Does sargassum contribute to meiofauna dispersal? The case of tardigrades and nematodes in the Mexican Caribbean.

The knowledge of the long-distance dispersal mechanisms of meiofauna is still limited. Rafting is considered as the main mechanism of dispersal of the meiofauna. The recent events of the Sargassum spp. arrival in the Caribbean provides the opportunity to explore long distance mechanisms. Four samples of floating Sargassum spp. were collected from the water column in Xcalak, Quintana Roo, which arrived at the Reef lagoon and Mangrove fringe. A total of 425 organisms were present, 388 nematodes, 36 tardigrades, and a single acarus. Tardigrades were represented by three species, whereas nematodes were represented by 16 morphotypes. The population of both tardigrades and nematodes was composed of mature and juvenile specimens. One tardigrade was collected during their ecdysis process. Our results suggest that not only the nematodes, but also tardigrades and acari can reach the floating Sargassum spp., maintaining in the algae, growing, and reproducing, while they are transported in the sea. We can conclude that in the Caribbean Sea, the floating Sargassum spp. floating is a dispersal mechanism of nematodes and tardigrades.

The high biodiversity of benthic organisms in a coastal ecosystem revealed by an integrative approach / A alta biodiversidade de organismos bentônicos em um ecossistema costeiro revelada por uma abordagem integrativa

Abstract Increasing habitat modification and species loss demand consistent efforts to describe and understand biodiversity patterns. The BIOTA/FAPESP Program was created in this context and it has been a successful initiative to promote studies on biodiversity and conservation in Brazil. The BIOTA/Araçá is an interdisciplinary project that provided a detailed evaluation of the biodiversity of Araçá Bay, a coastal seascape located on the North coast of the state of São Paulo, Southeast Brazil. The bay encompasses multiple habitats, such as beaches, mangroves, rocky shores, and a tidal flat, and provides important ecosystem services. Unfortunately, the bay is the subject of complex social-environmental conflicts that oppose economic, social, and environmental demands (i.e., the expansion of neighboring harbor activities vs. small-scale artisanal fisheries and protection of biodiversity). The present study presents a survey of the benthic species occurring in the different habitats of Araçá Bay, including data obtained during the BIOTA/Araçá project and previous assessments of the area. The benthic species play an important role in marine environments and studying the diversity of these organisms that live associated with the bottom is indispensable for comprehending the environment's functioning. The macrofauna, meiofauna, and microorganisms associated with soft and hard bottom were listed, and additional information, such as the habitat and geographical distribution, were provided for each species. The checklist includes 826 species, almost 70% recorded during the BIOTA/Araçá project. The most speciose taxa were the annelids (225 spp.), mollusks (194 spp.), and crustaceans (177 spp.). Seven benthic species are endemic to Araçá Bay, 14 are considered threatened, and seven are economically exploited. Furthermore, the bay is the type locality of many taxa, and 11 new benthic species were described based on specimens sampled during the project. This project shows the importance of Araçá Bay as a unique biologically rich environment and highlights the need for conservation efforts in light of the current threats.

Resumo O aumento da modificação dos habitats e da perda de espécies demanda esforços consistentes para descrever e compreender os padrões de biodiversidade. O programa BIOTA/FAPESP foi criado nesse contexto e é uma iniciativa de sucesso para promover estudos em biodiversidade e conservação no Brasil. O BIOTA/Araçá é um projeto interdisciplinar que promoveu uma avaliação detalhada da biodiversidade da Baía do Araçá, um ecossistema costeiro localizado ao Norte do estado de São Paulo, Sudeste do Brasil. A baía engloba múltiplos habitats, tais como praias, manguezais, costões rochosos, e uma planície de maré, e também fornece importantes serviços ecossistêmicos. Infelizmente, a baía está sujeita à conflitos sócio-ambientais complexos que contrastam demandas econômicas, sociais e ambientais (i.e. a expansão das atividades do porto vizinho vs. a pesca artesanal de pequena escala e a proteção da biodiversidade). O presente estudo apresenta um levantamento das espécies bentônicas que ocorrem nos diferentes habitats da Baía do Araçá, incluindo dados obtidos durante o projeto BIOTA/Araçá e de investigações realizadas anteriormente na área. As espécies bentônicas desempenham um papel importante no ambiente marinho, e estudar a diversidade desses organismos que vivem associados ao fundo é indispensável para compreender o funcionamento do meio ambiente. A macrofauna, meiofauna, e microorganismos associados aos fundos consolidado e inconsolidado foram listados, e informações adicionais foram fornecidas para cada espécie, tais como a distribuição geográfica e nos habitats. O checklist inclui 826 espécies, quase 70% registradas durante o projeto BIOTA/Araçá. Os taxa mais especiosos foram os anelídeos (225 spp.), moluscos (194 spp.), e crustáceos (177 spp.). Entre as espécies bentônicas listadas, sete são endêmicas da Baía do Araçá, 14 são consideradas ameaçadas de extinção, e sete são exploradas economicamente. A baía é a localidade tipo de vários taxa, e 11 novas espécies bentônicas foram descritas com base em espécimes amostrados durante o projeto. Este projeto mostra a importância da Baía do Araçá como um ambiente de riqueza biológica única e demonstra a necessidade de esforços para a sua conservação considerando as atuais ameaças.

