The molecular phylogeny of Caenogastropoda (Mollusca, Gastropoda) based on mitochondrial genomes and nuclear genes

Comprising about 60 % of gastropod diversity, caenogastropods display almost all kinds of shell forms and include many commercially important marine groups. Although the monophyly of Caenogastropoda has been widely accepted, thier internal phylogenetic relationships remain unclear. In the present study, a total of 27 caenogastropods belonging to eight superfamilies were sequenced and used for phylogenetic reconstruction. All newly sequenced mitogenomes adhered to the consensus gene order of caenogastropods, except for those of Vanikoroidea, Vermetoidea and Cerithioidea, which involved protein-coding genes. The reconstructed mitogenomic phylogeny suggested the monophylies of Architaenioglossa, Sorbeoconcha, Hypsogastropoda and the siphonate clade. The present study also identified a close affinity among Cypraeoidea, Ficoidea, Tonnoidea, and Neogastropoda, supported by the presence of a pleurembolic proboscis. The monophyly of Neogastropoda was not supported, as Cancellariidae was found to be sister to the limpet-shaped group Calyptraeoidea, and (Tonooidea + Ficoidea) were sister to the remaining neogastropods. This study provides important information for better understanding the evolution of caenogastropods, as well as for the protection and utilization of these diverse and economically significant marine resources.

The temperate marine Peruvian Province: How history accounts for its unusual biota

The Peruvian Province, from 6° S in Peru to 42° S in Chile, is a highly productive coastal marine region whose biology and fossil record have long been studied separately but never integrated. To understand how past events and conditions affected today's species composition and interactions, we examined the role of extinction, colonization, geologic changes to explain previously unrecognized peculiar features of the biota and to compare the Peruvian Province's history to that of other climatically similar temperate coasts. We synthesized all available data on the benthic (or benthically feeding) biota, with emphasis on fossilizable taxa, for the interval from the Miocene (23-5.4 Ma) and Pliocene (5.4-2.5 Ma) to the present. We outline the history of ecological guilds including primary producers, herbivores, predators, and suspension-feeders and document patterns of extinction, colonization, and geographic restriction. We identify twelve unusual attributes of the biota, most of which are the result of repeated episodes of extinction. Several guilds present during the Miocene and Pliocene are not represented in the province today, while groups such as kelps and perhaps intertidal predatory sea stars are relative newcomers. Guilds on soft bottoms and in sheltered habitats were severely affected by extinction, whereas those on hard bottoms were most affected by colonists and held their own in diversity. The Peruvian Province has not served as a biogeographic refuge, in contrast to the coasts of Australasia and Argentina, where lineages no longer present in the Peruvian Province survive. The loss of sheltered habitats since the Pliocene explains many of the present-day peculiarities of the biota. The history of the province's biota explains its unique attributes. High productivity, a rich Southern Hemisphere heritage, and colonization from the north account for the present-day composition and unusual characteristics of the biota.

Phylogenomics of Neogastropoda: the backbone hidden in the bush

The molluscan order Neogastropoda encompasses over 15,000 almost exclusively marine species playing important roles in benthic communities and in the economies of coastal countries. Neogastropoda underwent intensive cladogenesis in early stages of diversification, generating a 'bush' at the base of their evolutionary tree, that has been hard to resolve even with high throughput molecular data. In the present study to resolve the bush, we use a variety of phylogenetic inference methods and a comprehensive exon capture dataset of 1,817 loci (79.6% data occupancy) comprising 112 taxa of 48 out of 60 Neogastropoda families. Our results show consistent topologies and high support in all analyses at (super)family level, supporting monophyly of Muricoidea, Mitroidea, Conoidea, and, with some reservations, Olivoidea and Buccinoidea. Volutoidea and Turbinelloidea as currently circumscribed are clearly paraphyletic. Despite our analyses consistently resolving most backbone nodes, three prove problematic: First, uncertain placement of Cancellariidae, as the sister group to either a Ficoidea-Tonnoidea clade, or to the rest of Neogastropoda, leaves monophyly of Neogastropoda unresolved. Second, relationships are contradictory at the base of the major 'core Neogastropoda' grouping. Third, coalescence-based analyses reject monophyly of the Buccinoidea in relation to Vasidae. We analysed phylogenetic signal of targeted loci in relation to potential biases, and we propose most probable resolutions in the latter two recalcitrant nodes. The uncertain placement of Cancellariidae may be explained by orthology violations due to differential paralog loss shortly after the whole genome duplication, which should be resolved with a curated set of longer loci.

