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In Brazil, Anodontites trapesialis is a mussel species that occurs spontaneously in fish breeding sites. This species feeds on the remains of cultural treatments of other aquaculture species. The objective of the work is to understand the bromatological composition of mussel A. trapesialis. Individuals were selected to compose three samples of 500 g each of A. trapesialis for chemical composition, with viscera and viscera + shells being evaluated. The species presented 40.42 to 62.76 g of viscera per individual with a moisture content of 5.16% for viscera + shells and 86.5% for viscera. The mussel contains 42.6 and 12.96% crude protein, 3.16 and 1.76 of ether extract, 0.76 and 2.5% of crude fiber for viscera and viscera + shells. The total digestible nutrients were 74.16 and 36.96% for viscera and viscera + shells and 18.43 and 52.83% of mineral material for viscera and viscera + shells. A. trapesialis has relevant characteristics in its chemical composition as high protein content that gives the species potential for the human, animal, and other byproducts production.

In 2012, a severe drought struck the southeastern of Brazil compromising the Paraná River Basin reservoirs. Here, we described how this climatic event promoted a massive mortality of the giant freshwater mussel Anodontites trapesialis in Furnas reservoir and reported the consequences of this phenomenon. In November 2012, three quarters of 100 m2 were sampled in this reservoir, where 812 dead shells of A. trapesialis were analyzed and measured (33 ˫ 133 mm). The species showed an aggregated distribution with high density ( X ¯: 1.0 - 5.5 ind/m2). Despite the massive mortality detected in field, it was possible to find living specimens in a small channel in the studied area, allowing the species to survive the water level fluctuations. Large adult individuals (100 ˫ 124 mm) were more affected by drought than juveniles, accounting for about 90% of the dead mussels analyzed. Two years after the massive mortality event, water level was not reestablished and a terrestrial succession (with elevations in the concentration of organic matter and calcium in sediment) was observed in the studied area. We verified that the damming associated with extreme climatic events affect negatively the populations of A. trapesialis and should be faced as a conservationist problem.

Determining how, when, and why energy allocation occurs based on different life history traits, provides core knowledge for understanding evolution, ecology, and conservation of populations. We assumed that, in seasonal environments, Anodontites trapesialis, a common freshwater mussel in the Pantanal wetland, has to time its maturation, its larvae incubation time, and adjusts its breeding strategy seasonally. From histological analyses of gametes, larval count, and marginal increment of the shell rings, we present information about phenology and growth strategies to investigate the influence of environment and reproductive period on growth. We determined for the first time, asymptotic maximum size and longevity for this mussel. This species is a functional hermaphrodite, with maturation and spawning starting at the end of the flood period, when the water begins to recede and fishes return to the main river channel. The larvae, lasidium in this case, disperse on host fishes at this time. As we predicted, the flood pulse is the main regulatory factor to the growth patterns and reproductive period establishment. The species’ life history traits are discussed in the context of life history theory as adaptive responses to the dynamic balance imposed by the seasonality of the Pantanal.

The objective of this paper is to review the current state of our knowledge of freshwater bivalve diversity and evolution in order to identify some of the “Great Unanswered Questions” in the field. Twenty-one bivalve families have been attributed to fresh waters, but only 16 actually live and reproduce in inland waterways. Of 1209 species of freshwater bivalves, 1178 (97%) belong to eight primary freshwater families: Unionidae, Margaritiferidae, Hyriidae, Mycetopodidae, Iridinidae, and Etheriidae (all Unionoida), Sphaeriidae, and Cyrenidae (both Veneroida). The remaining 31 species represent secondary freshwater lineages of predominantly brackish/marine bivalve families. The global geographical patterns of freshwater bivalve richness are discussed, and an appendix detailing the families, genera, and species of freshwater bivalves is provided.Although the primary freshwater bivalve families represent at least three independent radiations from marine into inland aquatic habitats, these lineages have converged on similar adaptations to life in a flowing hypoosmotic medium. For example, all have abandoned broadcast spawning and planktonic veligers. Phylogenetic studies of the Unionoida, Sphaeriidae, and Cyrenidae have also converged on a suite of common challenges: outgroup issues, biased ingroup taxon and character sampling, and atypical modes of genetic inheritance that uncouple gene trees from species trees. The recent phylogenetic literature on the three primary radiations is reviewed, emphasizing areas in need of research. Ample opportunities exist in freshwater bivalve research but progress is hindered by the limited numbers of researchers and students in the field.

