Life-history traits in terrestrial gastropods may be influenced by both abiotic and biotic factors. This study examines the effects of soil type and adult size (shell volume) on mating propensity and female and male reproductive output (number and mass of eggs, number of sperm delivered and spermatophore mass) in individuals of the simultaneous hermaphrodite land snail Arianta arbustorum from two populations kept both on calcium-(Ca-)rich and Ca-poor soil. Snails from the two populations differed in adult size, relative shell growth, mating propensity and egg size. Furthermore, in both populations the number of egg batches deposited, egg size and spermatophore size scaled allometrically with shell volume, but not the total number of eggs produced and number of sperm delivered. Independent of population and shell size, the type of soil on which the snails were maintained influenced mating propensity, the total number of eggs produced and the mass of the albumen gland (another measure of female reproductive output). The mating propensity was higher and the total number of eggs produced was larger in snails kept on Ca-poor soil than in individuals reared on Ca-rich soil. This surprising finding could be explained by the fact that the Ca-poor soil used in the experiment still contained enough Ca to allow reproduction, and that the snails ingested Ca through the food consumed (lettuce grown on Ca-rich soil was available ad libitum). Moreover, the Ca-rich soil could contain minerals or (unknown) substances which discourage reproduction in A. arbustorum. Our study highlights the complexities faced when interpreting differences in the life history of gastropods. Explaining interpopulational differences in life-history patterns requires not only the understanding of the influence of snail origin, but also an understanding of the effects of shell size, substratum type (soil type), food and local climate.

Among the many octopods collected during recent Antarctic trawling surveys were 93 specimens of an undescribed octopod with biserial suckers. Although most similar in appearance to the sub-Antarctic Benthoctopus levis (Hoyle 1885), these octopods differed in several morphological characters, including arm length, web depth, and details of the hectocotylus. Furthermore, molecular evidence supports the separation of the present material from known species. We therefore describe a new species named Benthoctopus rigbyae. These octopods attain mantle lengths of at least 105 mm (400 mm total length), and they are common at depths of 250–600 m throughout the South Shetland Island chain off the Antarctic Peninsula. We present some information on the biology of this species.

Life histories and population dynamics of two populations of Musculium argentinum, one inhabiting a fluvial environment and the other a lacustrine one, are compared. Musculium argentinum is oviparous, iteroparous, and sequential incubator, reproducing throughout the year. The life cycle pattern of the fluvial population, unlike the lacustrine one, is characterized by seasonal reproductive variations, more marked in spring and summer, higher fertility and population reproductive productivity (potential recruitment), higher number of marsupial sacs per hemibranch, and smaller size of first reproduction. The content of organic matter and water flow would be the main factors determining the higher population density observed in the fluvial population.

Wilhelm Dunker was the foremost expert on the systematics of the bivalve family Pteriidae (referred to as genus Avicula in his time) in the nineteenth century. His work on the group culminated in the monograph Die Gattung Avicula, a part of the significant conchological iconography, Systematisches Conchylien-Cabinet (Küster et al., 1837–1920). Dunker's volume remains unsurpassed in the taxonomic scope and the quality of illustrations. However, despite the fact that Die Gattung Avicula was readily available and widely cited, few specialists consulted the actual type material from the Dunker collection, which fell into oblivion for over a century. In this work, we attempted to reconstruct the contents and the history of Dunker's collection of pteriid bivalves, the specimens of which derive from two principal repositories, the Museum für Naturkunde in Berlin and the Aquazoo-Löbbecke Museum in Düsseldorf. In addition to the annotated catalog of type and figured specimens, many of which are here recognized for the first time, this contribution gives an account of Dunker's life and science, and provides an overview of pertinent contemporary shell collections.

We studied the frequencies of shell-banding variants of Cepaea vindobonensis (Férussac) in open, semi-open and shaded habitats in two geographically separate but climatically similar areas in southeastern Poland. The faint-banded phenotype was more frequent in open and semi-open habitats than in shaded areas. Within the dark-banded phenotype, those with missing bands were associated with open and semi-open habitats, and those with fusion of bands with shaded habitats. The feature most strongly associated with habitat type was the width of bands relative to the ground area. It was significantly higher in shaded habitats than in semiopen areas, in which it was significantly higher than in open habitats. Our study thus indicated the effect of local microclimatic selection on the frequencies of various phenotypes, resulting in light shells being more common in open habitats and dark shells in shaded areas. This association of shell characteristics with habitat type was more pronounced in the area where Cepaea vindobonensis inhabited more natural habitats and showed higher polymorphism.

Species restricted to the higher altitudes of low mountain ranges in Central Europe are among the species threatened. To quantify the influence of climate warming, we analysed the altitudinal distribution of mollusc species and modelled the occurrence and distribution of a high montane species under two scenarios of climate warming. Our analysis is based on samples of 3,437 individuals and 46 species collected at 111 localities. Number of individuals and species decreased with altitude. The slope of this decrease changed between 1,100 and 1,200 m a.s.l., which is the ecotone between mixed montane beech-fir-spruce and high-altitude spruce forests. In contrast to the majority of species and the number of species, the occurrence of Semilimax kotulae (Westerlund 1883), a Central European endemic, increased with altitude. Again, we found a change in the slope between 1,100 and 1,200 m a.s.l. Using geostatistical models of local temperature as well as spatial GLMs with Poisson and Gaussian errors, we modelled altitudinal distribution of diversity and species under consideration of environmental variables. Especially habitat age was an important predictor for the abundance of many species. For the high montane species S. kotulae, our model predicts a decrease in occurrence and abundance with global warming. Although global warming will lead to an overall increase in number of species, species occurring only at higher elevations, such as the S. kotulae, will probably become extinct within the study area.