Effects of microplastics pollution on the abundance and composition of interstitial meiofauna

Introduction: Pollution by microplastics is a global problem in marine environments, which impacts microorganisms and ecosystems at several spatial levels. Sandy beaches are depositional environments where microplastics tend to accumulate in large quantities. The co-occurrence of interstitial meiofauna and microplastics in sand grains raises the question on whether the accumulation of microplastics in the sediments affects the abundance and composition of the meiofaunal communities. Objective: To test the hypothesis that microplastics affect the meiofauna of urban sandy beaches. Methods: We studied the three main urban sandy beaches of Santa Marta, Colombia: El Rodadero, Santa Marta Bay, and Taganga. All are similar in morphology and external pressures, and differ from other beaches in the region. In April 2019 we collected 81 sand samples, equally distributed in the intertidal zone (upper, mid, and lower intertidal levels). We applied generalized linear models to abundance, and multivariate permutational tests to community composition. Results: We identified 17 taxonomic groups of meiofauna, and microplastic particles (mainly 45-500 micron fibres) evenly distributed across beaches and intertidal levels. There was more meiofauna at the mid intertidal level, and in fine and medium grain sediment. At the lower intertidal level, sites with more microplastics had less meiofauna. Abundance of microplastics explained 39 % of the variation in meiofaunal community composition at lower intertidal levels. Conclusions: The accumulation of microplastics might have a negative impact on these meiofaunal interstitial communities. This is not surprising: if microplastics occupy the same physical space as these animals, they might presumably modify the structure of sediments and the composition of interstitial water.

Introducción: La contaminación por microplásticos es un problema global en los ecosistemas marinos, con impacto sobre microorganismos y ecosistemas en varios niveles espaciales. Las playas arenosas son ambientes de deposición donde se tiende a acumular gran cantidad de microplásticos. La co-ocurrencia de meiofauna intersticial y microplásticos en granos de arena plantea la pregunta de que si la acumulación de microplásticos en sedimentos afecta la abundancia y composición de comunidades de meiofauna. Objetivo: Probar la hipótesis de que microplásticos afectan la meiofauna de playas arenosas urbanas. Métodos: Estudiamos las tres principales playas arenosas urbanas de Santa Marta, Colombia: El Rodadero, Bahía Santa Marta y Taganga. Estas son similares en morfología y presiones externas, y difieren de las otras playas de la región. En abril 2019 recolectamos 81 muestras de arena, distribuidas de manera equidistante en la zona intermareal (nivel intermareal superior, medio y bajo). Aplicamos modelos lineales generalizados de abundancia, y pruebas permutacionales multivariantes a la composición de comunidades. Resultados: Identificamos 17 grupos taxonómicos de meiofauna, y partículas de microplástico (principalmente fibras de 45-500 micras) distribuidos equitativamente a lo largo de las playas y niveles intermareales. Hubo más meiofauna en el nivel intermareal medio, y en sedimentos de grano mediano y fino. A niveles intermareales más bajos, sitios con más microplásticos tuvieron menos meiofauna. La abundancia de los microplásticos explicó el 39 % de la variación en comunidades de meiofauna a niveles intermareales bajos. Conclusión: La acumulación de microplásticos podría tener un impacto negativo sobre las comunidades de meiofauna intersticial. Esto no es de sorprender: si los microplásticos ocupan el mismo volumen físico que estos animales, estos podrían presuntamente modificar la estructura de sedimentos y la composición del agua intersticial.

Transition of an estuarine benthic meiofauna assemblage 1.7 and 2.8 years after a mining disaster.

Background: Estuaries are transitional coastal ecosystems that are threatened by multiple sources of human pollution. In 2015, mining tailings from an upstream dam failure caused massive metal contamination that impacted benthic assemblages on the Brazilian Rio Doce estuary. Methods: In this study, we investigate and compare meiofaunal assemblages with eDNA metabarcoding 1.7 years (2017) and 2.8 years (2018) after the initial contamination by mine tailings in order to evaluate the continued impact of sediment mine tailing contaminants on the structure of benthic assemblages after the disaster. Results: The community was dominated by Arthropoda and Nematoda 1.7 yr after the impacts (42 and 29% of meiofaunal sequence reads, respectively) but after 2.8 years Arthropoda (64.8% of meiofaunal sequence reads) and Rotifera (11.8%) were the most common taxa. This continued impact on meiofaunal assemblage revealed a lower phylogenetic diversity (7.8-fold) in 2018, despite overall decrease in metal concentration (Al, Ba, Cr, As, Fe, Zn, Mn, Pb, Cd, Co) in sediments. Our data suggests that differences in benthic assemblages and loss of diversity may be influenced by contaminants in sediments of this estuary, and indicate that broad eDNA assessments are greatly useful to understand the full range of biodiversity changes in dynamic estuarine ecosystems.

