To broaden the anatomical knowledge of marine bivalves, detailed gross anatomical studies of 20 species from the Florida Keys are presented, representing 19 families: Solemya occidentalis Deshayes, 1857 (Solemyidae), Propeleda carpenteri (Dall, 1881) (Nuculanidae), Arcopsis adamsi (Dall, 1886) (Noetiidae), Limopsis aff. cristata Jeffreys, 1876 (Limopsidae), Brachidontes exustus (Linnaeus, 1758) (Mytilidae), Isognomon alatus (Gmelin, 1791) (Isognomonidae), Hyotissa mcgintyi (Harry, 1985) and H. hyotis (Linnaeus, 1758) (Gryphaeidae), Pinna carnea Gmelin, 1791 (Pinnidae), Spondylus americanus Hermann, 1781 (Spondylidae), Plicatula gibbosa Lamarck, 1801 (Plicatulidae), Anomia simplex d'Orbigny, 1853 (Anomiidae), Carditamera floridana Conrad, 1838 (Carditidae), Entodesma beana (d'Orbigny, 1853) (Lyonsiidae), Codakia orbicularis (Linnaeus, 1758) (Lucinidae), Chama macerophylla Gmelin, 1791 (Chamidae), Lamychaena hians (Gmelin, 1791) (Gastrochaenidae), Polymesoda floridana (Conrad, 1846) (Cyrenidae), Laevicardium serratum (Linnaeus, 1758) (Cardiidae) and Scissula similis (J. Sowerby, 1806) (Tellinidae). These taxa represent various clades of the class Bivalvia and interface with broader regional and phylogenetic studies (e.g., the Bivalve Tree of Life,  http://www.bivatol.org, and Bivalves-in-Time-and-Space,  http://www.bivatol.org/bits), in which many serve as exemplar species in different contexts. These descriptions provide the most complete anatomical descriptions yet presented for all species, most especially for Solemya occidentalis, Limopsis aff. cristata, Hyotissa mcgintyi, H. hyotis, Carditamera floridana, Entodesma beana, Chama macerophylla and Polymesoda floridana, for which no or only minimal anatomical information has been previously published. This work presents the first anatomical description of any species of Scissula, based on S. similis. Two controversial characters — the promyal passages (in Hyotissa spp., in Anomia simplex noted here for the first time, and in Crassostrea reported in the literature) and the various kinds of posterior apertures and siphons present in the species examined and across the Bivalvia — emphasize the need for further comparative study to confirm homologies. Conspecificity of Brazilian material with that from the North American coast is clarified for all species, resulting in nine species being removed from Brazilian checklists (S. occidentalis, B. exustus, I. alatus, P. carnea, C. floridana, C. macerophylla, L. hians, L. serratum, and S. similis). Pertinent anatomical characters are summarized in a data matrix, and an analysis is provided to demonstrate the utility and resolving power of such characters (but from this limited taxon samp

The freshwater mussel Limnoperna fortunei is adapted to colonize a wide range of aquatic environments, and its ability to contend with environmental stress through phenotypic plasticity has allowed this species to successfully colonize and become established in new regions. Only limited information is currently available on the wide intraspecific variability of this species in response to environmental heterogeneity. Here, we tested the hypotheses that (1) growth and body weight of mussels from a highly polluted environment differed from those from a less polluted habitat, and (2) growth parameters estimated in this study differed from those reported for other invaded ecosystems. We conducted controlled field experiments in two study sites with differing levels of pollution. To compare our results to those reported elsewhere, we considered growth data from studies performed in different locations. We found that mussels from the more polluted habitat showed lower shell growth and body weight than those from the less polluted environment. We also observed differences in the growth performances of the golden mussel between our estimates and those from other invaded habitats. Our findings provide useful information to better understand the striking intraspecific variability of this species in response to stressful conditions. Knowledge on the phenotypic plasticity of L. fortunei is essential for predicting and managing this species.

Leptochiton sanmatiensis, new species, is described from shallow-waters of Argentina. The species is characterized by having a quincuncial arrangement of tegmental granules on head valve, lateral areas of intermediate valves and postmucronal area of tail valve, and a longitudinal arrangement of these structures on the central areas of intermediate valves; each granule having a macraesthete and four micraesthetes. In addition, the new species has pectinated dorsal scales, with 14–21 ridges; a low number of ctenidia (up to six on each side in the largest specimens); and the second lateral tooth with three denticles in the cusp. The species lives on small gravel and shells.