Systematics and Distributions of Upper Bathyal Species in Bathyancistrolepis, a Deep-Sea Whelk Genus Endemic to the Northwest Pacific (Gastropoda: Buccinidae)

The deep-sea buccinid snail genus Bathyancistrolepis is redefined based on the reconstruction of a molecular phylogeny and morphological examination of shell and radular characters. This genus is distinguished from other genera of the subfamily Parancistrolepidinae with a combination of shell traits, including (1) a low spire, (2) sharp, carinate spiral cords or keels and (3) a long, curved siphonal canal, but not with a difference in radular morphology as suggested by previous authors. Three allopatric or parapatric species are recognized in the upper bathyal (447-2057 m) waters around Japan and Taiwan: B. tokoyodaensis from off Hokkaido to Sagami Bay in the Northwest Pacific, B. trochoidea off Kumano-nada to Miyazaki in the Northwest Pacific and along Nansei Islands in the East China Sea, and B. taiwanensis sp. nov. in the South China Sea. These species bear large paucispiral protoconchs that are indicative of benthic early development without a pelagic larval period, and hence low dispersal capability. Seafloor topography seems to have acted as a barrier for their dispersal; the range of B. tokoyodaensis supports the previous finding that Izu Peninsula delimits westward distribution of bathyal gastropod species of boreal origins.

Seven new genera and thirty-four new species of buccinoid gastropods (Neogastropoda: Buccinidae) from the Aleutian Islands, Alaska

Seven new genera and thirty-four new species of gastropods in the in the family Buccinidae, are described from the Aleutian Islands. The new taxa represent five subfamilies: Parancistrolepidinae Habe, 1972: Boreancistrolepis excelsus n. gen. & n. sp. Beringiinae Golikov & Starabogatov, 1975: Aleutijapelion mirandus n. gen. & n. sp.; Beringius nearensis n. sp., B. amliensis n. sp., B. bisulcatus n. sp., B. kiskensis n. sp., B. stanchfieldi n. sp., B. frausseni n. sp., B. aurulentus n. sp., B. maristempestus n. sp., B. undataformis n. sp.; Exiloberingius exiguus n. gen. & n. sp. Neptuneinae Stimpson, 1865: Aulacofusus canaliculatus n. sp., A. tanagaensis n. sp.; Neptunea aleutica n. sp., N. baxteri n. sp., N. dominator n. sp., N. petrelensis n. sp., N. quhmax n. sp., N. vesteraalen n. sp.; N. harrisoni n. sp., N. jewetti n. sp., Laevisipho galaxaios n. gen & n. sp., L. kessleri n. sp.; Volutopsiinae: Volutopsius nanus n. sp., Volutopsius gracilis n. sp.; Crebrivolutopsius labidentatus n. gen. & n. sp. Buccininae Rafinesque, 1815: Aleutibuccinum n. gen.; Castaneobuccinum orri n. gen. & n. sp., C. lauthi, n. sp., C. clinopsis n. sp., C. pagodaformis n. sp.; Sulcosinus carinatus n. sp.; Buccinum lanatum n. sp.; and Buccinum katharinae n. gen. & n. sp. The new genera and species are distinguished by the morphological characters of the shells and radulae.

Molecular phylogeny of Columbellidae (Gastropoda: Neogastropoda)

The neogastropod family Columbellidae is a highly successful group of small, primarily epibenthic marine snails distributed worldwide and most abundant in the tropics. The great diversity of the group makes them attractive for studying evolutionary shifts in gastropod anatomy, morphology, ecology and diversity. The existing classification of the family has been based to a large degree on the morphology of the shell and radula. Indeed, membership in the family is traditionally confirmed using the unique morphology of the radula. To reconstruct columbellid phylogeny and assess monophyly of the group, we assembled a multilocus dataset including five mitochondrial and nuclear genes, for 70 species in 31 genera. Phylogenetic analyses using Bayesian inference and maximum likelihood are not well enough resolved to support a subfamilial classification, but do support the monophyly of the family and of several well-defined genera and supra-generic groupings. Two of the most diverse nominal genera, Mitrella and Anachis, are supported as highly polyphyletic. Overall, the resulting topologies indicate that the generic and subfamilial classification is in need of extensive revision but that phylogenomic data are needed to resolve columbellid relationships.

