Based on literature review and malacological collections, 168 native freshwater bivalve and five invasive species have been recorded for 52 hydrographic regions in South America. The higher species ...richness has been detected in the South Atlantic, Uruguay, Paraguay, and Amazon Brazilian hydrographic regions. Presence or absence data were analysed by Principal Coordinate for Phylogeny-Weighted. The lineage Veneroida was more representative in hydrographic regions that are poorer in species and located West of South America. The Mycetopodidae and Hyriidae lineages were predominant in regions that are richest in species toward the East of the continent. The distribution of invasive species Limnoperna fortunei is not related to species richness in different hydrographic regions there. The species richness and its distribution patterns are closely associated with the geological history of the continent. The hydrographic regions present distinct phylogenetic and species composition regardless of the level of richness. Therefore, not only should the richness be considered to be a criterion for prioritizing areas for conservation, but also the phylogenetic diversity of communities engaged in services and functional aspects relevant to ecosystem maintenance. A plan to the management of this fauna according to particular ecological characteristics and human uses of hydrographic regions is needed.
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 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.
Bivalves are important components of freshwater ecosystems; however, they are also one of the most threatened animal groups, especially members of the order Unionida. The main threats to freshwater ...bivalves are habitat modification and invasive species. Protected areas are a common way to minimize impacts and preserve native species, but they are rarely designated with a focus on freshwater invertebrates.
The main goal of this article was to describe the distribution of freshwater bivalves in the state of Rio de Janeiro, and the relationship between these species and bioclimatic areas, land use and protected areas.
Five native and two invasive bivalve species have been reported in Rio de Janeiro. They occur mainly in bioclimatic areas related to the Paraíba do Sul River and Campista Lowlands. The few records of bivalves inside protected areas are in areas of sustainable use that offer a lower level of protection, and frequently in sympatry with invasive bivalves.
Thus, the established protected areas in Rio de Janeiro are not adequately effective for freshwater bivalve conservation, and some species remain under threat even within them. Freshwater bivalves thus remain largely unprotected in the state.
The development of new protected areas and management plans should consider other faunal groups that are usually ignored, such as freshwater bivalves, to achieve more inclusive and effective protection.
During a pilot survey, sponges and mollusks were sampled from the bottom of the middle Xingu River (rapids) and lower Xingu River (ria) via hand-picking in shallows and trawling and surface-supplied ...dives in deeper waters. The survey revealed a benthic community composed of eight sponge species in four genera and three families, and added six species to the Xingu Basin fauna. Sponges exhibited distinct variation in body shape corresponding to local environmental conditions such as water depth, current velocity and available substrates. Sponges inhabiting rocky bottoms in swift currents (rapids) typically formed crusts. Those in the deeper, calmer waters of the ria attained massive and elaborate forms while attached to infaunal bivalves. Oncosclera navicella and Drulia cristata exhibited crusts and massive forms as adaptations to rapids and ria, respectively. In the middle to lower Xingu, sponges encrusted the shells of eleven species of bivalves (seven infaunal, three epifaunal, and one infaunal/epifaunal) and one infaunal/epifaunal gastropod. Bivalves provide key substrates for supporting sponges above the sand, mud and detritus of the Xingu ria. Potential impacts of the Belo Monte Dam complex on the sponge fauna of the middle Xingu rapids are discussed.