The chromosome complement and the nuclear DNA content in two caenogastropod species from the Mediterranean Sea, Crepidula unguiformis (Calyptraeidae) and Naticarius stercusmuscarum (Naticidae), were investigated by the application of both classical and molecular cytogenetic methods. Despite the constancy of haploid chromosome numbers (n = 17 in both species), C. unguiformis and N. stercusmuscarum show genome sizes amounting to 6.36 and 2.63 pg, respectively. Moreover, while N. stercusmuscarum resembles cytogenetically the other neotaenioglossan caenogastropods studied so far, C. unguiformis differs in: (i) number and location of rDNA clusters (ii), composition of telomeric repeats, and (iii) genome size, thus suggesting a peculiar karyotypical evolution undergone by this species.

Gonadosomatic index (GSI), annual reproductive cycle, monthly changes in oocyte sizefrequency distributions, size at first sexual maturity and sex ratio of the sun and moon scallop, Amusium japonicum japonicum, were investigated. Samples were collected monthly from the subtidal zone of Sogwipo, Jejudo, Korea.

Amusium japonicum japonicum is dioecious. The ovary is composed of a number of oogenic follicles, and the testis consists of a number of acini. Monthly variation in the GSI showed a pattern similar to that of the annual reproductive cycle. Ripe oocytes were about 70–90 µ in diameter. The spawning period was from November to January, and the main spawning occurred between December and January when the seawater temperature was relatively low. The annual reproductive cycle of this species can be classified into five successive stages: early active stage (April to June), late active stage (June to September), ripe stage (October to November), spawning stage (November to January), and spent / resting stage (February to April). The spawning period occurred once per year.

The percentage of first sexual maturity of female and male scallops ranging in length from 85.1 to 90.0 mm was over 50% and 100% for scallops over 90.0 mm length. In the population under study, sexually mature female and male shell lengths (50% of sexual maturity) were 86.96 and 86.59 mm respectively.

The sex ratio of individuals over 85.1 mm length was not significantly different from 1:1 (x2 = 0.18, p > 0.05). No hermaphrodites were found.

As part on an ongoing effort to unravel the taxonomy and phylogeny of Palaearctic freshwater mussels, this paper describes an overlooked Unio species that inhabits the Atlantic rivers of South Iberia and Morocco, based on morphological, reproductive, and molecular characters. Live specimens of Unio gibbus were recently found in the Barbate River in southwest Spain and in the Beth River in the Sebou basin, northwest Morocco.

Phylogenetic relationships inferred from partial COI and 16S rRNA gene sequences point to the recognition of U. gibbus as an evolutionary unit. Genetic divergences with respect to other Unio species ranged from 10.24% and 6.18% (compared to U. tumidus) to 12.91% and 8.89% (compared to U. tumidiformis) for COI and 16S rRNA respectively.

In the Spanish specimens, the entire internal cavity of the external demibranchs (homogeneity) acts as a marsupium (ectobranchy), yet in the Moroccan population, the four gills are occasionally filled with glochidia (occasional tetrageny). Glochidia are rounded triangular, intermediate between the shapes of those in other species of Unio and Potomida. The border of the larval shell bears numerous small lumps, but these fail to form the ventral styliform hook typical of the genus Unio. These two characters, tetrageny and hookless glochidia, both of major significance in phylogenetic studies of the group, are reported here for the first time in the genus Unio.

The Spanish populations of U. gibbus should be a main priority for European invertebrate conservation measures.

Female octopuses are thought to copulate with multiple males and store sperm for months prior to spawning, a generalization that has led to hypotheses of strong sperm competition throughout the family. Their diversity, and the difficulty in observing many octopus species in the wild, force indirect tests of this generalization. Male reproductive effort, already high in these generally semelparous animals, is predicted to increase further with sperm competition. Hypothesized functional constraints on the spermatophores that males build to transfer sperm could mean that selection impacts spermatophore number more than morphology. To test whether the number of spermatophores could indicate differences in octopodid biology, the greatest number of spermatophores carried by one individual, and longest spermatophore and mantle lengths were compiled for 74 species. Differences in number were predicted to be independent of differences in specimen availability, related species were predicted to have similar counts, and counts were predicted to be largely independent of spermatophore and mantle length. The median spermatophore count was 24; nearly one-third of the species had 60 or more spermatophores. Of these, 16 were species of Eledone, Octopus (Octopus) or Abdopus, supporting the hypothesis that related species share similar spermatophore counts; relationships of the other species are poorly known. Spermatophores of these 24 species tended to be slightly shorter relative to mantle length than in the family as a whole. Callistoctopus spp. carry nine or fewer spermatophores, as do deep-sea species of Bathypolypus, and the Southern Ocean endemic and deep-sea octopus clade. The number of specimens did not differ between species with fewer or more than the median number. Differences in spermatophore counts among species may offer insight into male response to sperm competition and the unsuspected diversity of reproductive behavior in benthic octopods.