costulata, Unio (Monocondylea), J. Moricand, 1858: 453, pl. 15 fig. 1. Type locality: Brésil. Syntypes: MHNG-INVE-91234 (1) (Unionidae) [Figs 50-53]. – Remarks. Moricand junior wrote “j’en ai reçu seulement deux individus”, which is interpreted as two doublets. Only one specimen (doublet), however, could be found in the collection. The specimen was labelled as having been revised by Haas in 1930., Published as part of Breure, Abraham S. H. & Tardy, Emmanuel, 2016, From the shadows of the past: Moricand senior and junior, two 19 th century naturalists from Geneva, with their newly described taxa and molluscan types, pp. 113-138 in Revue suisse de Zoologie 123 (1) on page 120, DOI: 10.5281/zenodo.46292

reticulata, Lavoisiera, S. Moricand, 1847: 170, pl. 99. Type locality: [Brazil, Bahia] ad Igregia Velha [Blanchet] (Melastomataceae)., Published as part of Breure, Abraham S. H. & Tardy, Emmanuel, 2016, From the shadows of the past: Moricand senior and junior, two 19 th century naturalists from Geneva, with their newly described taxa and molluscan types, pp. 113-138 in Revue suisse de Zoologie 123 (1) on page 118, DOI: 10.5281/zenodo.46292

reticulata, Unio (Monocondylea), J. Moricand, 1858: 454, pl. 15 fig. 2. Type locality: Amazone. Syntypes: MHNG-INVE-91236 (2) (Unionidae) [Figs 37-40]. – The specimens were accompanied by a label stating “Revised Haas 1930”., Published as part of Breure, Abraham S. H. & Tardy, Emmanuel, 2016, From the shadows of the past: Moricand senior and junior, two 19 th century naturalists from Geneva, with their newly described taxa and molluscan types, pp. 113-138 in Revue suisse de Zoologie 123 (1) on page 122, DOI: 10.5281/zenodo.46292

The maintenance of the freshwater mussels' community in lakes is determined by abiotic factors at the local scale and at regional scale by interspecific relations between the larvae of bivalves and fish host. Whereas the distribution pattern at local scale, our goal was to understand the abundance and community composition of bivalves and relate the environmental agents structuring this community. We sampled 20 lakes in the floodplain of the Cuiabá River using a standardized method of sampling. To evaluate the effect of environment on the community we applied multivariate inferential analyses. We found 1.143 individuals alive belonging into six species distributed at the family Hyriidae, Mycetopodidae, Sphaeridae and Corbiculidae. The results showed that in the Pantanal the bivalve assemblage structure is influenced locally by organic matter and particle size, variables that reflect the intense interactions between water-sediment. However it is important to emphasize that these environmental characteristics are the result of the dynamics of this system which is dependent on the flood pulse, a regional factor. A manutenção da comunidade de bivalves límnicos em lagos é determinada por fatores abióticos em escala local e em escala regional pelas relações interespecíficas entre as larvas do bivalve e o peixe hospedeiro. Considerando o padrão de distiribuição em escala local, nosso objetivo foi conhecer a abundância e a composição da comunidade de bivalves e relacionar os agentes de estruturação desta comunidade. Foram amostrados 20 lagos na planície de inundação do rio Cuiabá usando método padronizado de amostragem. Para avaliar o efeito dos fatores abióticos sobre a comunidade aplicamos análises multivariadas inferenciais. Encontramos 1.143 indivíduos vivos, distribuidos em seis espécies pertencentes às famílias Hyriidae, Mycetopodidae, Sphaeridae e Corbiculidae. Os resultados demonstraram que no Pantanal, a estrutura da assembléia de bivalves é influenciada localmente pela matéria orgânica e granulometria, variáveis que refletem as intensas interações entre água-sedimento. No entanto é importante ressaltar que tais características ambientais são resultantes da dinâmica deste sistema o qual é dependente do pulso de inundação periódico, um fator de escala regional.

