One more place to call home: the invasive bivalve Mytilopsis leucophaeata reaches the Maricá-Guarapina lagoon system (Rio de Janeiro, Brazil) / Mais um lugar para chamar de casa: o bivalve invasor Mytilopsis leucophaeata alcança o sistema lagunar Maricá-Guarapina (Rio de Janeiro, Brasil)

Abstract Mytilopsis leucophaeata is an estuarine bivalve native from the Gulf of Mexico and Southeast USA, and it was introduced in Europe, Asia, Caribbean, South America and Northeast USA, showing massive colonization skills. In Brazil, the single invasion records of M. leucophaeata occur in the city of Rio de Janeiro, i.e., in the Rodrigo de Freitas Lagoon and in the Marapendi Lagoon. We conducted a new series of fieldworks in estuaries from the Rio de Janeiro state in order to evaluate the propagation of this invasive bivalve, aiming sites with proper salinities for the establishment of M. leucophaeata. A new record is given for the Maricá-Guarapina lagoon system, where M. leucophaeata mainly colonizes hard substrata (such as piers and rocks), reaching a mean density up to 43,375 specimens/m2; however, aggregates of M. leucophaeata were also observed in the soft substratum. Based on mitochondrial sequences, the taxonomic identification of the invasive bivalve was confirmed. The associated fauna to the agglomerates of M. leucophaeata in the lagoon system comprises amphipods, barnacles, tanaidaceans, isopods, crabs, polychaetes and snails. The expansion of M. leucophaeata requires a continuous investigation due to the great circulation of boats in the littoral of the Rio de Janeiro state and the increased chance of new introductions.

Resumo Mytilopsis leucophaeata é um bivalve estuarino originário do Golfo do México e Sudeste dos EUA, tendo sido introduzido na Europa, Ásia, Caribe, América do Sul e Nordeste dos EUA, e apresentando massiva capacidade de colonização. No Brasil, os únicos registros de invasão de M. leucophaeata ocorrem no município do Rio de Janeiro, i.e., na Lagoa Rodrigo de Freitas e na Lagoa de Marapendi. Este estudo propõe um novo levantamento de campo em estuários fluminenses para avaliar a propagação desse bivalve invasor, visando locais com salinidade propícia para o estabelecimento de M. leucophaeata. Um novo registro é feito para o complexo lagunar Maricá-Guarapina, onde M. leucophaeata coloniza principalmente substratos duros (como píers e rochas), chegando a uma densidade média de 43.375 indíviduos/m2; porém, agregados de M. leucophaeata também foram observados em substrato inconsolidado. Com base em sequências mitocondriais, a identificação taxonômica do bivalve invasor foi confirmada. A fauna associada aos aglomerados de M. leucophaeata no complexo lagunar compreende anfípodes, cracas, tanaidáceos, isópodes, caranguejos, poliquetas e gastrópodes. A expansão de M. leucophaeata demanda uma investigação contínua devido ao alto fluxo de embarcações no litoral fluminense e elevada probabilidade de novas introduções.

Are invasive species always negative to aquatic ecosystem services? The role of dark false mussel for water quality improvement in a multi-impacted urban coastal lagoon.

The dark false mussel Mytilopsis leucophaeata occurs as non-native species in Asia, Europe and South America. Despite the low population density usually found in its native range, M. leucophaeata forms dense clusters in newly invaded areas which lead to impacts on local organisms and environment. Some of the impacts of non-native species on newly colonized areas may be positive. However, despite the empirical evidences of increase in water transparency by freshwater dresseinids, the hypothesis that dark false mussel enhances the quality of brackish water has never been tested so far. Thus, the present study aimed to determine M. leucophaeata impacts on the water quality of a nutrient-enriched coastal lagoon by (1) analyzing a historical water dataset for pre- and post-invasion at Rodrigo de Freitas Lagoon (Brazil) and (2) experimentally testing dark false mussel direct effects on water quality. Historical field data evidenced significant lower phytoplankton abundance and chlorophyll a, and higher water transparency for the post-invasion period. These pattens were also supported by time-series analyses, which detected a decreasing trend for total coliforms density and an increased trend for dissolved oxygen over time. Moreover, time series indicated a gradual increase in lagoon water level with time, but none or minor changes were evidenced for floodgates operation routine, meteorological variables, and the frequency of sewage input. In microcosms, M. leucophaeata was effective to increase water transparency and decrease E. coli densities. The combination of field and laboratory data partially supported the hypothesis that M. leucophaeata invasion promoted an improvement in lagoon water quality, but increased phosphorus availability through excretion in microcosm assays. Management of dark false mussel populations seems to be a potential strategy for water quality improvement within already invaded systems where high sewage-enriched effluents are released. However, as non-native species often unbalance ecological relationships and functioning of the invaded ecosystems, new introductions of M. leucophaeata must be avoided.

