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Mollusk death assemblages are formed by shell remnants deposited in the surficial mixed layer of the seabed. Diversity patterns in tropical marine habitats still are understudied; therefore, we aimed to investigate the taxonomic, phylogenetic, and functional diversity of mollusk death assemblages at regional and local scales in coral reef sands and seagrass meadows. We collected sediment samples at 11 sites within two shallow gulfs in the Northwestern Caribbean Sea and Southeastern Gulf of Mexico. All the shells were counted and identified to species level and classified into biological traits. We identified 7113 individuals belonging to 393 species (290 gastropods, 94 bivalves, and nine scaphopods). Diversity and assemblage structure showed many similarities between gulfs given their geological and biogeographical commonalities. Reef sands had higher richness than seagrasses likely because of a more favorable balance productivity-disturbance. Reef sands were dominated by epifaunal herbivores likely feeding on microphytobenthos and bysally attached bivalves adapted to intense hydrodynamic regime. In seagrass meadows, suspension feeders dominated in exposed sites and chemosynthetic infaunal bivalves dominated where oxygen replenishment was limited. Time averaging of death assemblages was likely in the order of 100 years, with stronger effects in reef sands compared to seagrass meadows. Our research provides evidence of the high taxonomic, phylogenetic, and functional diversity of mollusk death assemblages in tropical coastal sediments as result of the influence of scale-related processes and habitat type. Our study highlights the convenience of including phylogenetic and functional traits, as well as dead shells, for a more complete assessment of mollusk biodiversity.

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Warmer temperatures and higher sea level than today characterized the Last Interglacial interval [Pleistocene, 128 to 116 thousand years ago (ka)]. This period is a remarkable deep-time analog for temperature and sea-level conditions as projected for 2100 AD, yet there has been no evidence of fossil assemblages in the equatorial Atlantic. Here, we report foraminifer, metazoan (mollusks, bony fish, bryozoans, decapods, and sharks among others), and plant communities of coastal tropical marine and mangrove affinities, dating precisely from a ca. 130 to 115 ka time interval near the Equator, at Kourou, in French Guiana. These communities include ca. 230 recent species, some being endangered today and/or first recorded as fossils. The hyperdiverse Kourou mollusk assemblage suggests stronger affinities between Guianese and Caribbean coastal waters by the Last Interglacial than today, questioning the structuring role of the Amazon Plume on tropical Western Atlantic communities at the time. Grassland-dominated pollen, phytoliths, and charcoals from younger deposits in the same sections attest to a marine retreat and dryer conditions during the onset of the last glacial (ca. 110 to 50 ka), with a savanna-dominated landscape and episodes of fire. Charcoals from the last millennia suggest human presence in a mosaic of modern-like continental habitats. Our results provide key information about the ecology and biogeography of pristine Pleistocene tropical coastal ecosystems, especially relevant regarding the-widely anthropogenic-ongoing global warming.

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Mollusk hemocyanins, among the largest known proteins, are used as immunostimulants in biomedical and clinical applications. The hemocyanin of the Chilean gastropod Concholepas concholepas (CCH) exhibits unique properties, which makes it safe and effective for human immunotherapy, as observed in animal models of bladder cancer and melanoma, and dendritical cell vaccine trials. Despite its potential, the structure and amino acid sequence of CCH remain unknown. This study reports two sequence fragments of CCH, representing three complete functional units (FUs). We also determined the high-resolution (1.5 Å) X-ray crystal structure of an "FU-g type" from the CCHB subunit. This structure enables in-depth analysis of chemical interactions at the copper-binding center and unveils an unusual, truncated N-glycosylation pattern. These features are linked to eliciting more robust immunological responses in animals, offering insights into CCH's enhanced immunostimulatory properties and opening new avenues for its potential applications in biomedical research and therapies.