The aim of this work was to register the occurrence of Anodontites tenebricosus (Bivalvia: Mycetopodidae) in the Sapucaí river basin, municipality of São Joaquim da Barra, São Paulo state, Brazil, associating its occurrence to the environment in which they are found, besides providing conchological data to contribute to the identification of the species. Fifty one specimens of Anodontites tenebricosus were studied regarding their conchological and morphometrical aspects. Strong correlations were found between the morphometric variables, the correlation between 'length and height of the shell' being the most significant. The characteristics of the shells of A. tenebricosus found in the Sapucaí river basin resemble the descriptions of the species found in the literature; therefore, we are able to expand the area of occurrence of the species for the state of São Paulo.

Microprojections of unionoid shells are virtually unstudied but could be important characters for resolving questions on the phylogeny and ecology of these bivalves. By investigating 26 unionoid and three species of their closest living relatives, the Trigonioida, using scanning electron microscopy, we identified three types of periostracal microprojections. (1) Microridges were present only in one species from each of the two unionoid families Mycetopodidae (Anodontites trapesialis) and Iridinidae (Chambardia bourguignati) and may represent a synapomorphy for the mycetopodid-iridinid clade. In A. trapesialis, microridges were additionally equipped with (2) flag-like projections (microfringes), possibly a synapomorphic character for the Mycetopodidae. Examination of partially bleached specimens indicated that both microridges and microfringes are predominantly or purely organic. In contrast, previously undescribed (3) spicule-like spikes represent calcifications within the periostracum. These were found in 20 of the 29 species and four of the six unionoid families. Spikes were particularly large and abundant in umbonal (juvenile) shell regions and species characteristic of fast-flowing habitats. These structures may thus serve in protecting the periostracum and shell underneath, and ⁄ or stabilizing life position by increasing shell friction. Microfringes and microridges, on the other hand, possibly aid in the orientation of the mussel within the sediment.

The term freshwater bivalve is very inclusive and not very informative. There are representatives of at least 19 families that have at least one representative living in freshwater. This suggests at least 14 different invasions of freshwater. At least nine families have small to large radiations in the freshwater environment: Corbiculidae, Sphaeriidae, Dreissenidae, and the unioniforme families: Hyriidae, Margaritiferidae, Unionidae, Etheriidae, Iridinidae, and Mycetopodidae. The unioniforme families contain at least 180 genera and about 800 species. This order is characterized by the unique parasitic larval stage on the gills, fins or the body of a particular host fish. This order of freshwater bivalves is suffering a very high rate of extinction, with about 37 species considered presumed extinct in North America alone. The level of endangerment and extinction facing these animals is primarily the result of habitat destruction or modification.

O ciclo reprodutivo de Anodontites trapesialis foi estudado entre os meses de maio de 1998 a abril de 1999. Análises quantitativas dos elementos celulares revelaram que a espécie é exclusivamente hermafrodita com folículos masculinos e femininos separados. A gametogênese é contínua com picos de maturação e eliminação de gametas durante a estação seca. A ovogênese tem seu período de maturação máxima em abril e maio, momento em que óvulos maduros são observados preenchendo os folículos e gonoductos. A espermatogênese foi reconhecida por uma fase proliferativa com células em desenvolvimento e apresentou seu período de maturação entre abril e julho. Estas células se diferenciaram dando origem às mórulas espermáticas e espermatozóides livres, organizando a série espermática radial. Durante o período de liberação dos gametas, a maioria dos folículos apresentou agregados de espematozóides formando esferas espermáticas as "spermballs", as quais caracterizam a espécie como espermatozeugmata.

Com base no exame de exemplares de moluscos bivalves depositados em várias coleções científicas locais e internacionais, procedentes da bacia do rio dos Sinos, estado do Rio Grande do Sul, Brasil, apresentou-se uma revisão taxomica com diagnoses e chave dicotômica. Registram-se dez espécies de Hyriidae, dez de Mycetopodidae, três de Corbiculidae - duas exóticas: Corbicula largillierti (Philippi, 1844) e C. fluminea (Müller, 1774) -, três de Sphaeriidae e uma exótica de Mytilidae, Limnoperna fortunei (Dunker 1857). Restringiu-se a localidade tipo de Anodontites iheringi (Clessin, 1882) ao rio Paranhana, no município de Igrejinha (29º36'S e 50º50'W). As espécies foram distribuidas de acordo com as diferentes zonas do rio (superior, média e inferior). Ten species of Hyriidae, ten of Mycetopodidae, three of Corbiculidae - two exotic: Corbicula largillierti (Philippi, 1844) and C. fluminea (Müller, 1774) -, three Sphaeriidae and one exotic Mytilidae, Limnoperna fortunei (Dunker, 1857), were taxonomically revised with diagnosis and identification key for the Sinos River Basin, State of Rio Grande do Sul, Brazil. Voucher specimens of several scientific collections were examined. The type locality of Anodontites iheringi (Clessin, 1882) is presently restricted to Paranhana River, Municipality of Igrejinha (29º36'S and 50º50'W). Species distribution according to the river zones (high, middle and low) is presented.

