Phylogenetic position inferred on SSU rDNA sequence gene and description of a new parasitic cnidarian (Endocnidozoa: Myxobolidae) infecting Markiana nigripinnis (Teleostei: Stevardiinae) from a small marginal lake floodplain, Brazil.

Herein, a detailed molecular phylogeny analysis was developed to determine the phylogenetic position of a new freshwater histozoic myxosporean cnidarian, Henneguya markiana sp. nov. from the world's largest tropical wetland area, Pantanal, Brazil. The new species is described using an integrative taxonomy approach including morphology, biological traits and molecular data. Phylogenetic analysis inferred by Maximum Likehood method showed the new Henneguya species in a well-supported clade of myxosporean gill parasites of South American characids fishes. In this same clade, the new Henneguya described appeared in a sub-clade clustering with H. lacustris and H. chydadea. Nevertheless, the sequences of the new species and H. lacustris and H. chydadea have a large genetic divergence of 10.4% (148 nucleotides-nt) and 10.5% (147 nt) respectively. To the best of our knowledge, this is the first report of a cnidarian myxosporean species parasitizing a fish from Stevardiinae from South America. In the light of the differences observed from the integrative taxonomy, we are confident that this isolate is a new species of Henneguya, increasing the knowledge of diversity of this enigmatic group of cnidarians.

Ultrastructure, surface topography, morphology and histological observations of a new parasitic cnidarian of the marbled swamp eel from the world's largest tropical wetland area, Pantanal, Brazil.

Myxosporeans are a diverse group of microscopic cnidarians of wide distribution that evolved into a parasitic lifestyle. A new myxosporean species, Myxobolus sp., is herein described infecting the mandible of wild specimens of Synbranchus marmoratus, caught in the world's largest tropical wetland area, Pantanal, Brazil. Light, scanning, transmission electron microscopy and histological observations unveiled detailed taxonomic information of the new myxosporean cnidarian. Ultrastructural analysis revealed a detailed description of plasmodia structures which can be used for comparison with plasmodia from other species of myxobolids. Both histological and ultrastructural observations evidenced a connective tissue capsule surrounding the plasmodia of Myxobolus sp. as a histopathological host reaction to the infection of this parasitic cnidarian. Histology showed that tissue tropism of the new myxosporean occurs in a well-defined part of the mandible, with development of plasmodia occurring in the epidermis layer. Mature myxospores from the valvular view featured an ovoid shape and had a short prolongation of the spore valves in the posterior end. Myxospores measured 22.7 ± 1.2 µm (21.5-23.9 µm) in length, 12.5 ± 0.4 µm (12.1-12.9 µm) in width and 11.3 ± 0.5 (10.8-11.8 µm) in thickness. Polar capsules were pyriform equally-sized and measuring 4.6 ± 0.3 µm (3.9-4.3 µm) in length and 2.9 ± 0.1 µm in width (2.8-3.0 µm). Finally, this study substantiates the still hidden myxosporean diversity from South America.

New arrangement of three genera of fish tapeworms (Cestoda: Proteocephalidae) in catfishes (Siluriformes) from the Neotropical Region: taxonomic implications of molecular phylogenetic analyses.

Tapeworms (Cestoda: Proteocephalidae) are the dominant component of communities of intestinal parasites in pimelodid and other catfishes (Siluriformes) from South America. Even though these parasites have been studied intensively over more than one century, molecular taxonomy and phylogenetics have questioned their morphology-based classification, thus raising doubts about the systematic value of traits commonly used to circumscribe individual taxa. In the present study, members of three morphologically well-characterized genera of proteocephalids from pimelodid (Hemisorubim platyrhynchos and Sorubim lima) and auchenipterid (Ageneiosus inermis) catfishes from the Paraná or Amazon River basins were subjected to DNA sequencing of the large subunit nuclear ribosomal RNA (lsrDNA) and complete mitochondrial cytochrome c oxidase subunit I (COI). Phylogenetic analyses revealed the sister relationship between Manaosia bracodemoca and Mariauxiella piscatorum, and among Mariauxiella pimelodi and Ageneiella brevifilis. As a result, Mar. piscatorum and A. brevifilis are transferred to Manaosia and Mariauxiella, respectively, as Manaosia piscatorum n. comb. and Mariauxiella brevifilis n. comb., and the genus Ageneiella is suppressed. Diagnoses of Manaosia and Mariauxiella are amended. In addition, the present study revealed misidentification of tapeworms whose sequences are deposited in the GenBank database.

