxa Lahille, 1895 are removed from the synonymy of Adelomelon ancilla (Lightfoot, 1758) and Adelomelon barattinii Klappenbach and Ureta, 1966 is included. The subgenus Weaveria Clench and Turner, 1964 is placed in synonymy with Adelomelon s.s. A key to the species of Adelomelon is provided.O gênero Adelomelon Dall, 1906 engloba um grupo de gastrópodes sul-americanos. Apresentamos informações atualizadas sobre o gênero Adelomelon, com ênfase no status e localização do material-tipo, também dos sinônimos juniores. Os táxons Scaphella arnheimi Rivers, 1891 e Voluta paradoxa Lahille, 1895 são removidos da lista sinonímica de Adelomelon ancilla (Lightfoot, 1758) e Adelomelon barattinii Klappenbach and Ureta, 1966 é incluído. Também o subgênero Waveria Clench and Turner, 1954 é colocado na lista sinonímica de Adelomelon s.s. e uma chave para as espécies de Adelomelon é apresentada.

Butyltins (BTs) were found in sediments and body tissues of the edible gastropodOdontocymbiola magellanica, in which imposex has been recorded since 2000. BTs in sediments ranged from < MDL to 174.8 ng (Sn) g−1for TBT, < MDL to 19.2 ng (Sn) g−1for DBT, and < MDL to 71.8 ng (Sn) g−1for MBT. In body tissues BTs varied from < MDL to 147.1, < MDL to 77.0 and < MDL to 345.3 ng (Sn) g−1for TBT, DBT and MBT, respectively. BT concentrations were higher in gonads and digestive glands than in the albumen gland and foot (edible). The highest concentrations of BTs in both sediments and gastropods were found in the harbour area, decreasing with distance to the harbour and areas with less maritime traffic. The Biota-Sediment Accumulation Factor (BSAF) in the different organs was between 0.02–0.42, 0.09–0.35 and 0.08–5.25 for TBT, DBT and MBT, respectively. There were positive correlations between concentrations of BTs in sediments and gastropod body tissues, suggesting that xenobiotic accumulation inO. magellanicaoccurs mainly through contaminated sediments, rather than water or the food chain. Considering current sediment quality guidelines, our results indicate that acute toxic effects would be expected from TBT exposure, which represents a serious environmental threat for the benthic community. Although the levels of BTs found in the foot of this edible gastropod did not exceed the recommended Tolerable Daily Intake in polluted areas, they should be monitored to ensure the safety of seafood consumers. The alternative antifouling biocides Irgarol and Diuron were not detected in sediments. [ABSTRACT FROM AUTHOR]

The radular morphology ofZidona dufresneiwas studied by optical and scanning electron microscopy. We analysed the variability among and within three populations distributed along the southwestern Atlantic Ocean coast, considering the hypothesis that the isolation among populations favours adaptive phenotypic variation, which is also expressed at the radular level. Populations selected for this study differ in their maximum individual size, growth rate, size and age at maturity, and fecundity. This study provides the first analysis of the interpopulational variability of the radula ofZidona dufresneiand the first description of its morphology.Zidonia dufresneiexhibited a rachiglossate radulae composed of rows of tricuspid teeth (radular formula: 0+R+0). No differences in tooth shape among populations and sexes were observed. However, significant interpopulational differences in the height of the rachidian cusp and total length of the radula were detected. Specimens from San Antonio Bay showed the lowest values for all radular variables. Positive significant relationships between total shell length and the height of the rachidian cusp and total length of the radula were found, while the number of rows remained relatively constant regardless of size. The larger morphotypes had a longer radula because of an increase in the height of the rachidian cusp. No sexual dimorphism was observed in any morphometric variables of the radula. The results suggest that populations distributed along the Argentine Sea are homogeneous for radular morphology, despite the differences in life history traits, which may be linked to a similarity in feeding habits across populations. [ABSTRACT FROM PUBLISHER]

Adelomelon indigestus von Ihering, 1908 is known to be a synonym of Adelomelon beckii (Broderip, 1836) but the taxonomic status of its type material was not previously clear. The specimens cited in the original description of A. indigestus were located and recognized as syntypes. Under the rule of the International Code of Zoological Nomenclature, the type locality is proposed to include Guaratiba (Rio de Janeiro) and São Sebastião (São Paulo) both on the southeastern littoral of Brazil.

