RESUMO Diplodon granosus foi um dos primeiros bivalves de água doce descritos para a América do Sul. Contudo, o status dessa espécie foi confuso por um longo tempo, recebendo diferentes tratamentos taxonômicos. Neste estudo, apresentamos a redescrição da concha, assim como novos dados da anatomia das partes moles, e informações acerca da distribuição e conservação desta espécie raramente avistada. A concha é fina, não-inflada; a macroescultura é composta somente por grânulos que cobrem toda a concha, e não formam raios; a microescultura é composta por espinhos curtos. Nas partes moles, destacamos as poucas, fracas e irregularmente distribuídas conexões interlamelares da demibrânquia externa, assim como algumas características do estômago, como a tiflossole menor distalmente aumentada. Existem registros de D. granosus em uma grande área da América do Sul, da Guiana até a Argentina. Contudo, muitas destas ocorrências são relacionadas com outras espécies, estando D. granosus restrita às bacias dos rios Amazonas e Orinoco, e a rios costeiros entre essas duas bacias. Apesar desta aparente ampla distribuição, a espécie ocorre em habitats específicos, principalmente riachos (igarapés), resultando em uma distribuição fragmentada. Assim, qualquer modificação nestes ambientes pode ameaçar esta espécie.

ABSTRACT 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.

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.

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 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.

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.

Introduction Schistosomiasis is a parasitic disease of public health concern in Brazil, and the construction of hydroelectric dams, in addition to increasing permanent human settlement and tourism, has created conditions suitable for the establishment of mollusks that can transmit schistosomiasis. Such areas require a number of actions to prevent the establishment of schistosomiasis. This paper reports on a freshwater malacological survey carried out in the geographical area of the Manso Power Plant. Methods Mollusks were collected in 18 municipalities in the State of Mato Grosso between February 2002 and February 2004 (qualitative study) and from April 2009 to February 2011 (quantitative study). Results Thirty-one species of mollusks were collected, including newly recorded species (Antillorbis nordestensis and Burnupia ingae). In addition, the geographic distributions of known species, including Biomphalaria straminea, a snail vector of Schistosoma mansoni, were expanded. A total of 4,507 specimens were collected in the APM Manso reservoir (Usina Hidrelétrica de Aproveitamento Múltiplo de Manso) during the quantitative study, and Biomphalaria amazonica was found in six of the 10 localities analyzed. The Afroasiatic species Melanoides tuberculata, introduced after February 2009, was the dominant species (relative abundance 94.96%). Conclusions The study area is epidemiologically important due to the occurrence of B. straminea and B. amazonica, which are vectors of schistosomiasis, and M. tuberculata, a snail host of Centrocestus formosanus, which is responsible for centrocestiasis transmission. Observations of M. tuberculata and the exotic freshwater clams Corbicula fluminea and Corbicula largillierti raise concerns about biodiversity.

We conducted a study on shell morphology variation among three populations of Happiella cf. insularis (Boëttger, 1889) inhabiting different areas (Jararaca, Caxadaço, and Parnaioca trails) at Vila Dois Rios, Ilha Grande, Angra dos Reis, state of Rio de Janeiro, Brazil. Linear and angular measurements, shell indices representing shell shape, and whorl counts were obtained from images drawn using a stereomicroscope coupled with a camera lucida. The statistical analysis based on ANOVA (followed by Bonferroni's test), Pearson's correlation matrix, and discriminant analysis enabled discrimination among the populations studied. The variable that most contributed to discriminate among groups was shell height. Mean shell height was greatest for specimens collected from Jararaca, probably reflecting the better conservation status of that area. Good conservation is associated with enhanced shell growth. Mean measurements were smallest for specimens from Parnaioca, the most disturbed area surveyed. Mean aperture height was smallest for specimens from Parnaioca, which may represent a strategy to prevent excessive water loss. Discriminant analysis revealed that the snails from Jararaca differ the most from snails collected in the two other areas, reflecting the different conservation status of these areas: shells reach larger sizes in the localities where the humidity is higher. The similarities in shell morphology were greater between areas that are more similar environmentally (Caxadaço and Parnaioca), suggesting that conchological differences may correspond to adaptations to the environment.

Pequenas populações de Melanoides tuberculatus (Müller, 1774) e de Biomphalaria tenagophila (d´Orbigny, 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 d´água, 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.

Small populations of Melanoides tuberculatus (Müller, 1774) and Biomphalaria tenagophila (d´Orbigny, 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.