An integrative approach assesses the intraspecific variations of Procamallanus (Spirocamallanus) inopinatus, a common parasite in Neotropical freshwater fishes, and the phylogenetic patterns of Camallanidae.

Integrative taxonomy was used to evaluate two component populations of Procamallanus (Spirocamallanus) inopinatus in Brazil and the phylogeny Camallanidae. Parasite populations were collected in the characiform Anostomoides passionis from River Xingu (Amazon basin) and Megaleporinus elongatus from River Miranda (Paraguay basin). Morphology was analysed using light and scanning electron microscopy (SEM). Genetic characterization was based on partial sequences of the 18S and 28S rDNA, and COI mtDNA. Phylogenies were based on 18S and COI due to data availability. Generalized Mixed Yule Coalescent (GMYC), Poisson Tree Process (PTP) and *BEAST were used for species delimitation and validation. SEM revealed for the first time the presence of minute denticles and pore-like structures surrounding the oral opening, phasmids in females and confirmed other important morphological aspects. Statistical comparison between the two-component populations indicated morphometric variations, especially among males. The different component population of P. (S.) inopinatus showed variable morphometry, but uniform morphology and were validated as conspecific by the GMYC, PTP and *BEAST. Some camallanid sequences in GenBank have incorrect taxonomic labelling. Host, environment and geographic aspects seem to be related to some lineages within Camallanidae; however, their real phylogenetic meanings are still unclear.

Three new species of Anacanthorus Mizelle & Price, 1965 (Monogenea: Dactylogyridae) from Markiana nigripinnis Perugia (Actinopterygii: Characidae) in Pantanal wetlands, Brazil.

Three monogenean species, Anacanthorus luquei n. sp., A. scholzi n. sp. and A. cohenae n. sp. are described from the gills of the tetra fish Markiana nigripinnis (Perugia) (Characidae), collected in the Pantanal wetlands, State of Mato Grosso do Sul, Brazil. Among other differences, Anacanthorus luquei n. sp. differs from the most morphologically similar species, based on the structure of the accessory piece as follows: branches with smooth margins (vs with irregular margins in A. cuticulovaginus), without pointed projections at distal end (vs with projections in A. dipelecinus) and with 2 branches (vs 3 in A. quinqueramus). Anacanthorus scholzi n. sp. is most morphologically similar to A. luquei n. sp., differing from it because one of the branches of the accessory piece is bifurcated at the distal portion. Anacanthorus cohenae n. sp. can be differentiated from the congeners based on the combination of the following features: MCO cylindrical and robust with sclerotised flanges on the extremities, accessory piece V-shaped, bearing two branches similar in length and with blunt distal ends, and hooks with a proximal bulb. This is the first parasitological study on M. nigripinnis and, currently, Anacanthorus allocates 88 species infesting characiform fishes in the Neotropical region, including the three new species described here.

Integrative taxonomy of Sprentascaris mahnerti and phylogeny of raphidascaridid nematodes (Nematoda: Ascaridoidea: Raphidascarididae) suggest the monophyly of Sprentascaris.

Sprentascaris mahnerti (Nematoda: Raphidascarididae) collected from Loricariichthys labialis (Siluriformes: Loricariidae) in the Pantanal wetlands, State of Mato Grosso do Sul (Brazil), was redescribed using light and scanning electron microscopy (SEM), and genetically characterised along with two other raphidascaridids: Raphidascaroides brasiliensis and Ro. moraveci. Due to the systematic discussion regarding Raphidascaris and Sprentascaris, as well as the poor knowledge about the phylogenetic relationships within Raphidascarididae, phylogenies were reconstructed based on partial sequences of the 18S and 28S nuclear rRNA gene, the nuclear ITS1-5.8S-ITS2 and the cytochrome c oxidase subunit I (cox1) mtDNA. Morphological study of S. mahnerti, confirmed some previously described features, revealed new characteristics and permitted to elucidate some inconsistencies noted in the literature. Morphological and genetic characterisation of S. mahnerti supported its validity. Phylogenetic reconstructions supported the monophyly of Sprentascaris, which has three pairs of interlabial conspicuous cuticular projections as a synapomorphy. The relationships among several lineages of raphidascaridids were unsolved, albeit Goezia and Ichthyascaris formed well-supported monophyletic assemblages, in which the first included species with no relations regarding the habitat of hosts and the geographic origin. The present findings represent one more step towards the understanding of the interrelationships of raphidascaridid nematodes. In this sense, Sprentascaris should be considered valid as an independent lineage from Raphidascaris.