Zidona dufresnei is a carnivorous snail that plays an important role in the trophic web as a top predator. It is a threatened species due to high levels of fisheries exploitation. In this study, we describe the morphology of the digestive gland of Z. dufresnei from Mar del Plata, Argentina, and discuss the function and the cycle of activity of the different cell types. Histological analysis reveals two types of tubules: type 1 tubules composed of digestive and basophilic cells and type 2 tubules lined by basophilic cells only. Pyramidal basophilic cells contain lipofuscin and a large amount of rough endoplasmic reticulum, which suggests that these cells are responsible for the secretion of digestive enzymes that initiate the extracellular digestion of the food. Columnar digestive cells exhibit large membrane-bound vesicles that contain proteoglycans, neutral glycosaminoglycans and small amounts of lipid and lipofuscin. The presence in digestive cells of many endocytic vesicles and residual lysosomal bodies, as evidenced by the presence of lipofuscin pigments in the apical region, indicate that digestion is completed intracellularly within these cells. The digestive cells are subject to cyclical changes involving four phases: initial, digestion, fragmentation, and disintegration stages.

We developed length-mass regressions for 16 aquatic gastropods collected from 27 springs in Nevada, United States. The relationship between shell length and body mass for all species was best described by fitting a power function. The mean value of the exponent b (2.40 ± 0.39) was lower than reported for other aquatic gastropods, particularly for smaller genera, such as Pyrgulopsis and Tryonia. Length-mass regressions of gastropods showed intraspecific variation, as well as spatiotemporal variation among the same species. Certain habitat characteristics, especially water temperature, may play a key role in determining growth rates and ultimately length-mass regressions in this study. Although the power term b showed high variability when the same species (Melanoides tuberculata, Pyrgulopsis lockensis, and Pyrgulopsis turbatrix) were collected from different springs, the power term was similar when the same species (Pyrgulopsis marcida) was collected from the same spring during different seasons and years. Therefore, we suggest that published equations should be used with caution and only when habitat characteristics and length ranges are similar compared to those in the literature.

The 46 names of species of marine bivalves and gastropods made available by Grabau & King in 1928 are discussed. Probable or possible type material for all but 13 of these taxa has been located in the Institute of Oceanology, Chinese Academy of Sciences. Of these taxa, nine are regarded as valid, the rest being junior synonyms. The valid taxa are: Verilarca interplicata, Collisella peitaihoensis, Rissoina barbara, Rissoina bureri, Epitonium scalare minor, Gradatiscala gradata pygmaea, Nassarius gregarius, Terebra bellanodosa and Mangelia dobsoni, all Grabau & King, 1928. Brief biographies of Amadeus William Grabau (1870–1946) and Chinese malacologist Sohtsu Gee King (1886–1949) are provided.

A cytogenetic study was carried out by means of standard and NOR-FISH staining methods on the chromosomes of four Alopiinae door snails, two species of the Delimini tribe (Siciliaria paestana and Papillifera bidens) and two species of Medorini tribe (Leucostigma candidescens and Medora sp.). The two Delimini species and Medora sp. showed similar karyotypes, concerning the number of chromosomes, 2n = 62, and the first metacentric pair of chromosomes clearly bigger than the other pairs, but differed in the number of the telocentric pairs: none in P. bidens, four in S. paestana and, even, 21 in Medora sp. Leucostigma candidescens had 2n = 48, all biarmed chromosomes. Loci of NORs were on a single medium small chromosome pair in all the four studied species. The obtained results evidence a relevant degree of intergeneric karyotypic diversity in Alopiinae, concerning both chromosome number and/or shape. The data allow us to make a hypothesis on the evolutionary chromosome trends for this door snail subfamily.

Asolene platae is a freshwater snail of the Ampullariidae native from La Plata River basin in South America. Water temperature has an overwhelming influence on the biology of apple snails, though there are no systematic studies related to the thermal biology of this species. The effect of temperature on the activity, growth and mortality of A. platae was studied through laboratory experiments using constant temperatures of 15, 20, 25, 30 and 35°C. The lower threshold and cumulative degree-days for the embryonic development were estimated under fluctuating temperature. Water temperature had a significant effect on the activity of A. platae, being almost null at 15°C, reaching its maximum in the range 25–30°C and decreasing above 30°C. Regardless of temperature, snails remained resting nearly half of the time, exhibiting less activity than other apple snails across similar temperatures. Mortality was higher for hatchlings than for adults at all temperatures with the exception of 35°C, which resulted in high levels of mortality for both groups. Growth of hatchlings was significantly affected by temperature, being highest between 25 and 35°C. The lower temperature threshold for the embryonic development was around 16°C and the cumulative degree-days to complete development were estimated between 107.5 and 120.5°C.d. The optimum temperature for A. platae would be 25–30°C. Temperatures of 35°C and above would be harmful, while temperatures below 20°C resulted in rapid decreasing in activity and slower growth rates. The information about the thermal requirements of A. platae will be useful optimizing rearing conditions and developing predictive models of the potential distribution of A. platae in scenarios where it is introduced outside of its native range.