Two new species of Cyatholaimidae (Nematoda: Chromadorida) from the Southeastern Brazilian coast with emphasis on the pore complex and lateral pore-like structures.

Cyatholaimidae is a common and diverse family of mainly marine nematodes, potentially, with a large number of species to be discovered. The taxonomy of the group is marked by a lack of information about the evolutionary history of the characters and of detailed descriptions of morphological structures that may be taxonomically relevant. Two new species of the family are described from a sublittoral region in Southeastern Brazil, emphasizing the importance of the distribution and morphology of pore complex and pore-like structures present on the cuticle. The taxonomic importance of the cuticle ornamentation and spicule shape for the Biarmifer species, as well as the precloacal supplements structures of Pomponema species, are discussed. Biarmifer nesiotes sp. nov. differs from other species of the genus by the presence of eight longitudinal rows of pore complex on the cuticle and by the shape of the copulatory structure. Pomponema longispiculum sp. nov. differs from the most similar species, P. stomachor Wieser, 1954, by the smaller number of turns of the amphidial fovea, the shorter tail and the beginning of the cuticle lateral differentiation (3/4 of the pharynx length vs. end of the pharynx, respectively). We also obtained the SSU rDNA sequence from Pomponema longispiculum sp. nov., which is closely related to Pomponema sp. (MN250093) by about 91%. Updated tabular keys to species identification of each genus (Biarmifer and Pomponema) are included, containing morphometric data, characters related to cuticle ornamentation, and copulatory structures.

A functional perspective of nematode assemblages as proxy of quality in tropical estuarine tidal flats.

Functional aspects of biological communities influence ecosystem processes and it is urgent to understand how human disturbances affect functional diversity and ecosystem functions and services. Our purpose was to address the use of different functional metrics of nematode assemblages to evaluate the ecological status of tropical estuaries subjected to different human activities, aiming to advance and improve the knowledge about the usefulness of functional attributes as indicators of environmental quality. Three approaches were compared: functional diversity indexes, single trait, and multi traits using the Biological Traits Analysis. The RLQ + fourth-corner combined method was used to identify relationships among functional traits, inorganic nutrients, and metals concentrations. Lower values of FDiv, FSpe, and FOri indicate a convergence of functions, characterizing impacted conditions. A dominant set of traits was related to disturbance, mainly inorganic nutrient enrichment. All the approaches allowed for the detection of disturbed conditions, however, multi traits was the most sensitive one.

Georeferenced database and interactive online map of limnoterrestrial and freshwater Tardigrada from Central and South America / Banco de dados georreferenciado e mapa interativo online de Tardigrada terrestres e aquáticos da América Central e América do Sul

Abstract Like other meiofaunal organisms, tardigrades suffer from a significant knowledge gap concerning many aspects of their biodiversity. The lack of an up-to-date digital collection with all species and details of limnoterrestrial and freshwater tardigrades in South and Central America is one of the most critical gaps to be filled. Therefore, the present work aims to develop a database containing all valid species of limnoterrestrial and freshwater tardigrades from South and Central America found until 2023 and provide open access to the results. Data for each species were obtained directly from the literature using Google Scholar and the website tardigrada.net. This compiled data resulted in the creation of a database with the species name, author and year of species description, genus, family, class, type country, type location, coordinates (longitude and latitude), if it is aquatic and/or limnoterrestrial, substrate where it was found, the country and location of collection, and manuscript containing the species identification. Furthermore, the coordinates of each occurrence were plotted on maps with political-administrative boundaries and Neotropical and Andean biogeographic regions. In addition, statistical analysis was performed related to the geographic distribution of the sampling effort. From the literature, 2157 records of valid non-marine Tardigrada species, endemic or not, were computed. From these records, 271 species of tardigrades have been identified in the two regions combined, with 223 species in South America and 129 species in Central America. We were able to show that there are still many biases in the sampling of tardigrades in the Neotropical and Andean regions and that further studies are needed on the biogeography of these meiofaunal organisms in these biogeographic regions. We expect this database to help better understand the richness and distribution patterns of limnoterrestrial and aquatic tardigrade species in Central and South America.