The Palaeoheterodonta is a diverse clade consisting of the freshwater bivalve order Unionoida and its marine sister group, Neotrigonia. Neotrigonia is the sole surviving genus of the Trigonioida, known from only six species in Australian waters. Unionoids (freshwater mussels), in contrast, are widespread on all continents except Antarctica and are represented by c. 900 species. Discussion is biased towards the freshwater mussel condition, but Neotrigonia is crucial as a ‘living fossil’ for establishing the plesiomorphic states of unionoid synapomorphies. Neotrigonia retains many of the characters of the ancestral heteroconch. Our object is to provide evidential support for the natural classification of the extant Palaeoheterodonta. A supermatrix of 50 taxa and 1183 characters was constructed from 62 previously published DNA sequences of mitochondrial cytochrome oxidase subunit I (COI) and 28S nuclear ribosomal DNA, 15 novel sequences, and 59 morphological characters. Published COI sequences for Coelatura aegyptiaca, Pseudomulleria dalyi, and Obliquaria reflexa were treated as potentially problematic because of their inconsistency under different methodological assumptions and conflict with other datasets. Each partition was analysed under the criterion of parsimony separately and in combined analyses; analyses were run both with and without the problematic sequences. From our ‘combined evidence’ topology (with problematic sequences excluded), the Unionoida is monophyletic on the basis of eight synapomorphies, including larval parasitism, brood protection, and restriction to freshwater. The order is composed of six families in two superfamilies, Unionoidea and Etherioidea: ((Unionidae + Margaritiferidae) + (Hyriidae + (Etheriidae + (Mycetopodidae + Iridinidae)))). The morphological synapomorphies of these taxa are discussed with an emphasis on both the diagnosing of taxa and highlighting areas of ambiguity and missing data. Three appendices provide descriptions of the morphological characters (Appendix 1), a diagnosis of apomorphies for all branches of the phylogeny (Appendix 2), and a family-level classification of the extant Palaeoheterodonta, including a complete synonymy (Appendix 3). © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 148, 343–394.

Burrowing rate index, diurnal variations in heart rate and heart rate alterations associated with behavioral patterns were studied in Anodontites trapesialis from the Pardo River (PR) and the Galo Bravo Dam (GBD). In both populations the pattern immobile/buried was associated with the lowest (basal) values of heart rate, which increase significantly during burrowing remaining steady in its phases I and II and at the first 10 min of phase III. A decrease in the frequency of digging cycles was significantly correlated with the gradual decrease in heart rate during the phase III of burrowing. Nevertheless, mussels from PR burrow faster than those of GBD and possess higher values of basal heart rate which present a diurnal variation with the higher values occurring during the light phase. Yet, the basal heart rate in mussels from GBD remained stable over the course of 24 h. Also, the increase in heart rate associated with burrowing was higher in mussels from PR and compatible with the highest burrowing index previously detected. Since mussels possess a plastic phenotype it is probable that the cited functional differences are phenotypic adaptations, but we cannot exclude the possibility of these adaptations being genotypic in nature.