Voluta musica is a dioecious marine gastropod endemic of the South Caribbean. Tributyltin (TBT) and copper (Cu) are potential inducers of imposex, an endocrine disorder by which females develop a penis and/or vas deferens. The goal of this work was to determine the imposex incidence in V. musica populations from Northeastern Península de Araya. For this, we selected three sites (Isla Caribe, Isla Lobos and Bajo Cuspe) and made monthly samplings of 15 snails in each site, during one year, and determined: (1) sizes; (2) sex and imposex incidence and (3) the Relative Penis Length Index (RPLI). We also performed histological analysis of the gonads, and measured TBT and Cu concentrations in sediments from the studied localities. Our results showed that the total number of sampled females affected by imposex was 24.5% at Isla Caribe, 12% at Isla Lobos, and none at Bajo Cuspe. In sediments, Cu was detected mostly in Isla Lobos. The female gonads with imposex did not show any development of male cells in any of the sampled sites. The higher percentage of females with imposex matched with the higher boat traffic locality, and higher TBT level (Isla Caribe). No esterilization was evident in this work, nevertheless, the presence of TBT and Cu in the sediments and females with imposex were considered as a potential threat to V. musica populations in this region. In Venezuela there is no control over this particular issue, possibly because of the lack of information and research in this topic, but certainly, this information will be useful in biodiversity conservation policies. [ABSTRACT FROM AUTHOR]

We sequenced the complete mitogenome of a specimen of Cymbiola nobilis (Neogastropoda, Volutidae) from Phú Quốc Island in Vietnam. The mitogenome of this predatory sea snail is 16,314-bp long and comprises the typical set of genes encoding 13 proteins, 2 rRNAs, and 22 tRNAs. It features a complex control region that contains two copies of an inverted repeat sequence separated by an AT-rich region, a characteristic previously observed in a few other gastropods. Phylogenetic analysis based on all protein-coding genes revealed that the Volutidae form a strongly supported clade. [ABSTRACT FROM AUTHOR]

This study describes euspermatogenesis and paraspermatogenesis in Adelomelon ancilla (Volutidae) and compares them with the same processes in other caenogastropods. Spermatogenesis in A. ancilla followed the general developmental pattern of caenogastropods. The pattern of nuclear condensation involves granular, fibrillar, lamellar and homogenous electron-dense phases. Acrosome development begins with the posteriorly located proacrosomal vesicle arising from the Golgi complex in euspermatids. The proacrosomal vesicle develops into a preattachment acrosome which, together with the Golgi body, later moves towards the apex of the nucleus. In the early stage of paraspermatogenesis, the pattern of chromatin distribution in dense patches, together with the cytoplasmatic characteristics of paraspermatogonia, allows the recognition of the apyrene line from the euspermatogonia. Later features, including the peripheral condensation of nuclear chromatin followed by nuclear invagination, the posterior breakdown into nuclear vesicles (‘caryomerites’), centriole multiplication and the synthesis of secretory products, are the most conspicuous changes in the process of paraspermatogenesis. [ABSTRACT FROM PUBLISHER]