Resumo Tardígrados, assim como outros organismos meiofaunais, possuem uma lacuna de conhecimento significativa acerca de muitos aspectos da sua biodiversidade. A inexistência de um acervo digital, e atualizado, com todas as espécies e detalhes de tardígrados limnoterrestres e aquáticos na América Central e Sul é uma das lacunas mais importantes a serem preenchidas. Dessa maneira, o presente trabalho tem como objetivo elaborar e disponibilizar, de maneira gratuita, um banco de dados contendo todas as espécies válidas de tardígrados limnoterrestres e aquáticos das América do Sul e América Central encontradas até 2023. Os dados de cada espécie foram obtidos diretamente na literatura, utilizando o Google Scholar e o site tardigrada.net. Com todos esses dados compilados, foi elaborado um banco de dados com nome da espécie, autor e ano de descrição da espécie, gênero, família, classe, país tipo, local tipo, coordenadas (longitude e latitude), se é aquático e/ou limnoterrestre, substrato onde foi encontrado, país coletado, local de coleta e manuscrito com a identificação da espécie. Ademais, as coordenadas obtidas de cada ocorrência foram plotadas em mapas das fronteiras político-administrativas e das regiões biogeográficas Neotropical e Andina. Além disso, uma análise estatística quanto à distribuição geográfica do esforço amostral foi feita. Da literatura, foram computados 2157 registros de espécies válidas de tardígrados limnoterrestre, endêmicas ou não. Desses registros, foram descobertas, até hoje, 271 espécies de tardígrados entre as duas regiões, com 223 espécies na América do Sul e 129 espécies na América Central. Foi possível demonstrar que ainda há muito viés na amostragem de tardígrados nas regiões Neotropical e Andina, e mais estudos acerca da biogeografia desses organismos meiofaunais nessas regiões biogeográficas são necessários. A partir desse banco de dados, espera-se contribuir para um maior entendimento da riqueza e dos padrões de distribuição de espécies de tardígrados limnoterrestres e aquáticos nas América Central e Sul.

Three new species of Microlaimus (Nematoda: Microlaimidae) from the South Atlantic.

Three new species of Microlaimus are described from the continental shelf of the Campos Basin, southwest Atlantic, Brazil. Microlaimus campiensis sp. n. differs from all other species in the presence of two anterior testes, slender spicules with enlarged proximal ends, 7-11 pre-cloacal papilliform supplements, and females with a pair of constriction structures, one on each branch of the ovary. Microlaimus alexandri sp. n. shows sexual dimorphism in the size of the amphidial fovea, which occupies 100% of the diameter of the corresponding area in the male; the buccal cavity provided with five teeth and a slightly cuticularized cuticular ring. Microlaimus vitorius sp. n. has four longitudinal-lateral rows of glands associated with small pores, one seta and three pores small pre-cloacal, and the gubernaculum has a triangular base. An amendment to the diagnosis of the genus is proposed, where the number of teeth was modified.

Gastrotrichs and tardigrades in a remnant of Atlantic Forest (Serra do Japi, SP, Brazil) / Gastrótricos e tardígrados em um remanescente de Mata Atlântica (Serra do Japi, SP, Brasil)

Abstract: Serra do Japi, located in the southeast of São Paulo State, is considered a priority area for conservation, as it houses original Atlantic Forest cover remains. Despite the significant number of studies about vertebrates and invertebrates that were carried out in this region, the meiofauna biodiversity is completely unknown. Thus, the present study aimed to investigate for the first time freshwater Gastrotricha and limnoterrestrial Tardigrada in Serra do Japi Biological Reserve. Samples of sediments, periphyton and floating vegetation in reservoirs and natural lagoons, and mosses growing on native and non-native tree trunks were collected in May 2019. At least five gastrotrichs morphotypes were identified and three of them were formally described: Chaetonotus acanthocephalus, C. dadayi (first record in Brazil), and Heterolepidoderma mariae (first record outside the type locality). In regards to tardigrades, twelve morphotypes were identified and four of them were formally described: Pseudechiniscus juanitae, Minibiotus cf. acontistus, Echiniscus dreyfusi and Itaquascon umbellinae (last two species reported for the first time outside the type locality). This study reinforces that meiofaunal diversity and distribution have been underestimated, even in one of the five largest hotspots in the world.