Based on optical and SEM microscopic observations, the projections of the outer surface of the periostracum and inner micro-structures of the shell are described and redefined. The outer surface of the periostracum is practically smooth in both species. Considering a mesoscopic view of the periostracum, A. trapesialis (Lamarck, 1819) presents regular corrugations in the form of radial sequences of arches on the disk region, isolated rays or horizontal sequences of rays on the anterior lower region. A. elongatus presents corrugations formed by series of oblique arches on the disc and oblique rays on the carina. Under SEM, micro ridges were more evident in A. elongatus, but a wide diversity of shapes and patterns of micro fringes were observed in A. trapesialis, especially in young individuals. Considering the profile of the shell layers, the periostracum is relatively thin and apparently simple in A. trapesialis and thinner in A. elongatus. The prismatic layer is thick in both species, consisting of a single series of elongated prisms and wedge-shaped prisms close to the outer surface. The nacreous layer consists of very fine lamellae without pattern or with a slight staircase-like; in A. elongatus this layer is divided by a laminar inclusion of conchiolin. The fringes are abundant and diversified in A. trapesialis, a species less resistant to desiccation due to the presence of a wide intervalvar gap. The existence of a greater density of micro fringes and spikes in juveniles may be related to the orientation of the animal in order to search for an ideal site for development or for escape from regions subject to seasonal droughts, like Pantanal.Projeções da superfície externa do perióstraco e micro estruturas da concha foram redefinidas com base na microscopia óptica e eletrônica de varredura. A superfície do perióstraco é praticamente lisa em ambas espécies. Sob vista mesoscópica, A. trapesialis (Lamarck, 1819) apresenta corrugações regulares formando seqüências radiais de arcos na região do disco, raios isolados ou seqüências horizontais na região antero inferior. A. elongatus (Swainson, 1823) apresenta séries de arcos organizados radialmente no disco e arcos oblíquos na carena. Sob MEV, as micro estrias são mais evidentes em A. elongatus; A. trapesialis apresenta micro franjas muito diversas quanto a forma e padrão, principalmente em jovens. Considerando as camadas da concha, o perióstraco é mais fino em A. elongatus. A camada prismatica é espessa nas duas espécies, com uma série única de prismas alongados e em forma de cunha próximo à superfície externa. A camada nacarada compõe-se de lamelas muito finas, sem padrão ou do tipo escadaria; em A. elongatus esta camada é dividida por uma inclusão laminar de conchiolina. As franjas são abundantes e diversificadas em A. trapesialis, espécie menos resistente à dessecação devido à presença de ampla fresta intervalvar. A ocorrência de uma grande densidade de micro franjas e espinhos nos juvenis, estaria relacionada à orientação do animal na busca por local ideal ao seu desenvolvimento ou para escapar das regiões sujeitas às secas sazonais, como o Pantanal.

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., Facultad de Ciencias Naturales y Museo

The anatomy of Anodontiies elongatus (Swainson, 1823), a rare species restricted to the Amazon and Parana Basins, is described by first time, showing a group of conchological and anatomical characters exclusive of this species that may be analyzed to identify it. Diagnosis of A. elongatus: shell long antero-posteriorly, umbones prominent, periostracum opaque and smooth, two posterior radial striae; middle fold of mantle edge veiy tall; gill long antero-posteriorly and short dorso-ventrally, extending about a half of it total length beyond visceral mass; palps proportionally small, several furrows in its outer surface; stomach without esophageal transversal ridjp, dorsal hood and gastric shield poorly developed, major typhlosole entering in ddd , posterior pouch of sa³ very-long; style sac reduced, without crystalline style; distal region of intestine and rectum with a well developed typhlosole, "T" in section, other intestinal regions without folds; gonad gonochoristic.

Here is an anatomical concept of Anodontites trapesialis (Lamarck, 1819) (Bivalvia, Unionoida, Mycetopodidae) from South America. This complementary anatomical study, with a systematic interest, refers to a group of anatomical data, exclusive for this species, that may be analized to identify this wide‐ranging South‐American species, with such a variable shell. Diagnosis of A. trapesialis: trapezoid large shell, thin wall, smooth periostracus. Mantle border without tentacles, even in incurrent and excurrent canals. Presence of a fourth mantle fold well developed. Palps smooth outward, internally with relativelly large, easily view folds, and a smooth margin. Gills with transversal wide folds. Thin walled anal papilla. Evidence in some specimens of palliai cardinal muscle. Hermaphroditic gonad.