A Comparative Analysis of Mucus Immunomodulatory Properties from Seven Marine Gastropods from the Mediterranean Sea

The treatment of inflammatory and immune-related diseases due to dysfunctioning of the immune system necessitates modulation of the immune response through immunomodulatory compounds. Marine environments are considered as a new frontier for health benefit product implementations. Marine biodiversity is still a low explored resource, despite it is expected to represent an important platform for chemical bioactive compounds. Within the phylum Mollusca, gastropods are known to synthetize mucus, the latter presenting relevant bioactive properties, e.g., related to immunomodulant molecules able to activate the innate and acquired immune system. This study proposes a bioprospecting of the immunomodulant activity of mucus isolated from seven common gastropod species from the Gulf of Naples (Mediterranean Sea). Results showed that not all mucus displayed a significant cytotoxic activity on the two human cancer cell lines A549 and A2058. On the other hand, the mucus from Bolinus brandaris was strongly bioactive and was therefore thoroughly investigated at cellular, molecular, and protein levels on the human monocytes U937 line. It can conclusively induce monocyte differentiation in vitro and significantly stimulate natural immunity response.

Neogastropod (Mollusca, Gastropoda) phylogeny: A step forward with mitogenomes

The Neogastropoda (Mollusca, Gastropoda) encompass more than 15,000 described species of marine predators, including several model organisms in toxinology, embryology and physiology. However, their phylogenetic relationships remain mostly unresolved and their classification unstable. We took advantage of the many mitogenomes published in GenBank to produce a new molecular phylogeny of the neogastropods. We completed the taxon sampling by using an in‐house bioinformatic pipeline to retrieve mitochondrial genes from 13 transcriptomes, corresponding to five families not represented in GenBank, for a final dataset of 113 taxa. Because mitogenomic data are prone to reconstruction artefacts, eight different evolutionary models were applied to reconstruct phylogenetic trees with IQTREE, RAxML and MrBayes. If the over‐parametrization of some models produced trees with aberrant internal long branches, the global topology of the trees remained stable over models and softwares, and several relationships were revealed or found supported here for the first time. However, even if our dataset encompasses 60% of the valid families of neogastropods, some key taxa are missing and should be added in the future before proposing a revision of the classification of the neogastropods. Our study also demonstrates that even complex models struggle to satisfactorily handle the evolutionary history of mitogenomes, still leading to long‐branch attractions in phylogenetic trees. Other approaches, such as reduced‐genome strategies, must be envisaged to fully resolve the neogastropod phylogeny.

The only species of Mohnia Friele, 1879 (Caenogastropoda, Buccinoidea, Buccinidae) in the North Pacific represents an unrecognized new genus of Newtoniellidae (Triphoroidea)

Mohniakurilana Dall, 1913 was described more than 100 years ago from deep waters off the Kuril Islands and remains exceedingly rare in museum collections. Originally placed in the carnivorous neogastropod family Buccinidae, fragmentary soft parts from the type lot and from several specimens belonging to allied species collected in the Aleutian Islands in the 1990s have allowed anatomical investigations for the first time. These have revealed the presence of a paucispiral operculum with an eccentric nucleus, foot with a deep propodial pedal gland and metapodial pedal gland, taenioglossate radula, short acrembolic proboscis, well-developed mid-esophageal gland, glandular prostate, and the absence of a penis; the nervous system is epiathroid with a long supra-esophageal connective and numerous statoconia in the statocysts. Analysis of the gut contents revealed abundant halichondriid sponge spicules. This evidence indicates a placement in the Triphoroidea, a diverse superfamily of specialized spongivores. Mohniakurilana is transferred to the Newtoniellidae and placed in the new genus Pseudomohniagen. nov.Pseudomohniarogerclarkisp. nov. is established for a new species from the Aleutian Islands characterized by its narrowly turreted shell and distinctive multicuspid rachidian. A lectotype is designated for Mohniakurilana.