Resumo: A Serra do Japi, localizada no sudeste do Estado de São Paulo, é considerada uma área prioritária para conservação, por abrigar vestígios de cobertura original de Mata Atlântica. Apesar do número significativo de estudos sobre vertebrados e invertebrados realizados nesta região, a biodiversidade de grupos meiofaunais é completamente desconhecida. Assim, o presente estudo teve como objetivo investigar pela primeira vez Gastrotricha de água doce e Tardigrada limnoterrestre na Reserva Biológica da Serra do Japi. As amostras de sedimentos, perifíton e vegetação flutuante em reservatórios e lagoas naturais, e musgos presentes em troncos de árvores nativas e não nativas foram coletadas em maio de 2019. Foram encontrados cinco morfotipos de gastrótricos, sendo que apenas três deles já foram formalmente descritos: Chaetonotus acanthocephalus, C. dadayi (primeiro registro no Brasil) e Heterolepidoderma mariae (primeiro registro fora da localidade-tipo). Em relação aos tardígrados, foram identificados doze morfotipos, sendo que quatro deles já formalmente descritos: Pseudechiniscus juanitae, Minibiotus cf. acontistus, Echiniscus dreyfusi e Itaquascon umbellinae (as duas últimas espécies relatadas pela primeira vez fora da localidade-tipo). Este trabalho reforça que a diversidade e distribuição da meiofauna têm sido subestimadas, mesmo em um dos cinco maiores hotspots do mundo.

New species of Duplominona Karling, 1966 (Platyhelminthes, Proseriata) from the Pacific coast of Panama.

Eight new species of Duplominona (Platyhelminthes, Proseriata, Monocelididae) are described from the Pacific coast of Panama. They differ from their congeners in the detailed morphology of hard structures associated with the copulatory organ. Duplominona basidilatata n. sp. has a cirrus provided with 5-6 rows of triangular spines, 3-8 µm long, with a large, flat, poorly sclerotized basis. D. hystricina n. sp. has 10-12 rows of needle-shaped spines, 3.5-15 µm long, with a swollen basis. The cirrus of D. hyperhystricina n. sp. is provided with 20-25 rows of slender spines 1.5-9 µm long, with a recurved distal tip. In D. veracruzensis n. sp., cirrus spines increase abruptly in size, from 1.5-2 µm to 6-7 µm. D. uniserta n. sp. has a very long seminal vesicle and a small cirrus, provided with one girdle of hook-shaped spines, 3-5 µm long. D. macrodon n. sp. has one girdle of large, triangular spines, 8-18 µm long. Both D. trimera n. sp. and D. pseudotrimera n. sp. have a tripartite tail, and their cirrus is provided with a stylet. In D. trimera n. sp., the stylet is surrounded by 15-20 rows of spines, 6.5-10 µm long, while D. pseudotrimera n. sp. has 6-8 rows of large spines, 7-22 µm long. D. uniserta n. sp. and D. aduncospina Curini-Galletti, 2019 from the Caribbean coast of Panama have few rows of morphologically nearly identical spines, and are possible candidates as trans-isthmian geminate species. The presence of species with a tripartite tail on both sides of the Isthmus of Panama suggests the possibility of further geminate species pairs; however, no support could be obtained on the basis of the morphology of their hard structures. Five of the eight new species of Duplominona have been found in a single locality, and the diversity of genus along the Pacific coast of Panama may be far higher than present contribution suggests.

Assessing biodiversity shortfalls of freshwater meiofauna from the Atlantic Forest: New species, distribution patterns and the first total-evidence phylogeny of semiplanktonic Gastrotricha.

The Brazilian Atlantic forest is a tropical rainforest recognized as a hotspot of biodiversity, with high species richness and endemicity. This forest extends over a wide latitudinal range, bordering the entire Brazilian coastline, from sea level to high mountains over 2000 m.a.s.L., and presents a variety of environmental conditions and forest physiognomy. Despite many years of intense studies on animal biodiversity in the biome, there is a lack of information on meiofauna taxa causing several shortfalls in biodiversity knowledge of these tiny organisms. In this study, we address some of these shortfalls by describing a new species of Neogossea (Gastrotricha: Chaetonotida) from a lentic ecosystem in southeastern Brazil, surrounded by fragments of Atlantic Forest by using an integrative approach combining different morphological techniques and molecular data. We also point out new hypotheses of homologous structures due to scanning electron microscope observations of the new species. Additionally, we used two numerical methods to assess distribution patterns and historical regionalization of four freshwater meiofaunal taxa (Gastrotricha, Rotifera, Copepoda and Cladocera). For the first time, we accessed the areas of endemism in this biological hotspot based on aquatic fauna with a very peculiar life history. Due to sampling issues and meiofauna species being widespread, our results raise incongruences with previous endemism analyses on vertebrates and arthropods. Finally, we performed the first total-evidence phylogenetic analyses of benthic and semiplanktonic gastrotrichs based on 59 morphological characters and three molecular markers, employing a parsimony approach. The phylogenetic reconstruction supports the hypothesis of a single origin of semiplanktonic gastrotrichs, and both Dasydytidae and Neogosseidae families are monophyletic taxa as well as four non-monotypic genera.