Rheodreissena Geda et al. 2018, a recently described genus of Dreissenidae, is represented by living species that inhabit inland freshwaters of Brazil and Venezuela. The type species of Rheodreissena ...is R. hoeblichi (Schütt 1991a) described from the lower Orinoco basin, Venezuela. Three species are added in this study: R. lopesi (Alvarenga & Ricci, 1989) from the Tocantins and Xingu basins; R. cordilineata n. sp. from the Madeira, Trombetas and Xingu basins, and R. xinguana n. sp. from the Tapajós and Xingu basins. Those three species are recorded from Volta Grande, the stretch of the Xingu River impacted by the Belo Monte dam complex. All Rheodreissena typically attach in shallow clusters to clean, rocky substrates associated with rapids in the main channels of large clear water rivers. Species of Rheodreissena are distinguished by aspects of shell morphology and soft anatomy that presumably reflect adaptations to a rheophilic lifestyle. In Xingu and Tocantins populations of Rheodreissena, larval broods were observed in the ctenidial (R. lopesi and R. xinguana) and pallial cavities of females (all three species). Examples of pallial broods included a few prodissoconch-1 (D-shaped) larvae in R. xinguana n. sp., 24 larvae/juveniles representing three different stages (prodissoconch 1 and 2, dissoconch) in R. cordilineata and up to 65 larvae/juveniles representing the same three stages in R. lopesi. In R. cordilineata and R. lopesi, the prodissoconch is attached to the parental mantle via a modified velum (adhesivelum), and dissoconchs attain lengths of 800 µm and 987 µm, respectively. For larvae brooded in the pallial cavity, a biphasic growth pattern was demonstrated statistically in R. lopesi and determined by observation in R. cordilineata. Juveniles are presumably released gradually into the environment at the crawl-away dissoconch stage. Biphasic brooding (ctenidial and pallial) was previously described for the European cave-dwelling dreissenid species Congeria kusceri; differences between brooding in Congeria and Rheodreissena are noted. Various morphological and lifehistory traits of species of Rheodreissena are summarized and compared to the other living species of Dreissenidae: Mytilopsis leucophaeata, M. sallei, Dreissena polymorpha, D. rostriformis (ex. bugensis), and the three nominal species of Congeria.
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.
The Ilha Grande National Park, Paraná, Brazil, is located in the Upper Paraná River and has characteristics typical of a floodplains. This protected area includes lagoons connected and disconnected ...to the Paraná River, although the latter also connect during periods of high water level, thus composing a heterogeneous group of lacustrine environments. The enormous potential the flora and fauna diversities are still little known to the region, as can be seen through benthic invertebrates, inclunding bivalves mollusks. The granulometric composition of these floodplain lagoons was formed mainly by mud and very fine sand. Furthermore, organic matter composition was predominantly of fine particulate. The other abiotic factors differed from lagoons located within the island of the park to those located in the left margin of Paraná River. The results demonstrated the importance of abiotic factors such as the physical composition of granulometric texture, organic matter and macrophyte banks, to the establishment of bivalves in these floodplain lagoons. We recorded bivalves of Pisidium (native), Diplodon (native), and Corbicula (invasive). The highest values of Diplodon sp. density were observed at São João/C lake, for Pisidium sterkianum (Pilsbry, 1897) at São João/M lake, and to Jatobá/C lagoon with high density of invasive species Corbicula fluminea (Müller, 1774). This study to obtain conduct the first records of freshwater bivalves in floodplains lagoon in the Ilha Grande National Park, and provides contributions to better understanding the ecology of these mollusks. The recording of native species in the region of Upper Paraná River floodplain after a lomg period without new records, demonstrated the importance of protecting the lagoons of the Ilha Grande National Park as they can be a possible refuge to some species of native freshwater bivalves.
O Parque Nacional de Ilha Grande (Paraná, Brasil) é localizado no Alto Rio Paraná e apresenta características típicas de uma planície de inundação. Essa área de proteção ambiental inclui uma heterogeneidade de ambientes lacustres, dentre estes lagoas conectadas e não conectadas ao rio Paraná. Os enormes potenciais de diversidade tanto de flora quanto de fauna são ainda pouco conhecidos para o local, como para os invertebrados bentônicos, e dentre eles, os moluscos bivalves. A composição granulométrica das lagoas foi constituída basicamente de sedimentos mais finos, como lama e areia muito fina, e a matéria orgânica composta predominantemente por partículas finas. Também observamos diferenças espaciais nos fatores limnológicos, separando as lagoas situadas dentro da ilha do parque, das contidas na margem esquerda do rio Paraná. Esses dados demonstraram a importância dos fatores físicos como composição da textura granulométrica, matéria orgânica e bancos de macrófitas para o estabelecimento dos bivalves nesses ambientes. Registramos bivalves de Pisidium (nativa), Diplodon (nativa) e Corbicula (invasora). Os maiores valores de densidade média foram observados para Diplodon sp. na lagoa São João/C, para Pisidium sterkianum (Pilsbry, 1897) na lagoa São João/M, e para a espécie invasora Corbicula fluminea (Müller, 1774) na lagoa Jatobá/C. Esse estudo teve como objetivo realizar o primeiro levantamento de bivalves límnicos em lagoas de inundação do Parque Nacional da Ilha Grande, além de fornecer subsídios para melhor compreensão da ecologia desses moluscos. O registro de espécies nativas, após um longo período sem ocorrência na região da planície de inundação do alto rio Paraná, demonstrou a importância da proteção das lagoas do Parque Nacional de Ilha Grande para a manutenção dos mesmos, podendo assim ser um possível refúgio para algumas espécies de bivalves límnicos nativos.