It is described the histopathology of the infection of Tilapia rendalli (Osteichthyes, Perciformes, Cichlidae) and Hypostomus regani (Osteichthyes, Siluriformes, Loricariidae) by lasidium larvae of Anodontites trapesialis (Mollusca, Bivalvia, Mycetopodidae). The larvae were encysted within the epidermis of the host, being surrounded by a thin hyaline membrane, 3-6 microm thick, of parasite origin. A proliferative host cell reaction did not occur. The histopathology of the infection shows that the lesions induced by the parasites are minimal. However, the numerous small lesions produced by the release of the larvae may provide optimal conditions for the infection by opportunistic pathogens, namely fungus, which may eventually cause the death of the host.

The aim of this work was to register the occurrence of Anodontites tenebricosus (Bivalvia: Mycetopodidae) in the Sapucaí river basin, municipality of São Joaquim da Barra, São Paulo state, Brazil, associating its occurrence to the environment in which they are found, besides providing conchological data to contribute to the identification of the species. Fifty one specimens of Anodontites tenebricosus were studied regarding their conchological and morphometrical aspects. Strong correlations were found between the morphometric variables, the correlation between 'length and height of the shell' being the most significant. The characteristics of the shells of A. tenebricosus found in the Sapucaí river basin resemble the descriptions of the species found in the literature; therefore, we are able to expand the area of occurrence of the species for the state of São Paulo. Os objetivos deste trabalho foram registrar a ocorrência de Anodontites tenebricosus (Bivalvia: Mycetopodidae) na bacia do rio Sapucaí, no município de São Joaquim da Barra, estado de São Paulo, Brasil, associando sua ocorrência ao ambiente em que são encontrados, além de fornecer dados conquiliológicos que contribuem para a identificação da espécie. Cinquenta e um espécimes de Anodontites tenebricosus foram estudados sob aspectos conquiliológicos e morfométricos. Foram encontradas fortes correlações entre as variáveis, sendo a correlação entre "comprimento e altura da concha" a mais significativa. As características das conchas de A. tenebricosus encontradas na bacia do rio Sapucaí assemelham-se às descrições da espécie na literatura; podemos, assim, ampliar a área de ocorrência da espécie para o estado de São Paulo.

The phases of embryonic development of Anodontites trapesialis lasidia are described for the first time. Adult specimens were obtained from two fish farms located in Londrina, Paraná, Brazil. The internal demibranchs of 120 individuals were studied using a routine histological technique; 70 of these carried eggs and/or larvae in the marsupium and were utilized for the description of the phases of embryonic development. The demibranchs of five specimens were evaluated by scanning electron microscopy to detail the morphology of the larvae. Five phases of development were established: phase I, corresponding to the initial stage of cleavage with the formation of apical cells; phase II, including the stages of the morula and blastula; phase III, where the gastrula forms; phase IV, where the larva formed is still inside the egg envelope; and phase V, where the lasidium can still be identified immediately after eclosion. As fases do desenvolvimento embrionário das lasídias de Anodontites trapesialis são descritas pela primeira vez. Espécimes adultos foram obtidos de duas pisciculturas localizadas no município de Londrina, Paraná, Brasil. As demibrânquias internas de 120 indivíduos foram estudadas por técnicas histológicas rotineiras; 70 apresentavam ovos e/ou larvas no marsúpio e foram utilizadas para a descrição das fases do desenvolvimento embrionário. As demibrânquias de cinco espécimes foram avaliadas por microscopia eletrônica de varredura para detalhar a morfologia da larva. Cinco fases do desenvolvimento foram estabelecidas: fase I, correspondente ao estágio inicial da clivagem com formação das células apicais; fase II, incluindo os estágios de mórula e blástula; fase III, na qual se forma a gástrula; fase IV, na qual a larva formada ainda encontra-se dentro do ovo; e fase V, na qual a lasidium pode ser identificada imediatamente após a eclosão.

