The taxonomic history of Nautilus pompilius Linnaeus, 1758, the most widely distributed species of Nautilus Linnaeus, 1758, is complex, mostly owing to the antiquity of the earliest description by the naturalist Rumphius (Rumpf) in 1705. His account of its habits and illustrations of soft anatomy of specimens from Ambon, Molucca Islands, Indonesia were cited by Linnaeus in his description of N. pompilius. Nevertheless, there is almost no information on Nautilus in Indonesia. Live-caught animals (n = 44) from 150–400 m depth off Ambon provide the first morphologic and genetic details on Nautilus pompilius from the type region, including a recently proposed neotype for the type species. An additional sample (n = 62) obtained from the Sumbawa-Lombok Islands area, Indonesia, 1,500km to the southeast appears identical to those from Ambon. These populations have the largest known mature shells (mean ∼198mm diameter, ∼1,160 g shell plus body weight) of any of the numerous Indo-Pacific occurrences of Nautilus pompilius s.l. presently assigned to this species. Aside from size, few major phenotypic aspects differ from other populations of the species throughout its broad Indo-Pacific range. Data from two mitochondrial DNA gene regions identified a strongly supported clade comprising Ambon, Sumbawa, and Philippines N. pompilius s.s. These new data provide a baseline for evaluating genetic, phenotypic and geographic variation in the broadly distributed species N. pompilius s.l., as well as for establishing taxonomic relationships in populations of living Nautilus, including N. pompilius pompilius Linnaeus, 1758.

The Indo-West Pacific montacutid Curvemysella paula(A. Adams, 1856) is the sole representative of its genus and the only known bivalve that is an obligate commensal of hermit crabs. As such, studies on it are accordingly very few. It lives in small groups byssally attached to the internal columella of the host's adopted shell. This paper describes the species from a wave-exposed beach in central Vietnam at Danang. Here, it was living with Diogenes goniochirus, but elsewhere in Hong Kong and Japan other taxa serve as hosts. The adult shell of C. paula is antero-ventrally long, deeply concave ventrally and so inequivalve as to appear twisted. Smaller individuals are more equivalve and equilateral and become deformed with age and growth. The hinge plate has a structure typical of the Montacutidae with the ligament ventrally formed into a lithodesma. Anatomically, C. paula is also unremarkable and interest in it focuses on reproduction. The species lives in small groups, the oldest and largest being a female, the smallest and youngest males. Intermediate sized individuals are hermaphroditic. Curvemysella paula is thus a protandric consecutive hermaphrodite. Prodissoconch morphology suggests that C. paula does not ctenidially brood fertilised eggs or, if so, only briefly. Further, it seems likely that there is subsequently an abbreviated lecithotrophic period of development perhaps undertaken close to the sea bed - thereby keeping the larvae close to established hermit crab and parental bivalve populations.

The mussel Choromytilus chorus (Molina, 1782) is a commercially and ecologically important bivalve, which is extensively distributed along the Chilean coast (20°S–54°S). However, there are no previous studies regarding the reproductive aspects of this species in the northern part of its range. Mussels were collected at Caleta Errázuriz, along the Antofagasta coast (ca. 24°S), between December 2014 and June 2015. A total of 1620 individuals were examined using histological techniques and macroscopic visual inspection. Seventeen size categories, which included individuals from 5 mm to 100 mm in length, were analyzed. The size at the onset of sexual differentiation and the size at first sexual maturity (50% mature individuals) were determined. Males comprised 49% of the total sample, and 51% were females. Mussels from 5–22 mm in valve length were undifferentiated and from 22–24 mm were sexually differentiated. The size at first sexual maturity was recorded as 38–40 mm. In vitro fertilization trials demonstrated that sexually differentiated individuals were able to produce viable gametes. The biological parameters analyzed for C. chorus were similar to those recorded for populations of this bivalve from the southern latitudes. However, the lower number of eggs per female and the smaller egg size suggests that the population parameters may be different for C. chorus between the northern and southern latitudes.

Despite the existence of more than 565 islands in the upper three United States Great Lakes, land snails have been reported from only about 1% of them. This first publication about land snails of any island in eastern Lake Michigan reports on the 38 species (10,162 individuals) of land snails we found on South Fox Island. We examined leaf litter samples collected from 14 localities on South Fox Island in the years 1993 and 1997. We provide identification notes and habitat notes (beech-maple forest, cedar forest, meadow) for each of the species. The number of species, 38, on South Fox Island is about average when compared to the number of species from six other islands in the upper three Great Lakes that have had comparable sampling intensity. We report the northernmost published localities for two minute snails, Carychium nannodes G.H. Clapp, 1905 and Striatura meridionalis (Pilsbry and Ferriss, 1906), and one of the northernmost localities for the minute snail Guppya sterkii (Dall, 1888). The absence of two larger species that are present on the adjacent mainland is consistent with our hypothesis that the sequences of glacial history, island development, and northward snail colonization have influenced modern distributions of snails.