A survey of the Ilha Grande land snails was carried out in order to compare the diversity and similarity among two regions of secondary Atlantic Rain Forest. The diversity was estimated using the richness and the equitatibility; the alpha diversity was calculated using the Simpson index (γ). The Sörensen and Jaccard indexes were used to calculate the similarity. A quantitative survey of two 600 m² area, one in each studied region, recorded 336 individuals snails distributed in 23 species and 13 families. The region with more altered secondary forest showed higher richness (17) and diversity (γ = 3,6) than the region more preserved (richness = 14; γ = 2,78), but, the same equitatibility (0,20). The similarity was medium by Jaccard index (IJ = 0,52) and low by Sorensen index (IS = 0,15). These differences could be explained by the dominance of Subulinidae (four species and 117 specimens) in the more altered region and Systrophiidae in the more preserved (four species and 97 specimens).

A study on the morphology of the muscular and reproductive systems of Anisancylus obliquus (Broderip & Sowerby, 1832) based on specimens from Chile is presented. Differences are observed in the number of folicules of the ovotestis and prostata when comparing them with specimens from Brazil (chilean specimens: ovotestis = 28 to 32; prostata = 3 to 5; brazilian specimens: ovotestis = 20 to 21; prostata = 6 to 8). In the muscular system, the right aductor muscle scar is often longer than in brazilian specimens. The general morphology of muscular and reproductive systems is similar to that observed to Uncancylus concentricus (d'Orbigny, 1835) and Gundlachia dutrae Santos, 1994 (V-shaped adhesive area; single right anterior muscle with elongated moon-shaped scar; ejaculatory complex with projected ejaculatory duct) and differs from G. ticaga (Marcus & Marcus, 1962), G. radiata (Guilding, 1828) and Hebetancylus moricandi (d'Orbigny, 1837) (elongated adhesive area; double right anterior muscle with rounded or oval-shaped muscle scar and ejaculatoiy complex without projected ejaculatory duct). Differences are also observed when comparing them with Ancylus fluviatilis Müller, 1774 where the right muscle scar is continuous with the posterior one, whereas A. obliquus shows three well defined muscle scars. The ejaculatory system of A. fluviatilis presents flagellum duct and ejaculatory duct opening apart into the sheath; there are penis, prepuce with muscular pillars and a muscular flagellum, whereas A. obliquus shows the flagellum duct and ejaculatory duct reaching the sheath together; there are not penis and muscular pillars on prepuce; the flagellum is glandular. These differences shows A. obliquus and others neotropical pateliforms basommatophorans are not closely related to european Ancylus.

A description of Laevapex vazi n. sp. based on 8 specimens collectec in Ourinhos, state of São Paulo, is presented. Shell thin, diaphanous, with a light brown periostracum and moderately elliptical opening. Apex not pointed, smooth, situated on the right posterior region of the shell, inclined to the right often reaching the edge of the shell or extending beyond it. Concentric lines clearly visible; radial striation not visible or when perceptible very thin, here and there. Ratios: shell width/shell lenght = 0,60 - 0,67 (mean = 0,63); shell height/shell length = 0,50 - 0,61 (mean = 0,55); shell height/shell width = 0,33 - 0,40 (mean = 0,35). Body of normal ancylid type; mantle pigmentation concentrated on the left side; three muscles are seen: a round posterior one on the left side, an elliptical muscle on the right anterior side and an almost almond-shaped one on the left anterior side. Tentacles with a medium core of black pigment. Pseudobranch two-lobed and folded, the dorsal lobe smaller than the vetral one. Ovotestis with 20 unbranched diverticula, around a short collecting canal. Ovispermiduct with an enlargement with several round outpocketings constituting the seminal vesicle. Carrefour as a round sac. Albumen gland almost cylindrical with several acinous diverticula. Elongated nidamental gland continous with the galndular wall of the uterus; uterus flattened and thin-walled. Spermathecal body almost rounded. Pear-shaped prostate without diverticula. Penial complex without flagellum but with well-developed ultra-penis and penis. Jaw horseshoe shaped. Radular forma 20.1.20; raquidian tooth quadricuspid, asymmetrical. The genus Laevapex Walker, 1903 is recorded for the first time in Brazil. It is easily distinguished from South American Gundlachia Pfeiffer, 1849 by its penial complex. Laevapex vazi is dedicated to Dr. Jorge Faria Vaz, from SUCEN-SP, who have been sent to me the specimens.