Recently, in Brazil, it has appeared a new and unusual “plague” in lazer and commercial fishing. It is caused by the parasitic larval phase of certain native bivalve mollusks of fresh water known as “Naiades” and its involves the presence of big bivalve of fresh water, mainly Anodontites trapesialis, in the tanks and dams of the fish creation. These bivalve mollusks belong to the Unionoida Order, Mycetopodidae Family. The objective of the present work was to analyze the shells of these mollusks to verify the possibility of use as bioindicators for heavy metals in freshwater. The mollusks shells were collected in a commercial fishing at Londrina‐PR. A qualitative analysis was made to determine the chemical composition of the shells and verify a possible correlation with existent heavy metals in the aquatic environment. In the inner part of the shells were identified the elements Ca, P, Fe, Mn and Sr and in the outer part were identified Ca, P, Fe, Mn, Sr and Cu. The Ca ratio of the outer part by inner part of the analyzed shells is around of 1, as expected, because Ca is the main compound of mollusks shells. The ratio of P, Fe, Mn, and Sr to the Ca were constant in all analyzed shells, being close to 0.015. The ratio Cu/Ca varied among the shells, showing that this mollusk is sensitive to concentration of this element in the aquatic environment.

Starting from freshwater mussels sampled mainly during low water seasons of 2004 and 2007, on the lower Aripunã River, a tributary from Madeira River, from the Amazon Basin, a pictorial key for the species identification is presented. Eleven taxa, ten to species level, were identified.

Based on optical and SEM microscopic observations, the projections of the outer surface of the periostracum and inner micro-structures of the shell are described and redefined. The outer surface of the periostracum is practically smooth in both species. Considering a mesoscopic view of the periostracum, A. trapesialis (Lamarck, 1819) presents regular corrugations in the form of radial sequences of arches on the disk region, isolated rays or horizontal sequences of rays on the anterior lower region. A. elongatus presents corrugations formed by series of oblique arches on the disc and oblique rays on the carina. Under SEM, micro ridges were more evident in A. elongatus, but a wide diversity of shapes and patterns of micro fringes were observed in A. trapesialis, especially in young individuals. Considering the profile of the shell layers, the periostracum is relatively thin and apparently simple in A. trapesialis and thinner in A. elongatus. The prismatic layer is thick in both species, consisting of a single series of elongated prisms and wedge-shaped prisms close to the outer surface. The nacreous layer consists of very fine lamellae without pattern or with a slight staircase-like; in A. elongatus this layer is divided by a laminar inclusion of conchiolin. The fringes are abundant and diversified in A. trapesialis, a species less resistant to desiccation due to the presence of a wide intervalvar gap. The existence of a greater density of micro fringes and spikes in juveniles may be related to the orientation of the animal in order to search for an ideal site for development or for escape from regions subject to seasonal droughts, like Pantanal. Projeções da superfície externa do perióstraco e micro estruturas da concha foram redefinidas com base na microscopia óptica e eletrônica de varredura. A superfície do perióstraco é praticamente lisa em ambas espécies. Sob vista mesoscópica, A. trapesialis (Lamarck, 1819) apresenta corrugações regulares formando seqüências radiais de arcos na região do disco, raios isolados ou seqüências horizontais na região antero inferior. A. elongatus (Swainson, 1823) apresenta séries de arcos organizados radialmente no disco e arcos oblíquos na carena. Sob MEV, as micro estrias são mais evidentes em A. elongatus; A. trapesialis apresenta micro franjas muito diversas quanto a forma e padrão, principalmente em jovens. Considerando as camadas da concha, o perióstraco é mais fino em A. elongatus. A camada prismatica é espessa nas duas espécies, com uma série única de prismas alongados e em forma de cunha próximo à superfície externa. A camada nacarada compõe-se de lamelas muito finas, sem padrão ou do tipo escadaria; em A. elongatus esta camada é dividida por uma inclusão laminar de conchiolina. As franjas são abundantes e diversificadas em A. trapesialis, espécie menos resistente à dessecação devido à presença de ampla fresta intervalvar. A ocorrência de uma grande densidade de micro franjas e espinhos nos juvenis, estaria relacionada à orientação do animal na busca por local ideal ao seu desenvolvimento ou para escapar das regiões sujeitas às secas sazonais, como o Pantanal.