Morphology and distribution of the freshwater mussel Diplodon granosus, a rare and poorly understood species

Diplodon granosus was one of the first freshwater mussels to be described for South America. However, the status of the species was confusing for a long time, receiving different taxonomic treatments. In this paper, we redescribe the shell, with new data on the soft parts and information on the distribution and conservation of D. granosus, a rarely recorded species. The shell is thin, not inflated; the macrosculpture is composed only by granules that cover the whole shell, not forming bars; the microsculpture comprises short spikes. In the soft parts we highlight the few, weak and irregularly distributed lamellar connections of the outer demibranch and some features of the stomach, such as the distally enlarged minor typhlosole. There are records of D. granosus over a large area of South America, from Guiana to Argentina. However, most of these records are related to other species and the distribution of D. granosus is restricted to the north of South America in the basins of the Amazonas and Orinoco rivers, and coastal rivers in between. Despite this wide distribution, the species occurs in specific habitats, mainly streams (igarapés), resulting in an extremely fragmented occurrence. Thus, any disturbance to these habitats can threat this freshwater mussel. (AU)

Freshwater mollusks and environmental assessment of Guandu River, Rio de Janeiro, Brazil / Moluscos de água doce e avaliação ambiental do rio Guandu, Rio de Janeiro, Brasil

Abstract The Guandu River Basin is extremely important to state of Rio de Janeiro, as a water supplier of several municipalities. However, the malacological knowledge and environmental status is not well known to this basin. The aim of this paper is to present an inventory of freshwater mollusks, as well as an environmental assessment through a Rapid Assessment Protocol, of ten sampling sites at Guandu River basin in six municipalities (Piraí, Paracambi, Japeri, Seropédica, Queimados and Nova Iguaçu). Thirteen species of molusks were found, eight native (Pomacea maculata, Biomphalaria tenagophila, Gundlachia ticaga, Gundlachia radiata, Omalonyx matheroni, Diplodon ellipticus, Anodontites trapesialis and Eupera bahiensis) and five exotics (Melanoides tuberculata, Ferrissia fragilis, Physa acuta, Corbicula fluminea and Corbicula largillierti). The environmental analysis ranked most sites as "modified". The expansion of exotic species with their associated negative effects, as well the gap in knowledge of native species calls attention to the need of future studies of biology and ecology of the species found.

Resumo A bacia do rio Guandu é de extrema importância para o estado do Rio de Janeiro, pois abastece grande parte da região metropolitana. Contudo, aspectos malacológicos e ambientais desta bacia são pouco conhecidos. O presente trabalho teve por objetivo realizar um inventário das espécies de moluscos de água doce ocorrentes na região, assim como uma avaliação ambiental através de um Protocolo de Avaliação Rápida, de dez estações de coleta na bacia do rio Guandu em seis municípios (Piraí, Paracambi, Japeri, Seropédica, Queimados e Nova Iguaçu). Foram encontradas 13 espécies, sendo oito nativas (Pomacea maculata, Biomphalaria tenagophila, Gundlachia ticaga, Gundlachia radiata, Omalonyx matheroni, Diplodon ellipticus, Anodontites trapesialis e Eupera bahiensis) e cinco exóticas (Melanoides tuberculata, Ferrissia fragilis, Physa acuta, Corbicula fluminea e Corbicula largillierti). A avaliação ambiental caracterizou a maior parte das estações de coleta como "modificado". A dispersão das espécies exóticas e os efeitos negativos a elas associados, além da nossa falta de conhecimento sobre as espécies nativas chama a atenção para a necessidade de futuros estudos biológicos e ecológicos das espécies encontradas.

