Cirrate octopods are considered to resemble the ancestor of all octopuses. Cirrates inhabit the deep ocean and are characterized by the presence of fins, a cartilaginous inner shell and a single row of suckers alternating with pairs of cirri thus comprising uniserial suckers and biserial cirri. The objective of this contribution is to improve the taxonomy of Opisthoteuthis bruuni from the southeastern Pacific Ocean and to suggest a new hypothesis of cirrate phylogeny. Given that the most complete molecular data set for cirrates available in public databases is comprised almost exclusively of 16S rRNA gene sequences, we compared the morphological and mitochondrial gene 16S rRNA data generated in this study from the genus Opisthoteuthis from the southeastern Pacific Ocean. Additionally, we sequenced Opisthoteuthis chathamensis, Opisthoteuthis mero and Luteuthis dentatus from the southwestern Pacific, as along with Cirroctopus mawsoni from Antarctic waters. The morphological data and the phylogenetic analysis confirm the status of Opisthoteuthis bruuni as a member of genus Opisthoteuthis and the family Opisthoteuthidae. This re-description includes the first morphological characterization of the male and female adult stage of O. bruuni, in addition to reporting geographic and bathymetric range extensions. Opisthoteuthis bruuni presents conspicuous morphological features (small terminal fins, short cirri and U-shaped shell). Our phylogenetic tree supports three families: Cirroctopodidae, Cirroteuthidae and Opisthoteuthidae, which is different from the phylogenetic arrangements previously reported.

The poisonous eggs of Pomacea canaliculata hardly have any predators. This invasive snail, listed among 100 of the worst invasive species, is a serious crop pest and a vector of human parasitic diseases. Females lay eggs in pink-reddish masses, the colour presumably a warning of their chemical defenses. Egg ingestion alters rodent gastrointestinal tracts and is lethal if injected, but its effect on other taxa is unknown. Here we explored the toxic effects of Pomacea canaliculata eggs on the bullfrog Lithobathes catesbeianus (Anura, Ranidae).

Juvenile bullfrogs were gavaged with egg extracts and their digestive tract analyzed after 24 h and 48 h using histological, immunohistochemical and lectin-histochemical techniques. Toxicity was also evaluated by intraperitoneal injection of egg extract.

Egg extract ingestion adversely affected the small intestine of the bullfrogs. Short term (24 h) effects included large, reversible changes of the intestinal wall, villi morphology, and changes in the glycosylation patterns of enterocytes. The mucosal area increased and infiltration of inflammatory cells, mainly eosinophils and macrophages, were observed together with a weak hemorrhage. Most of these changes reversed after 48 h. In addition, intraperitoneal injection of egg extract was nontoxic to bullfrog juveniles and no lethality or behavioral changes were observed, a remarkable difference from the effect on rodents.

Overall, these results indicate that toxins of apple snail eggs reversibly modify gut morphology, which may alter bullfrog physiology, limiting their ability to absorb egg nutrients. This study extends the known targets of the apple snail egg defenses against predation to amphibians.

The morphological plasticity of bivalve species may impair their correct identification. Pisidium species (Sphaeriidae) are difficult to distinguish, notably the common pea clam, Pisidium casertanum (Poli, 1791), which is a polymorphic species, often misidentified and confused with other Pisidium species. This is especially true since this species is the most euryecious of the genus, being able to colonize very different habitats. In this study, elliptic Fourier Analysis, a geometric morphometric method, was used to assess intraspecific variation in P. casertanum. Sampling of specimens was done in three habitat types – springs, lakes and streams – in the Mediterranean biodiversity hotspot region, using the Sebou basin in Morocco as a study area. In addition to the geometric morphometric method, linear measurements of the shell were used to assess growth patterns. Results revealed differences in the hinge plate, which is broader in shells collected from lakes, whereas it is higher in shells of springs. The geometric morphometric method clearly showed shape differences between individuals of the three habitats. Specimens of lakes were the most distinguishable, presenting more elongated shells than those from springs and streams, which are shorter but higher. Individuals from the three habitat types presented a negative allometric growth pattern whereby the shell of animals grows more slowly in height than in length. The use of linear and geometric morphometric methods led to conclude that the morphology of P. casertanum is, in fact, highly influenced by its environment, in particular, its habitat type.

The species belonging to the family Mactridae living in South African waters are revised. After a bibliographical research, almost forty nominal species were found related to this area. The type material of all taxa was requested, examined and illustrated whenever possible. Additional comparative specimens from Natal Museum were studied. Details of type localities, repositories, and updated distribution were provided. This work revealed the presence of nine species belonging to the family Mactridae living in South African waters: Mactra aequisulcata G. B. Sowerby III, 1894, Mactra lilaceaLamarck, 1818, Simomactra capensis (G. B. Sowerby III, 1892), Scissodesma spengleri (Linnaeus, 1767), Standella ovalina (Lamarck, 1818), Lutraria (Lutraria) capensisReeve, 1854, Lutraria (Lutraria) steynlussii Huber, 2010, Lutraria (Psammophila) inhacaensisBoshoff, 1965, and Eastonia solanderi (Gray, 1837). However, their generic placement in some cases must be confirmed. Genetic data will clarify if two new generic names for Mactra aequisulcata and Simomactra capensis, respectively, are required.