The glochidia of Diplodon (Diplodon) suavidicus (Lea, 1856), D. (D.) obsolescens F. Baker, 1914, Diplodon (Rhipidodonta) hylaeus (d'Orbigny, 1835), Prisodon obliquus Schumacher, 1817, Paxyodon ...syrmatophorus (Meuschen, 1781), Triplodon corrugatus (Lamarck, 1819, and Castalia ambigua Lamarck, 1819 were redescribed based on comparisons of external morphology and morphometric measurements of larval shells. The outline of the glochidial valves was classified into three types. The morphological comparison was based on light and scanning electron microscopy. Details of the shell, hooks and external sculpture allowed a redescription of the larvae, transferring D. suavidicus and D. obsolescens to the subgenus Diplodon and, within the Prisodontini, the genus Triplodon Spix, 1827 was separated from Prisodon Schumacher, 1817 and Paxyodon Schumacher, 1817. The glochidium of Prisodon obliquus is described for the first time. The larvae of the latter species and those of Paxyodon syrmatophorus present projections on the external sculpture in the form of spikes that have not yet been seen in the larvae of other South American Hyriidae. This unique ornamentation indicates closer proximity of Prisodon obliquus to Paxyodon syrmatophorus, a result also supported by multivariate analysis that allowed separation of the glochidia of the different species, using morphometric measurements such as length, height, length of the dorsal line and angle of obliquity formed between the position of the base edge in relation to the center of the dorsal line. Considering the angle of obliquity, the glochidium of Castalia Lamarck, 1819 was observed to diverge greatly in relation to those of other genera. The sampling dates of adults containing glochidia in the marsupium and an illustrated glossary are provided.
We redescribe type specimens of two freshwater mussels from Brazil, Diplodon ellipticus Spix in Wagner, 1827 and Diplodon expansus (Kuster, 1856), focusing on previously unnoticed diagnostic ...conchological aspects in a brief taxonomical review. The first species, represented by one shell previously considered to be lost, was recently rediscovered in the collection of the Zoologische Staatssammlung Munchen, Germany, and identified as the figured holotype. Material of the second species, deposited at the Charpentier Collection at the Musee de Zoologie Lausanne, Switzerland, was discovered to be a syntype series. The lectotype and paralectotypes of D. expansus were selected.
The ceramic substrate (21cm in length, 6cm in width and 1.3cm in depth) was tested for the Limnoperna fortunei population, sampling at two localities in the Jacuí delta (Jacuí Canal (Canal do Jacuí – ...CJ) and Port Docks (Cais do Porto – PO)) in Rio Grande do Sul state, Brazil. The individuals were quantified through the superimposition of a squared (1cm2) and segmented (sI, sII e sIII) sheet on the substrate. Using Kruskal-Wallis and Mann-Whitnney, the recruit and adult average densities were compared in each segment, surface (smooth and pipe-shaped) and sampling locality (α = 0.05). In CJ, the extreme and intermediate (adult) segments differed statistically (p < 0.0001), as well as the ceramic substrate surfaces (recruits) (p = 0.04). The recruit and adult densities between the CJ and PO localities also differed between themselves (p < 0.0001). The method was efficient for the invasive population sampling.
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