Apple snails (Ampullariidae) are among the largest and most ecologically important freshwater snails. The introduction of multiple species has reinvigorated the field and spurred a burgeoning body of research since the early 1990s, particularly regarding two species introduced to Asian wetlands and elsewhere, where they have become serious agricultural pests. This review places these recent advances in the context of previous work, across diverse fields ranging from phylogenetics and biogeography through ecology and developmental biology, and the more applied areas of environmental health and human disease. The review does not deal with the role of ampullariids as pests, nor their control and management, as this has been substantially reviewed elsewhere. Despite this large and diverse body of research, significant gaps in knowledge of these important snails remain, particularly in a comparative framework. The great majority of the work to date concerns a single species, Pomacea canaliculata, which we see as having the potential to become a model organism in a wide range of fields. However, additional comparative data are essential for understanding this diverse and potentially informative group. With the rapid advances in genomic technologies, many questions, seemingly intractable two decades ago, can be addressed, and ampullariids will provide valuable insights to our understanding across diverse fields in integrative biology.

The large arionid slug Arion vulgaris is an invasive pest dispersing through large parts of Europe and causing considerable damage in gardens, horticulture and agriculture. It is also possible that this so-called “Iberian slug” has an impact on Norwegian ecosystems, displacing or hybridizing with the native black slug Arion ater. The taxonomy of the large arionids is complex and confusing, encompassing different anatomical forms and colour varieties. The present study integrates, for the first time, coloration, ligula morphology, genital morphometry, nuclear and mitochondrial DNA in order to differentiate the large arionids found in Norway, A. vulgaris, A. ater and A. rufus. These data revealed a clear separation between A. vulgaris and A. ater based on the morphology of the genitalia and mtDNA. However, introgression with the red slug A. rufus was apparent in approximately half of the A. ater specimens analysed, evidenced by ligula morphology, mitochondrial and nuclear DNA. In addition, the mitochondrial COI gene and the nuclear ITS1 gene suggested introgression between A. ater and A. vulgaris. Phylogenetic analyses that included A. vulgaris, A. ater and A. rufus from other parts of Europe, together with A. flagellus, A. fuscus, A. lusitanicus and A. nobrei suggest that A. vulgaris is more closely related to A. ater and A. rufus than to A. lusitanicus. This study confirms the uncertainty of identification based solely on coloration and stresses the importance of integrating several approaches to differentiate these large arionids, allowing a better appreciation of their invasive potential, ecological impact and current distribution.

Radular ontogenies of four species of the neogastropod family Muricidae are described through comparisons of early post-metamorphic and adult developmental stages, with specific focus on the rachidian (central) tooth. The degree of rachidian transformation during ontogeny varies from minor shape change to addition or loss of structural features important for assigning taxa to subfamilies. Changes include: flattening of the rachidian base and a switch from a short, beak-like to a long, flattened central cusp in the rapanine Stramonita biserialis; a switch from variable, asymmetric to regular, symmetric expression of inner lateral denticles in the basal muricid Timbellus phyllopterus; curvature of the rachidian base at the margins and separation of the pointed base endpoint from the radular membrane to form a marginal cusp in the muricine Chicoreus dilectus; and moderate straightening of the rachidian base in the ocenebrine Vokesinotus perrugatus. From these observations and previous work, we propose a plesiomorphic developmental sequence for the Muricidae and provide supporting evidence for the developmental origins of novel features of the muricid radula.

Intracapsular embryonic development is common in marine gastropods. In many species, embryos obtain nutrition during ontogeny by ingesting substances contained in the intracapsular fluid. South American volutids spawn egg capsules containing relatively few eggs, and development is entirely intracapsular, with young hatching as crawl-away juveniles. The spawning habits, egg capsules morphology and embryonic development of the South American volutid Adelomelon ancilla is described in this work. Egg capsules of A. ancilla (n = 42) contained 3.0 ± 1.4 (mean ± SD) embryos with a range of 1–6 eggs or embryos. The embryonic morphological changes and body spiralization occur simultaneously with embryo feeding. All embryos within a single egg capsule shared the same developmental stage. No evidence of cannibalism or intracapsular competition was found, suggesting that food is not a limiting resource as in other volutid species. Estimated intracapsular developmental time varied between five and six months (between 12–14°C). The long developmental time and low number of embryos inside the egg capsules, together with late reproductive maturity and longevity of adult individuals, reinforce the statement that the neogastropod Adelomelon ancilla is a fragile resource that must be conserved in Argentinean benthic communities.

A new species of bivalve belonging to the family Vesicomyidae, Laubiericoncha puertodeseadoi, n. sp., is described. The material was collected during several cruises to the continental margin of Argentina on board of the R/V “Puerto Deseado”. The distribution of the genus Laubiericoncha is expanded to include the southwestern Atlantic Ocean. The description was done by using morphological characters of the shell and mantle cavity organs. All type material of congeneric species was examined and illustrated. Laubiericoncha puertodeseadoi, n. sp., is characterized by a compressed, subrectangular, elongated, inequilateral shell, with slightly prosogyrous umbo and a well-defined triangular pallial sinus, strong external ligament and ctenidia with two robust demibranchs, foot anteriorly projecting and fused siphons. This new species constitutes the first record of the genus Laubiericoncha living on the continental margin off Argentina.