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Semperula wallacei (Issel, 1874) is a species of terrestrial slug that occurs in southeast China and the Pacific Basin and is the only species of its genus that occurs beyond the Oriental region and to the east of Wallace's line in the Australian region, where it has probably been introduced. In this study, we report for the first time S. wallacei as an intermediate host for Angiostrongylus cantonensis (Chen, 1935) based on histological and molecular analyses of slugs from Tuamasaga, Samoa, deposited at the Medical Malacological Collection (Fiocruz-CMM). DNA was obtained from the deparafinized tissues scraped from specimen slides. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) targeted to the internal transcribed spacer 2 (ITS2) region were carried out using the restriction enzyme Cla I. The RFLP profile observed for our larval specimen of S. wallacei was identical to the profile previously established for A. cantonensis, demonstrating that S. wallacei can be naturally infected with A. cantonensis and is likely to be an intermediate host for this parasitic nematode species in the field. The potential for geographical range expansion of S. wallacei in the Pacific Basin, its small size, and the general role of veronicellids as crop pests and hosts of nematodes, indicate the significance of S. wallacei as an invasive species in the Pacific Basin. Our work also highlights the importance of biological collections for investigating the environmental impact of invasive species on agriculture, public health, and biodiversity conservation.

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The study was conducted to compare the distribution and composition of the Molluscs community in 4 ecosystems (4 sites) in southern of Iraq, namely: (Site 1)- in Euphrates River at Al-Madinah city, (Site 2)- in Shatt Al-Arab at Al-Sharsh area, (Site 3)- in the Garmat Ali River at Al-Mashib area and Site 4- in the Al-seba area. Samples were collected from study sites during a period of January to August 2019. (11) species from the class Gastropoda and (4) species from the class Bivalves, species were predominated in most of the study months which are species: Melenodies nodosa, Bellamya bengalensis and Melanopsis turbculata from Gastropoda and two of the species are bivalve: Corbicula fluminalis and Limnoperna fortunei (Dunker, 1857), and the last species, L. fortunei, was recorded in the current study for the first time in freshwater of Iraq. The total biodiversity values of Molluscs at the Euphrates River at Al-Madinah area (Site. 1), Al-Sharsh area (Site 2), Al-Mashib area (Site 3) and Al-seba area (Site 4) were 3.1, 2.9, 2.4, 1.8, respectively, and It was noted that the highest seasonal densities of the species in the current study were recorded in the winter season, reaching 1013, 905, 762 and 639 individuals / m2 in four sites, respectively.

O estudo foi realizado para comparar a distribuição e composição da comunidade de moluscos em quatro ecossistemas (quatro locais) no sul do Iraque, a saber: Local 1- no rio Eufrates, na cidade de Al-Madinah, Local 2- em Shatt Al-Arab na área de Al-Sharsh, Local 3- no rio Garmat Ali na área de Al-Mashib, e Local 4- na área de Al-Seba. As amostras foram coletadas nos locais de estudo durante um período de janeiro a agosto de 2019. Onze espécies da classe Gastropoda e quatro espécies da classe Bivalves predominaram espécies na maioria dos meses de estudo, que são as espécies Melenodies nodosa, Bellamya bengalensis e Melanopsis turbculata, de Gastropoda, e duas das espécies, Corbicula fluminalis e Limnoperna fortunei (Dunker, 1857), de Bivalvia, e L. fortunei, foram registradas pela primeira vez em água doce do Iraque. Os valores totais de biodiversidade de moluscos no rio Eufrates na área de Al-Madinah (Local 1), área de Al-Sharsh (Local 2), área de Al-Mashib (Local 3) e área de Al-Seba (Local 4) foram 3,1, 2,9, 2,4, 1,8, respectivamente, e notou-se que as maiores densidades sazonais da espécie no presente estudo foram registradas na estação de inverno, chegando a 1013, 905, 762 e 639 indivíduos/m2 em quatro locais, respectivamente.