Giménez J. 2010. Euspermatozoa and paraspermatozoa in the volutid gastropod Odontocymbiola magellanica, Patagonia, Argentina, Southwestern Atlantic Ocean. - Acta Zoologica (Stockholm) 92: 355-362. The ultrastructure of mature spermatozoa and paraspermatozoa of Odontocymbiola magellanica is investigated . Euspermatozoa consist of: (1) a tall, conical acrosomal vesicle (with a short basal invagination, constricted anteriorly); (2) a rod-shaped, solid and highly electron-dense nucleus; (3) an elongate midpiece consisting of the axoneme sheathed by helical mitochondrial elements each exhibiting a dense U-shaped outer layer; (4) an elongate glycogen piece; (5) a dense annulus at the junction of the midpiece and glycogen piece; and (6) a short free-tail region. Paraspermatozoa of O. magellanica are vermiform and dimorphic. First type contain approximately 14-17 axonemes (arranged peripherally and interspersed with microtubules) and numerous oblong dense vesicles, numerous less dense (round) vesicles, and scattered mitochondria; the second type contains 38-45 axonemes peripherally arranged and closer to the core region of the cell and occasional mitochondria. Most of the euspermatozoal features of O. magellanica are also observed in many neotaenioglossans and neogastropods. However, the U-shaped outer layer of each mitochondrial element has only been previously reported in the Volutidae subfamily Zidoniinae. It is now reported here in the subfamily Odontocimbiolinae and may prove to be a diagnostic feature of the Volutidae family. [ABSTRACT FROM AUTHOR]

Abstract: Tributyltin (TBT) has been widely used as antifouling in marine environments, producing imposex in gastropod females (i.e. neoformation of a vas deferens and/or a penis) and shell malformations in bivalves. However, effects of TBT and other pollutants from high marine traffic zones on the shell of gastropods have been little explored. Shell shape in volutids Odontocymbiola magellanica from a harbor polluted site (P) has been compared with that of animals from a non-polluted location (NP) using 3D geometric morphometrics. Also, the microstructure and density of shells from both populations were analyzed. Prior studies made in the same area (Golfo Nuevo, Patagonia, Argentina) based on traditional multivariate morphometrics showed some differences in size but was unable to detect differences in shell shape among O. magellanica from P and NP areas. Departing from 3D geometric morphometrics, scanning electron microscopy (SEM) and computed tomography (CT) techniques, we have registered the presence of patent differences on shell shape and structure in animals from polluted (P) and non-polluted (NP) areas. In 100% of shells from the NP area we register three calcium carbonate layers (prismatic, cross lamellar and amorphous) and higher densities, while in 50% of the shells collected at the P area the external layer (amorphous) was lacking. Furthermore, a body weight loss of around 30% and a shell weight loss of 20% were registered in animals from the P area. Our combined results suggest that the coordinated use of 3D geometrics morphometrics, CT scan and SEM could be of great utility in order to detect the effect of environmental variables on Neogastropods shell shape and structure. [ABSTRACT FROM AUTHOR]

Odontocymbiola magellanica is the only known South American volutid gastropod that deposits calcareous egg capsules. The spawn is moulded and fixed to flat or convex surfaces by the female's ventral pedal gland, during an hours-long process in which the female adopts a stereotyped posture and appears nonreactive to most external stimuli. Microscopically, the different cells of the ventral pedal gland show features suggesting their participation in the secretion of both the organic matrix and the calcium component of the calcareous layer. The latter consists mainly of numerous spherspherulites that are packed together around cylindrical, septated spaces which traverse the spherspherulitic layer and attach to the membranous layers surrounding the capsule cavity. These septated spaces should ensure permeability of the capsule wall, which is necessary for gas exchange and excretion by the embryo. The calcareous layer is made of high-magnesium calcite, a calcium carbonate polymorph in which Ca is partially substituted by Mg in the calcite lattice. Mg substitution is thought to confer a greater crack resistance to the mineral; it is found in many invertebrates, but apparently has not been reported before in molluscs. Odontocymbiola magellanica is a long-lived species, investing heavily in its egg capsules. [ABSTRACT FROM PUBLISHER]

The imposex incidence and TBT pollution were investigated along 4,700km of Argentinean coast, including city harbors and proximal zones without marine traffic. We analyzed 1805 individuals from 12 gastropod species, including families Volutidae, Muricidae, Nassariidea, Calyptraidae, Marginellidae, and Buccinidae, and found the imposex phenomenon for the first time in six species. In high marine traffic zones, TBT pollution was registered and the percentage of imposex was high, while these occurrences were null in areas without boat traffic. The species that best reflect the degree of imposex were those inhabiting sandy/muddy or mixed bottoms. TBT determination and imposex incidence indicate that pollution was focused only in ports with high marine traffic or in areas where ship hulls are painted. This is the first report of an imposex-sediment approach to evaluate organotin contamination along the coast of a South American country. [Copyright &y& Elsevier]