Marine Tardigrada from the Mexican Caribbean with the description of Styraconyx robertoi sp. nov. (Arthrotardigrada: Styraconyxidae).

Marine tardigrades were sampled at three sites on Mexico's Caribbean coast. Eleven taxa were collected, one of which is described as a new species. Styraconyx robertoi sp. nov. is characterized by: asymmetric primary clavae; dorsal cuticle with a grid-like sculpture; claws with reduced accessory hooks; females with peduncles on only two digits (the external) of legs I-IV; males with peduncles only on the external digits of legs I-III and peduncles on all four digits of leg IV. Styraconyx robertoi sp. nov. is most similar to S. craticuliformis Chang Rho, 1998 and S. kristenseni Renaud-Mornant, 1981 by having asymmetric primary clavae but differs from S. craticuliformis mainly by the number of peduncles and from S. kristenseni mainly by the presence of a grid-like dorsal sculpture. Additionally, a comparison of material collected from the same region, but reported previously only as genus level records, was carried out in order to produce a refined list of the known Mexican marine tardigrade species.

Diversity patterns of free-living nematode assemblages in seagrass beds from the Cuban archipelago (Caribbean Sea).

Diversity patterns of free-living marine nematodes in tropical seagrass beds are understudied. Here, we describe the species richness and assemblage composition of nematodes in 13 seagrass sites covering the whole Cuban archipelago. Nematodes were collected from Thalassia testudinum seagrass beds and identified to species level. We provide a checklist of nematode species from seagrass beds. The species richness of nematode assemblages is high, with 215 species, 138 genus, 35 families, seven orders and two classes. That γ-diversity is higher than other studies and points to seagrass beds as diversity hotspots of free-living marine nematodes. Local species richness in seagrass bed sites is about 57 ± 17 species and broadly similar across the sites, despite the environmental heterogeneity. The geographical distance plays a weak, but significant, role on the decay of similarity likely affected by limited dispersal of nematodes. The pairwise similarity values, related to poor-coloniser nematodes, were twice more affected by the distance than those related to good-colonisers, possibly due to differential success of transport and settlement.

Chronic trace metals effects of mine tailings on estuarine assemblages revealed by environmental DNA.

Mine tailing disasters have occurred worldwide and contemporary release of tailings of large proportions raise concerns of the chronic impacts that trace metals may have on the aquatic biodiversity. Environmental metabarcoding (eDNA) offers an as yet poorly explored opportunity for biological monitoring of impacted aquatic ecosystems from mine tailings and contaminated sediments. eDNA has been increasingly recognized to be an effective method to detect previously unrecognized small-sized Metazoan taxa, but their ecological responses to environmental pollution has not been assessed by metabarcoding. Here, we evaluated chronic effects of trace metal contamination from sediment eDNA of the Rio Doce estuary, 1.7 years after the Samarco mine tailing disaster, which released over 40 million m3 of iron tailings in the Rio Doce river basin. We identified 123 new sequence variants environmental taxonomic units (eOTUs) of benthic taxa and an assemblage composition dominated by Nematoda, Crustacea and Platyhelminthes; typical of other estuarine ecosystems. We detected environmental filtering on the meiofaunal assemblages and multivariate analysis revealed strong influence of Fe contamination, supporting chronic impacts from mine tailing deposition in the estuary. This was in contrast to environmental filtering of meiofaunal assemblages of non-polluted estuaries. Here, we suggest that the eDNA metabarcoding technique provides an opportunity to fill up biodiversity gaps in coastal marine ecology and may become a valid method for long term monitoring studies in mine tailing disasters and estuarine ecosystems with high trace metals content.

A new genus with three new species of free-living marine nematodes of the subfamily Desmodorinae (Nematoda: Desmodoridae), from the continental shelf off northeastern Brazil.

Three new species representing a new genus of marine nematodes were collected on the continental shelf of the Potiguar Basin, northeastern Brazil. Spinonema gen. n. has a coarsely annulated cuticle with the inner layer ornamented with vacuoles, and lateral alae. The lateral alae are formed by raised and bent lateral sections of annules, resembling the letter C. C-shaped refers to each individual segment of ala. Some species have a dorsal spine, arched spicules and a well-developed head capsule, with a thick cuticle without annulations. Spinonema gen. n. has some features in common with certain genera of the family Desmodoridae but can be distinguished by the coarse body annuli, cuticular ornamentation (lateral alae, and in some species a dorsal spine) and the absence of subcephalic setae. The type species of the new genus, Spinonema cuticulatum gen. et sp. n., is characterized by the presence of a spiral fovea amphidialis, hook-shaped spicules in the capitulum, a velum and three ejaculatory glands. Spinonema spirale gen. et sp. n. has body annuli with the inner cuticle ornamented with vacuoles along the entire body, a multispiral fovea amphidialis with 3.15 turns and a gubernaculum intricate, with lateral crurae. Dorsal apophysis of gubernaculum wing-shaped. Spinonema absente gen. et sp. n. has a cryptospiral fovea amphidialis, short spicules, a simple gubernaculum and three precloacal setae.