An integrative taxonomic assessment of Procamallanus (Spirocamallanus) huacraensis (Nematoda: Camallanidae), infecting the freshwater catfish Trichomycterus spegazzinii (Siluriformes: Trichomycteridae) in Argentina.

Procamallanus (Spirocamallanus) huacraensis infecting the catfish Trichomycterus spegazzinii from Escoipe River, Salta province (Argentina), is redescribed and genetically characterised for the first time, based on three genetic markers (nuclear 18S and 28S rRNA; cytochrome c oxidase subunit I [cox1] mtDNA). The phylogeny of Camallanidae was also discussed. Morphological evaluation of P. (S.) huacraensis using light and scanning electron microscopy revealed the previously undescribed features: location of deirids, accurate morphology of larvae (L1) and ovijector in females, as well as phasmids in males. Differences were found comparing the newly collected material and the type specimens, probably because the original description lacked detailing. Unfortunately, type specimens of P. (S.) huacraensis were no available for loan. The results of morphological and genetic analyses supported the validity of P. (S.) huacraensis. Inconsistencies regarding the taxonomic identification of species of Camallanidae in GenBank database were noted. Based on the current genetic database of Camallanidae, phylogenetic reconstructions using the 18S rRNA sequences were most consistent, due to the inclusion of higher number of taxa. Procamallanus (S.) huacraensis appeared as sister group of P. (S.) rarus, also isolated from a catfish in a neighbouring region. The order and habitat of hosts were also similar within some well-supported parasite lineages, but without common geographic origin. However, it is still premature to make definitive affirmations regarding the role of such features in the phylogenetic patterns of Camallanidae, given the scarcity of genetic data. The phylogenetic reconstructions also confirmed the artificiality of the morphology-based systematics of the family.

Occurrence of Isopods in Two Species of Snappers (Lutjanidae) from Northeast Brazil.

Parasitic isopod species are poorly known in the northeastern coast of Brazil. In this sense, this study presents novel records of Isopoda of the families Aegidae, Cymothoidae, and Corallanidae. A total 69 specimens of Lutjanus analis and 19 of Lutjanus jocu, of which 46 isopods from 3 different species were collected, i.e. Rocinela signata, Cymothoa excisa, and Excorallana richardsoni. The species R. siganata and E. richardsoni are reported for the first time in L. jocu. A significant relationship between the parasite R. signata and the size of the fish L. jocu was also observed. The isopod C. excisa is considered an incidental finding in L. analis. To the authors' knowledge, this is the first report of this species in fish from Brazil. The three species of isopods are new occurrences in the State of Sergipe, northeast region of the country. An additional morphological characteristic observed in the dorsal setae of pleotelson in specimens of E. richardsoni was that one end of this structure wws bifid. This information contributes to the current body of knowledge of the morphology of this particular species.

First description of the male of Philometroides acreanensis and phylogenetic assessment of Philometridae (Nematoda: Dracunculoidea) suggest instability of some taxa.

The male of Philometroides acreanensis, parasitic in the anterior intestine external wall of the freshwater catfish Pimelodus blochii, from the Brazilian Amazon, is described for the first time. Additional data on the morphology of females is given. The new morphological data strengthened the validity of the species as well as its first genetic characterization, using three nuclear genetic markers (18S and 28S of the rDNA and ITS1-58S-ITS2), confirmed the high genetic resemblance of male and female specimens. Philometroides acreanensis shows morphological features of the generic diagnosis of Neophilometroides, Alinema, Philometra and Philometroides. Phylogenetic analyses using sequences of the18S rDNA from representatives of Dracunculoidea confirmed the validity of P. acreanensis and its close relatedness with Alinema rather than with other genera. The validity of Philonemidae was confirmed, as was the monophyly of Philometridae and Clavinema. However, Dentiphilometra, Philometra and Philometroides appear not to be monophyletic. Host taxa, habitat and geographic occurrence seem to have some relationship with the evolutionary traits of certain phylogenetic assemblages of philometrids, which were highly supported in the phylogentic reconstructions. Even though interesting aspects of the phylogeny and taxonomy of Philometridae came to light, further integrative approaches should be used that include additional genetic markers, due to the loose boundaries between some genera as observed here.