Freshwater mussels from South America: state of the art of Unionida, specially Rhipidodontini / Bivalves de água doce da América do Sul: estado da arte de Unionida, especialmente Rhipidodontini

Abstract Unionida is the most diverse clade of freshwater bivalves. Among the groups occurring in South America, one with the highest number of species is Rhipidodontini (Hyriidae, Unionida, Paleoheterodonta, Bivalvia). However several issues remains on taxonomy and systematic of this group, leading to problems on species identification, description, as also as a limiting factor to other type of studies (e.g., ecology, conservation,…). In this paper is presented a synthesis of available knowledge about Diplodon Spix in Wagner, 1827 and Rhipidodonta Mörch, 1853 in South America, as a first step in order to a better understating of Rhipidodontini. The evaluation of different authors exposes the little agreement between them that resulted in a sort of divergent taxonomical opinions. Some comments on ecology, conservation and habitat preferences were made. This work can also encourage future research on taxonomy, systematic, ecology and conservation of freshwater mussels in South America.

Resumo Unionida é o clado mais diverso de bivalves de água doce. Entre os grupos que ocorrem na América do Sul, um dos com maior número de espécies é Rhipidodontini (Hyriidae, Unionida, Paleoheterodonta, Bivalvia). Porém, diversas questões taxonômicas e sistemáticas ainda incidem sob este grupo, levando a problemas de identificação de espécies, descrição, entre outros, como também tem atuado como limitador de outros tipos de estudos (e.g., ecologia, conservação,..). Neste trabalho é apresentada uma revisão do conhecimento acerca dos gêneros Diplodon Spix in Wagner, 1827 e Rhipidodonta Mörch, 1853 na América do Sul como um primeiro passo para a melhor compreensão de Rhipidodontini. Avaliando-se diferentes autores, se torna claro a pouca concordância entre eles, resultando em opiniões taxonômicas divergentes. São feitos também alguns comentários sobre ecologia, conservação e preferências ambientais. Este trabalho também deve encorajar futuros trabalhos sobre a taxonomia, sistemática, ecologia e conservação de bivalves de água na América do Sul.

First record of Melanoides tuberculatus (Müller, 1774) and Biomphalaria tenagophila (dïOrbigny, 1835) on Ilha Grande, Rio de Janeiro, Brazil / Primeiro registro de Melanoides tuberculatus (Müller, 1774) e Biomphalaria tenagophila (d´Orbigny, 1835) para a Ilha Grande, Rio de Janeiro, Brasil

Small populations of Melanoides tuberculatus (Müller, 1774) and Biomphalaria tenagophila (dïOrbigny, 1835), were found at Vila do Abraão, being the first record of these species to Ilha Grande, Angra dos Reis, Rio de Janeiro. They were probably introduced after 2004, perhaps following release from aquaria. The possible spread of these species to other freshwater habitats in the island, their effects on native snails and links with public health are discussed. The record of M. tuberculatus appears to be the first for a Brazilian insular area. The recent introduction of these species offers a remarkable opportunity to monitor introduced species and to understand the invasion process in an insular stream in southeastern Brazil.

Pequenas populações de Melanoides tuberculatus (Müller, 1774) e de Biomphalaria tenagophila (dïOrbigny, 1835) foram encontradas na Vila do Abraão, sendo este o primeiro registro dessas espécies para a Ilha Grande, Angra dos Reis, Rio de Janeiro. A introdução provavelmente ocorreu após 2004, como conseqüência do despejo de água de aquário. A possível dispersão destas espécies para outros corpos dïágua, efeitos sobre as espécies nativas e conseqüências para saúde pública são tópicos discutidos. Em relação a M. tuberculatus, este é o primeiro registro para uma área insular do Brasil. A introdução recente destas espécies oferece uma oportunidade única para o monitoramento de espécies introduzidas e para uma melhor compreensão do processo de invasão, especialmente de M. tuberculatus, em córrego insular do sudeste do Brasil.