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Phyllidiid nudibranchs are brightly colored gastropod molluscs, frequently encountered in coral reefs of the tropical Indo-Pacific. This study aimed to identify the phylogenetic similarities among the Phyllidia spp. The phylogenetic similarities among all the available Phyllidia spp. were studied by comparing the nucleotide sequence of 16s rRNA and cytochrome c genes (cox I). Sequences were retrieved from NCBI databases and aligned by using Geneious software. A phylogenetic tree was constructed for the retrieved sequences of Phyllidia spp. by using the neighbor-joining method on MEGA software and the pairwise distances were also calculated. The similarities among nucleotide sequences of 16s rRNA showed that the P. elegans, and P. haegeli had the highest similarities (99.92%) and the lowest similarities (99.14%) among P. haegeli and P. picta. While nucleotide sequences of cox I showed the highest similarities (99.90%) between P. elegans and P. ocellata, and the P. varicosa had the lowest similarities 99.74% with P. koehleri and P. larryi. The molecular phylogenetic analysis based on mitochondrial marker indicated a close relation between P. elegans and P. alyta in both cox I and 16s rRNA phylogenetic tree. The phylogenetic tree of 16s rRNA gene shows the P. ocellata is closely related to the clade of species P. exquisita. The available phylogenetic analysis could be useful in further studies of Phyllidiidae within Nudibranchia.

Os nudibrânquios Phyllidiid são moluscos gastrópodes de cores vivas, frequentemente encontrados em recifes de corais do Indo-Pacífico tropical. Este estudo teve como objetivo identificar as semelhanças filogenéticas entre Phyllidia spp. As semelhanças filogenéticas entre todos os Phyllidia spp. disponíveis foram estudados comparando à sequência de nucleotídeos dos genes 16s rRNA e citocromo C (cox I). As sequências foram recuperadas dos bancos de dados NCBI e alinhadas usando o software Geneious. Uma árvore filogenética foi construída para as sequências recuperadas de Phyllidia spp. através do método de junção de vizinhos no software MEGA e as distâncias pareadas também foram calculadas. As semelhanças entre as sequências de nucleotídeos do 16s rRNA mostraram que P. elegans e P. haegeli apresentaram as maiores similaridades (99,92%) e as menores similaridades (99,14%) entre P. haegeli e P. picta. Enquanto as sequências de nucleotídeos de cox I apresentaram as maiores similaridades (99,90%) entre P. elegans e P. ocellata, e a de P. varicosa apresentou as menores similaridades 99,74% com P. koehleri e P. larryi. A análise filogenética molecular baseada no marcador mitocondrial indicou uma estreita relação entre P. elegans e P. alyta tanto na árvore filogenética cox I quanto 16s rRNA. A árvore filogenética do gene 16s rRNA demonstrou que P. ocellata está intimamente relacionado ao clado da espécie P. exquisita. A análise filogenética disponível pode ser útil para estudos posteriores de Phyllidiidae dentro de Nudibranchia.

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We describe the first recorded association between fishes and nudibranchs in epipelagic waters. In situ observations and photographs of a juvenile spotted driftfish Ariomma regulus (Stromateiformes; Ariommatidae) swimming alongside the planktonic nudibranch Phylliroe lichtensteinii (Gastropoda; Phylliroidae) were made during blackwater scuba dives off Palm Beach, Florida, United States of America. In this paper, we describe this behavior, highlighting a previously undocumented zooplanktonic host used by fishes. This finding also demonstrates the importance of community science in advancing our understanding of the early life history of marine species.