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Abstract: In this study we compare the composition, structure and biomass of the species assemblage in the Patagonian scallop management unit “Reclutas” (39°00′–39°30′S and 55°45′–56°05′W), in areas subjected to fishing effort (FG) and in the exclusion area (REX), between 1998 and 2002. Data obtained during 1995 and previous to the beginning of the scallop fishery are also considered as baseline condition. No differences in species richness or species composition were detected between areas in the study period. Patagonian scallop biomass was always higher at REX, but by-catch biomass was similar in both areas. The kind of analysis made during this study only allowed us to detect differences in the Patagonian scallop biomass between areas during the study period, while by-catch biomass, as a whole, apparently presented no differences between disturbed and undisturbed areas. Nonetheless, ABC curves in FG in 1998 matched with an undisturbed area, but from 2001 they showed a pattern coincident with a moderately disturbed area. In REX, the pattern observed in 1998 was not quite clear, but in 2002, this unfished area matched with and undisturbed area, as expected for an exclusion area. In addition, multidimensional analysis suggested a differentiation between FG and REX after 1998. Based on analysis of species (dis)similarities we could attribute this differentiation to an increase in predators biomass (Volutidae) and the detritivore ofiuroid Ophiactis asperula, a decrease in the fragile species (Sterechinus agassizii) and the target species of the fishery, Zygochlamys patagonica, and the founding of Chaetopterus variopedatus and Idanthyrsus armatus tubes in the fishing ground. [Copyright &y& Elsevier]

Members of Odontocymbiola magellanica (Volutidae, Odontocymbiolinae) inhabit Argentinean waters from 35°S to the Magallanes Strait. The reproductive biology of this potential fishery resource has not been studied before. Male individuals reach maturity at 80 mm and females at 90 mm, corresponding to ∼7 and 8 years of age, respectively. Mating was observed in the field in all seasons and females possess live spermatozoa in the bursa copulatrix all year round, suggesting that living sperm can be preserved for several months. Major oviposition events occurred July (winter) to December (summer) during the 5 years sampled, as characterized by aggregation of females coincident with increasing photoperiod from winter to summer solstices, and not, apparently, by increase in water temperature. Males showed gametogenic activity throughout the year. Gamete resorption occurred in both sexes. Ultrastructural studies showed that oocytes are attached to companion cells, which enables cell–cell communication and provides support until evacuation; males showed normal sperm cells and two types of parasperms. If populations of O. magellanica are commercially exploited in the future, we propose a minimum catch size of 100 mm, and a ban on the collection of females and egg capsules during the reproductive season. [ABSTRACT FROM AUTHOR]

Abstract: We analyzed the structure of the megabenthic gastropod assemblages on the Uruguayan and northern Argentinean shelf and slope. Our analysis determined that there are two major biologically distinct assemblages which occurred in a 210,000km2 area showing conspicuous environmental gradients and large frontal areas: (a) an assemblage associated with the zone under the influence of the freshwater discharge of Río de la Plata and the shallow waters of the inner shelf and (b) an assemblage associated with marine zone in the outer shelf, which includes Magellanic (Subantarctic) and subtropical faunas. A multivariate analysis demonstrated a significant correlation between the environmental and biological matrix. This evidence suggests a noticeable effect of the physical environment on the spatial structure of the assemblage. We suggest that the current distribution patterns are caused by two different processes operating together: while processes operating at ecological time scales (e.g. differential tolerances to salinity and depth) determine most of the structure observed at the inner shelf, the presence of two contrasting water masses over the outer shelf determine a biogeographic boundary for the benthic fauna, linked to shifting climatic factors influencing species niche dynamics over evolutionary time scales. Thus, at the spatial scale here considered, ecological and historical processes must be considered when attempting to understand which factors determine the current structure of benthic assemblages at regional scales. [Copyright &y& Elsevier]