New species of Duplominona Karling, 1966 and Pseudominona Karling, 1978 (Platyhelminthes: Proseriata) from the Caribbean.

Nine new species of Duplominona and one new Pseudominona (Platyhelminthes, Proseriata, Monocelididae) are described from the Caribbean coast of Panama and from Puerto Rico.                Duplominona aduncospina n. sp.; D. terdigitata n. sp.; D. pusilla n. sp.; D. bocasana n. sp. (from Panama) and D. dissimilispina n. sp.; D. chicomendesi n. sp.; D. macrocirrus n. sp.; D. diademata n. sp.; D. puertoricana n. sp. (from Puerto Rico) can be distinguished from the numerous congeneric species based on fine details of the sclerotized structures of the copulatory organ. Duplominona aduncospina n. sp. is characterised by a cirrus provided with 3-4 rows of recurve spines, 2-3 µm long. D. terdigitata n. sp. shows a tripartite tail, and needle-shaped cirrus spines, 1.5-9 µm long. Cirrus spines of D. pusilla n. sp. are scale-like, 1.5-3 µm long. D. bocasana n. sp. has triangular spines, 1.5-6 µm long. D. dissimilispina n. sp. has needle-shaped spines, 3.5-15 µm long. D. chicomendesi n. sp. has a small cirrus, with few, strongly curved spines, 2-7.5 µm long. D. macrocirrus n. sp. has a large cirrus, provided with spines 3-9 µm long, with the longest spines placed medially. D. diademata n. sp. has a cirrus with two separate spiny areas, with spines 7-13 µm long. D. puertoricana n. sp. has a very long cirrus, with poorly sclerotised proximal spines, and distal spines to 6 µm long. A taxonomic key of the genus Duplominona is provided. Pseudominona cancan n. sp. from Panama differs from P. dactylifera from Bermuda, the only species known in the genus so far, for its shorter cirrus and fewer, triangular spines 3-5 µm long, and for the position of the vagina, close to mouth. A specimen attributed to P. dactylifera collected in Puerto Rico is described. Distribution of the new species suggests a complete separation of Panamanian and Puerto Rican proseriate fauna, confirming previous reports of restricted ranges and high endemicity of mesopsammic Platyhelminthes.

Schizorhynchia (Platyhelminthes, Rhabdocoela) from eastern Cuba, with the description of fifteen new species.

We report on the schizorhynch species collected in a survey in the eastern region of Cuba. Eighteen species were identified, of which only three are known to science: Cheliplana asica, C. terminalis, and Carcharodorhynchus flavidus. The 15 new species belong to three different genera: Cheliplana (five species), Carcharodorhynchus (four species), and Schizochilus (six species). The five new species of Cheliplana (C. gibarenha sp. n., C. santiaguera sp. n., C. spuriaseminalis sp. n., C. subproximalis sp. n. and C. verrucosa sp. n.) differ from their congeners in the detailed morphology of the proboscis hooks and the atrial organs. The proboscis hooks bear a distal small hook in C. verrucosa sp. n., a feature only shared with C. paradoxa. Two of the four new species of Carcharodorhynchus (C. smilodon sp. n. and C. papillaris sp. n. ) are very similar to C. flavidus in that the toothed belts of the proboscis are not continuous. However, they clearly differ from that species and from each other in the detailed construction of the teeth and copulatory organ. Carcharodorhynchus spiniformis sp. n. and C. nativus sp. n. can also be distinguished from the other species of Carcharodorhynchus by the detailed construction of the proboscis teeth and copulatory organ. The six new species of Schizochilus here described show a spiny cirrus around a central stylet. Two species lack the distal sclerotized cap of the copulatory bulb: S. favus sp. n. and S. bueycabonensis sp. n.. All new species of Schizochilus can be distinguished from each other and their congeners by the detailed construction of the hard parts (cirrus and stylet) of the copulatory organ.

The genus Bolbonema Cobb, 1920 (Nematoda: Desmodoridae): emended diagnosis, key to males, and description of three new species from the continental shelf off northeastern Brazil.