Studies were carried out to investigate the contamination of Piracicaba and Mogi-Guaçu River basins (São Paulo State, Southeastern, Brazil) for heavy metals (Cd and Pb), using the limnic bivalve Anodontites trapesialis as a biological monitor. The results showed that the concentrations of Pb were higher than the control group in both basins, showing the bioavailability of this non-essential element in the basins. The concentrations were higher in the Mogi-Guaçu than in the Piracicaba basin, and in the slightly contaminated sites in both basins. There was no correlation between the degree of human impact and Cd and Pb concentrations, it was not possible to infer about concentrations of these heavy metals in the bivalves based only in a broad evaluation of human impact.O principal objetivo deste estudo foi investigar a contaminação pelos metais pesados Cd e Pb nas bacias dos rios Piracicaba e Mogi-Guaçu (Estado de São Paulo, Brasil), utilizando o bivalve limnico Anodontites trapesialis como indicador biológico. As bacias estudadas apresentam diferentes graus de impacto, sendo a qualidade da água geralmente melhor na bacia do rio Mogi-Guaçu. Os teores de Pb detectados nos bivalves não podem ser considerados críticos, contudo, houve acúmulo em relação ao grupo de controle em ambas as bacias, especialmente na bacia do rio Mogi-Guaçu. As maiores concentrações dos elementos, especialmente Pb, foram observadas nos locais menos poluídos e na bacia menos degradada. Este fato sugere que estas concentrações não estão sendo afetadas apenas pelas atividades antrópicas nas bacias, mas deve-se considerar também fatores que afetem a biodisponibilidade ou fontes específicas e não pontuais.

This chapter will be a short introduction for a non-specialist to the order Unionoida (= naiads). These large mussels live exclusively in freshwaters all over the earth (Chaps. 2, 10, 15, this Vol.). A problem for the people dealing with this group is its systematic classification (Chaps. 3, 4, 14, this Vol.). This problem is due to the low number of adult characters which may be used for systematics (Chaps. 4, 14, 15, this Vol.). Though there are some 1000 species, naiads have radiated very little in basic structure. Furthermore, a high degree of plasticity (Chaps. 5, 7, this Vol.) renders characters like shell morphology or size unreliable for classification. New biochemical methods (e.g. immunoelectrophoretic or DNA sequence analyses) may be a way out of this dilemma, and most contributions in this book (e.g. Chaps. 5, 13, 15, this Vol.) therefore follow the classification proposed in Chapter 14 (this Vol.). The order Unionoida comprises two superfamilies: Etherioidea (with the families Mycetopodidae and Iridinidae) and Unionoidea (with the families Hyriidae, Unionidae and Margaritiferidae). Very little is known about the Etherioidea, which are confined to the tropics of America and Africa (Chap. 6, this Vol.). However, the data so far suggest that their life history is quite similar to that of the Unionoidea.

The zoogeographic links between the freshwater fauna (sponges, molluscs and fishes) of the mid Parana river and the Uruguay river have been noticed by different authors (Ihering 1919; Bonetto 1961; Parodiz 1963; Bonetto and Ezcurra 1966; Bonetto 1967; Bonetto et al. 1983; Lopez et al. 2008). Three species of freshwater mussels of the family Mycetopodidae, Mycetopoda soleniformis (d'Orbigny, 1835), Lamproscapha ensiformis (Spix, 1827) and Anodontites trigonus (Spix, 1827) have been registered for the first time in the mid Uruguay river in the last years (Olazarri 1979; 1985; Mansur et al. 2003). These typically Amazonian species would be undertaking a process of austral propagation (Bonetto et al. 1983).

The unionid Anodontites trapesilais (Lamarck, 1819) like most freshwater mussels is a parasite of fish. So it is trivial to assume that the availability of hosts is an important factor for the maintenance of unionoid populations. What seems obvious is not always so easy to demonstrate. This study proposes to investigate the effects of abiotic and biotic variables related to the incubation of larvae in A. trapesialis. For this, we estimate different biological indexes and try to capture the dimensionality of the fish, along with the temporal variation of environmental variables. From the application of a CCA, it was demonstrated that there was a synchronicity among the factors and variables proposed here, and we infer that the flood pulse acts as a synergistic factor in this process.

A anatomia funcional comparada de duas espécies de bivalves límnicos, é analisada. Anodontites trapezeus e Anodontites trapesialis, pertencem à família Mycetopodidae e são comuns no interior do Estado de São Paulo. Vivem no mesmo local e são adaptadas ao ambiente de águas calmas. Foram, pela primeira vez, estudadas sob o ponto de vista da anatomia funcional e, o estudo do estômago contribuiu com valiosas informações, mostrando que, de maneira geral, a estrutura interna é de grande uniformidade nesses animais, tal como ocorre entre os Unionacea, estudados por outros autores.