The genus Pyropelta McLean & Haszprunar, 1987 is exclusively restricted to deep-sea chemosynthesis-based environments, that range from the Western and Eastern Pacific to West Africa. In the present study, a new species, Pyropelta elongata sp. nov., collected from a methane seep area in South China Sea is described and illustrated. The generic assignation is mainly based on shell and radula characters. Pyropelta elongata sp. nov. is characterized by relatively large, elongate shell with a low profile and has a radula formula of (ca. 20) 5 1 5 (ca. 20). These features can distinguish the new species from other congeners.

The gastropod Cassis tuberosa (Linnaeus, 1758) usually lives in and on soft sediments and sea grass meadows. This carnivorous snail is primarily a semi-epifaunal and nocturnal hunter that, during daytime, rests burrowed in sediments. Around the Bahamian island of San Salvador, C. tuberosa has extended its behavior from nocturnal to metaturnal; feeding both night and day. This modification also involves further changes in behavior as an individual was observed resting epifaunally between rocks during the day even though this substrate was surrounded by soft bottoms. Epifaunal Cassis specimens are entirely encrusted primarily by coralline algae, but also by various green algae accompanied by vagile snails and crabs. The high degree of encrustation suggests that these snails do not remain burrowed for long periods of time. Cassis has thus extended its resting behavior from a semi-endofaunal to an epifaunal mode of life. The fouled shells also function as mobile benthic substrates for various organisms.

We are reporting the first locality of invasive giant African snail, Achatina (Lissachatina) fulica (Férussac, 1821) in the Ecuadorian Amazon. It was found present in 32 out of 50 urban sites studied. The abundance where present was relatively high when compared to literature from other parts of the world. The snails were found in aggregations, usually foraging — most often on dogs' feces. Statistical analysis suggests a preference toward this source of alimentation. This is the first report of such preference in this species, which is highly significant considering the possible implications. Besides the threat posed by an invasive species to the invaluable ecosystems of the Amazon, the pathogens transferred by A. fulica combined with a high abundance of the species in an urban environment and its food preferences may constitute an important health hazard for local human populations.

The invasive New Zealand mud snail, Potamopyrgus antipodarum (Gray 1843), has been present in the Laurentian Great Lakes for at least 20 years. Recently, the snail has spread to streams that empty into Lake Ontario. In the deep waters of Lake Ontario, detritus is the common food source for the snails; while in streams periphyton becomes an important part of their diet. This experiment was designed to test the hypothesis that a diet of periphyton will lead to a higher growth rate compared to detritus. Benthic sediment was collected from 18 m depth in Lake Erie. Periphyton was grown on small rocks collected from Spring Run stream in central Pennsylvania. Eighty juvenile snails (0.6–1.0 mm in length) were placed individually into plastic cups and divided into four treatments: control snails that were fed Spirulina powder (standard lab diet), snails kept in lake sediment, snails reared on rocks with periphyton growth, and snails in a combination habitat of rock and lake sediment. After six weeks, the snails were measured again. Snails in the periphyton-only treatment had a significantly greater growth rate than snails in the remaining treatments. The other three treatments resulted in similarly low growth rates. These results suggest that the change in diet from detritus-based to periphyton-based as the snails move from a lake to a stream environment may result in higher individual and possibly population growth rates, and thus could increase their invasion success.

Cladobranchia is a diverse clade of nudibranch gastropods, with ∼1,000 coastal (benthic) and off shore (pelagic) marine species. Their diversity may be tied to dietary specialization and the evolution of remarkable adaptations that are rare among animals, such as the sequestration of cnidarian nematocysts. Due to the deep divergences within Cladobranchia, and other higher-order taxa within Mollusca, phylogenetic analyses based on morphology or a few genes have been unable to resolve relationships within these clades with high support. The introduction of high-throughput sequencing technologies, however, has provided the opportunity to collect large genomic data sets, which have proven useful in resolving relationships within molluscs, as in other metazoan groups. As sequencing costs decrease, it has become easier to collect ever larger data sets in an attempt to resolve relationships within more recently diverged groups, such as Cladobranchia. The phyly and relationships of the three main groups within Cladobranchia (Arminida, Dendronotida, and Aeolidida) have been difficult to determine, primarily due to the rapid evolution of mtDNA and rDNA genes analyzed in traditional molecular phylogenetic studies. In this review, I discuss the systematics of Cladobranchia in regards to morphological data, molecular analyses with one or a few genes, and address the impact of genomic data. I then contend that the supported phylogenetic hypotheses provided by high-throughput sequencing data will provide a better framework for studying taxonomy and character evolution within Cladobranchia, as these data provide strong support for Cladobranchia itself, as well as the nested subclades within it. Although it is important to note that a broader taxon sampling is still needed for genomic data, it is clear that utilizing these data has provided the most-well-supported phylogenetic hypotheses of Cladobranchia to date. In doing so, these genomic data have challenged well-established relationships, including the monophyly of Facelinidae and inclusion of Tritoniidae in Dendronotida, and resolved the position of taxa that have been traditionally quite difficult to place, including Melibe Rang, 1829 and the families Proctonotidae and Dironidae. Finally, these genomic data provide a much stronger phylogenetic framework for studying character evolution within Cladobranchia, including the evolution of nematocyst sequestration, one of the quintessential characters in this clade.