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Terrestrial molluscs can become agricultural pests and transmit parasites, playing an important role in different biological communities. In the present study, we evaluated the diversity and abundance of this group in two horticultural areas in Rio de Janeiro (Manguinhos and Jacarepaguá neighborhoods), as well the presence of parasitic nematodes associated with these molluscs. We collected specimens in the austral spring and summer, with four sites being sampled within each study area, including malabar spinach, sweet potato, chicory greens, and cassava plantations, and one site in an adjacent, non-cultivated area. We collected a total of 522 live mollusc specimens and identified 16 species from 10 different families. The greatest abundance of molluscs was recorded in summer (363) and at Jacarepaguá (309). Overall, 174 (57%) of the 303 specimens analyzed parasitologically were positive for nematodes. Larvae of superfamily Metastrongyloidea, which includes nematodes that are a concern for public health and veterinary medicine, were found parasitizing the slug Sarasinula linguaeformis, in Manguinhos. Our results contribute to understanding of the diversity of terrestrial molluscs occurring in kitchen gardens in the city of Rio de Janeiro, and provide important insights for generating subsidies for health education actions and control of parasitic diseases transmitted by them.

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The San Matías gulf is a marine biodiversity hotspot located in the Argentinean Patagonia. Although there are several studies on gastropod mollusks from Argentina, nudibranchs remain less studied. In this faunistic assessment 15 species of nudibranchs were found in San Matías gulf, including two new family records for Argentina: Coryphellidae and Dotidae. Although Magellanic nudibranchs are clearly predominant in this area, warm water species such as Doto uva and Coryphella cf. verta are recorded and the known geographic range of five species is extended. In addition, Rostanga pulchra and Diaulula hispida extend their range to the north of the Argentine Patagonia.

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Physids belong to Class Gastropoda; Phylum Mollusca have important position in food web and act as bio indicators, pests and intermediate host. Being resistant these are called cockroaches of malacology. Physid snails were collected from different water bodies of Faisalabad (Punjab) and were identified up to species using morphological markers. The morphometry of the specimens was carried out with the help of a digital Vernier caliper in millimeters (mm) using linear measurement of shell characters. Linear regression analysis of the AL/SW ratio vs AL and SL/SW ratiovs AL indicated that allometric growth exists only in Physa acuta when compared with P.gyrina and P. fontinalis. This study will lead to assess the status of the Physid species in Central Punjab. The Principal component analysis shows that the Component 1 (Shell Length) and component 2 (Shell Width) are the most prolific components and nearly 80 percent of the identification. The distance between P. acuta and P. fontinalis is 5.4699, P. acuta and P. gyrina is 7.6411, P. fontinalis and P. gyrina is 16.6080 showing that P. acuta resembles with P. fontinalis, and both these specimens donot resemble with P. gyrina. P.acuta is an invasive species and shows bioactivity making it a potent candidate for bioactive substances.

Os físidos pertencem à classe Gastropoda; o filo Mollusca possui importante posição na teia alimentar e atua como bioindicador, praga e hospedeiro intermediário. Por serem resistentes, são chamadas baratas de malacologia. Os caramujos físidos foram coletados em diferentes corpos d’água de Faisalabad (Punjab) e identificados até as espécies por meio de marcadores morfológicos. A morfometria dos corpos de prova foi realizada com auxílio de paquímetro digital Vernier em milímetros (mm) por meio de medida linear dos caracteres da casca. A análise de regressão linear da razão AL / SW vs. AL e razão SL / SW vs. AL indicou que o crescimento alométrico existe apenas em Physa acuta quando comparado com P. gyrina e P. fontinalis. Este estudo levará a avaliar a situação das espécies de físido no Punjab Central. A análise do componente principal mostra que o componente 1 (comprimento da casca) e o componente 2 (largura da casca) são os componentes mais prolíficos e quase 80% da identificação. A distância entre P. acuta e P. fontinalis é 5,4699, P. acuta e P. gyrina é 7,6411, P. fontinalis e P. gyrina é 16,6080, mostrando que P. acuta se assemelha a P. fontinalis, e ambos os espécimes não se parecem com P. gyrina. P. acuta é uma espécie invasora e apresenta bioatividade, tornando-se uma candidata potente para substâncias bioativas.

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