Current knowledge on the pyramidellids from the southern tip of South America appears restricted to a couple of species described in the beginning of the 20^th century and a few taxa subsequently reported from this area, including some species recognized as new, but never formally described. This study fills this gap in the knowledge by performing the first revision on the diversity of Pyramidellidae occurring in the Magellanic Province. The material for this study arises from extant collections made along the Atlantic and Pacific coasts of Patagonia, the Beagle Channel, the Magellan Strait and in Burdwood Bank; this information was supplied with specimens from museum collections. As part of this study, eight pyramidellid species, belonging to the genera Turbonilla, Fargoa, Menestho and Brachystomia are recognized from the Magellanic Province, including five species new to science: Turbonilla deseadensis n. sp., Menestho beaglensis n. sp., M. patagonica n. sp., Brachystomia conica n. sp. and B. tenuilirata n. sp. The distinctive characters of Menestho, a genus frequently misunderstood in the past, are also discussed. The presence of Menestho and Brachystomia are here documented for the first time for the southern tip of South America. In addition, a neotype for Turbonilla strebeliStrebel, 1905 (nonVerrill, 1880) is here designated.

Using analytical (Raman spectroscopy) and imaging (scanning electron microscopy) approaches, we evidenced a biogenic mineralization process in the pedal mucus of the vermetids Eualetes tulipa and Petaloconchus varians. Raman spectra showed the presence of main bands around v₁(CO) 1,085, n₄(OCO) 717 and 705 cm^-1 attributed to stretching modes of calcium carbonate crystallized as calcite and aragonite. SEM images showed the presence of aragonite needles and rhombohedral crystals of calcite in the mucus. Secondary nucleation from calcium carbonate precursors is the most probably pathway for the formation and growth of calcium carbonate crystals in feeding mucus of E. tulipa and P. varians. The tube-like shells of vermetids are very plastic. They are capable of continuously modify the direction of the shell aperture, remolding their tubes and building terminal structures. As a result, vermetid shells may act as exploratory tubes that allow the snail to profit from a better water flow, avoid obstacles and successfully compete for space. Such plasticity probably demands an extra supply of calcium carbonate, particularly when indeterminate growth is involved, as is the case for species of Eualetes and Petaloconchus; this would explain the functional significance of the biogenic calcium carbonate formation in the feeding mucus.

The genus PseudiberusAncey, 1887, in Shandong, China, distributed in the mid to the south mountainous areas of the province, represents the largest terrestrial mollusks in this region. By molecular phylogenetic inference and genetic distance comparison based on ITS2 + 16S sequences, P. tectumsinense tectumsinense (Martens, 1873), P. tectumsinense zenonis (Gredler, 1882), P. tectumsinense anderssoni (Odhner, 1925) and P. tectumsinense depressus (Yen, 1935), are confirmed to be subspecies under P. tectumsinense (Martens, 1873). Pseudiberus tectumsinense pingi, new subspecies, is proposed to be new based on shell morphology, anatomy, and evidence of molecular phylogeny. Pseudiberus futtereri (Andreae, 1900) is removed from the species list of Shandongese Pseudiberus. The proximal accessory sac, observed in all the anatomically known Pseudiberus from Shandong, is described for the first time in dart sac apparatus from the bradybaenine snails. The variations and patterns of the proximal accessory sac among Pseudiberus tectumsinense subspecies and P. chentingensis distributed east to the Taihangshan Mountain Chain are examined. The close relationship among Shandong's Pseudiberus might be indicative of their rather recent evolutionary divergence, which was possibly driven by allopatric isolation of populations confined to refugial habitats like isolated mountain tops surrounded by extensive flood plains.

Many mollusks host symbiotic microbiota that are tightly involved in molluscan biological functions and ecological interactions. Here, we review the described symbioses between molluscan hosts and their bacterial partners. We focus on associations where the molluscan host is hypothesized to gain an evolutionary advantage because of the role of its symbiont. In addition, we focus only on those relationships that have been established experimentally or at least show strong evidence for symbioses. Along with providing a review of the known molluscan host/microbe mutualistic symbioses, we also outline common methodologies in the study of these relationships. Last, we point out areas of further exploration for molluscan microbiome studies.

We report an introduction of the predatory land snail Poiretia delesserti (Bourguignat, 1852) (Spiraxidae) from Albania and Greece in Cagnes-sur-Mer in southeastern France discovered by a citizen scientist. An uncontrolled expansion of this species in this region, which is characterized by a high number of endemic land snail species, is likely to result in extinctions. Therefore, we recommend the nature conservation authorities to survey the site to quantify population density and extent and to eradicate the introduced population of P. delesserti via manual collection.