The marine nematode genus Bolbonema has three valid species, the most recent one described eight years ago. Characteristics of the genus include the well-defined globular cephalic capsule and the long and short somatic setae along the body. Three previously undescribed species of this genus were collected on the continental shelf of the Potiguar Basin in northeastern Brazil. Bolbonema braziliensis sp. n. has a relatively large cryptospiral fovea amphidialis, gubernaculum a bent rod dorsally oriented and two subventral precloacal setae inserted on two small papillae above the cloaca. Bolbonema papillae sp. n. has a large multispiral fovea amphidialis with three turns, arched spicules with the proximal region rounded, a laminar and well-developed gubernaculum enfolding the distal portion of the spicules, and two subventral precloacal papillae just above the cloaca. Bolbonema zildae sp. n. has a spiral fovea amphidialis, no supplements, arched spicules with a velum, and the gubernaculum with a dorsal apophysis. These three new species increase to six the number of taxa known in the genus. A dichotomous key based on males, an emended diagnosis of the genus, and the first record of Bolbonema brevicolle Cobb, 1920 from Brazil are provided.

Marine tardigrades of the Bahamas with the description of two new species and updated keys to the species of Anisonyches and Archechiniscus.

This is the first survey of subtidal marine tardigrades from the Bahamas, and we compare our results with earlier studies of Bahamian intertidal habitats. In 2011 and 2014 we collected 60 subtidal sand samples from Bimini, the Berry Islands, New Providence, Eleuthera, and the Exumas. We found 11 species only one of which, Dipodarctus subterraneus (Renaud-Debyser, 1959), had been found in the previous intertidal Bahamian collections. Thus, 10 species are new records for the Bahamas, and four of these are new to science. We describe two of the new species (Archechiniscus bahamensis sp. nov. and Anisonyches eleutherensis sp. nov.). Additional material is needed for a conclusive identification of the undescribed species of Batillipes and Florarctus. Based on examination of the holotype of Anisonyches diakidius Pollock, 1975, we redescribe this species and give an emended diagnosis of the genus and the species. We also provide new keys to the species in the genera Archechiniscus and Anisonyches. A Chao2 species richness estimate indicated that our sampling effort was extensive and probably recovered most common species. Correlations of abundance and diversity indices with regard to depth, distance to nearest shore, and sediment grain size were not significant.

Traditional and confocal descriptions of a new genus and two new species of deep water Cerviniinae Sars, 1903 from the Southern Atlantic and the Norwegian Sea: with a discussion on the use of digital media in taxonomy (Copepoda, Harpacticoida, Aegisthidae).

Aegisthidae is one of the most abundant and diverse families of harpacticoid copepods living in deep-sea benthos, and the phylogenetic relationships within the family are in state of flux. Females of two new deep-water species of harpacticoid copepods belonging to the Hasegen. n. (Aegisthidae: Cerviniinae) are described. The first taxonomic description of marine copepod species based on the combined use of interference and confocal microscopy for the study of the habitus and dissected appendages is presented here. CLSM (Confocal Laser Scanning Microscopy) is a non-destructive method, comparable in quality to SEM (scanning electron microscopy) at the same magnifications. To observe and reconstruct in detail the habitus and dissected appendages, whole specimens and dissected parts were stained with Congo Red, mounted on slides with glycerine for CLSM and scanned under three visible-light lasers. Hase lagomorphicusgen. et sp. n. and Hase talpamorphicusgen. et sp. n. were collected from the sediments of the Southern Atlantic and the Norwegian Sea, from 2270 m and 5468 m depths, respectively. Hasegen. n. is included within Cerviniinae based on the caudal rami which are relatively divergent. Hasegen. n. is the sister taxon of Cerviniella based on the following synapomorphies: sturdy body, exopodites 1-3 of pereopods 1-3 heavily built, transformed into digging limbs, with strong outer and distal spines/setae, two-segmented endopod on the pereopods 2 and 3, and a reduced pereopod 5. Compared to Cerviniella, Hasegen. n. exhibits a more developed armature on the pereopod 1, which has outer and distal elements transformed into strong and long spines vs. stiff setae on Cerviniella.Hasegen. n. has one or two strong and long spines on the inner margin of the exopodite 3 of pereopod 4 and pereopod 5 is fused to the somite, ornamented with three distal setae. The telson of Hasegen. n. is subquadratic, and the furca is among the shortest yet described for Aegisthidae. The new species differ in a number of diagnostic characters, three of which are: a) the somite bearing pereopods 3 and 4 with latero-distal spiniform processes in H. talpamorphicusgen. et sp. n. but smooth in H. lagomorphicusgen. et sp. n., b) antenna is armed with three stout spines on the lateral inner margin of the exopod in H. talpamorphicusgen. et sp. n. and two proximal setae in H. lagomorphicusgen. et sp. n., and c) pereopod 4 exopodite 3 has two long and strong spines on the inner margin in H. lagomorphicusgen. et sp. n. and one spine in H. talpamorphicusgen. et sp. n. The high quality of CLSM images should foster discussion about the use of high quality digital images as type or as part of the type series in zoological studies, especially when studying rare and small macrofaunal and meiofaunal taxa.