Community structure of metazoan parasites from Pimelodus blochii in two rivers of the Western Brazilian Amazon: same seasonal traits, but different anthropogenic impacts.

The present investigation evaluated the influence of seasonality and locality on the structure of the parasite community of the catfish Pimelodus blochii. A total of 160 fish were collected from two rivers in the State of Acre, western Brazilian Amazon: 80 fish in River Acre and 80 in River Iaco, with 40 in each season (rainy and drought). The overall prevalence was 78.7% and 1461 parasite specimens (adults and larvae) were allocated in 22 taxa: 5 of Monogenea, 10 of Nematoda, 3 of Digenea, 1 of Cestoda and 3 of Crustacea. In drought season, Procamallanus (Spirocamallanus) pimelodus and Demidospermus peruvianus were more prevalent in River Acre and Iaco, respectively. The parasite diversity (Brillouin index) as well as the prevalence and abundance of the monogeneans D. peruvianus, D. striatus, Demidospermus sp. and Ameloblastella sp. were higher in River Acre. The parasite community structure were dissimilar among rivers, and seasonally in River Iaco. These results suggest that environmental traits may overshadow seasonal influences on the parasite community structure, which may be related to the higher anthropization in River Acre. Furthermore, seasonality exerted less influence on the parasite community than expected, probably because the two rivers have different hydrological traits than those of other rivers in the Brazilian Amazon. New host and locality records expanded our knowledge of parasite biodiversity of P. blochii.

Molecular phylogeny of the gill parasite Henneguya (Myxosporea: Myxobolidae) infecting Astyanax lacustris (Teleostei: Characidae) from fish farm in Brazil.

Molecular data of Henneguya chydadea Barassa, Cordeiro and Arana, 2003, found in the gill filaments of Astyanax lacustris bred in fish farm in the State of Mato Grosso do Sul, Brazil was obtained in order to estimate their phylogenetic position among other platysporines myxosporean. The prevalence of the parasite was 28.1% and the range intensity was 1-3 plasmodia per fish. The shape and measurements of mature myxospores were consistent with the characteristics previously defined to H. chydadea. The SSU rDNA sequence of the myxospores of H. chydadea resulted in a total of 1405 nucleotides, and this sequence did not match any of the myxozoan available in the GenBank. Phylogenetic analysis showed H. chydadea within the clade of histozoic myxosporeans and closed together with Henneguya rotunda and Myxobolus pantanalis reported in the gill arch and fins and gill filaments of Salminus brasiliensis respectively. Nonetheless, the SSU rDNA sequences of H. chydadea, H. rotunda and M. pantanalis have only 85.2% and 84.4% similarity, respectively. This is the first molecular study of a Henneguya species that parasitizes a fish belonging to the genus Astyanax in South America. The importance of myxosporeans introduction to new locations along with infected cultured host is emphasized.

Redescription of the nematode parasites of lizards: Strongyluris oscari Travassos, 1923 (Heterakidae) from Brazil and Pharyngodon mamillatus (Linstow, 1897) (Pharyngodonidae) from Egypt.

Strongyluris oscari Travassos, 1923, parasite of Topidurus torquatus (Wied-Neuwied, 1820) (Tropiduridae) from Brazil and Pharyngodon mamillatus (Linstow, 1897) of Chalcides ocellatus (Forskal, 1775) (Scincidae) from Egypt, were redescribed based on light and scanning electron microscopy, and re-evaluation of specimens from parasitological collections. The following features were accurately observed in S. oscari for the first time: structure of lips and pharyngeal valve, presence and distribution of somatic papillae, number and arrangement of caudal papillae, presence of inner sclerotised structures supporting the ventral sucker and the ventral region in tail of males, and structure of the posterior anal lip in females. The unpaired papilla on the inferior edge of the ventral sucker in males of S. oscari is a cuticular groove instead of a true papilla. Regarding the morphology of P. mamillatus the following features were given in details for the first time: structure of the cephalic end in both male and female, location of amphids, position of phasmids in females and the accurate morphology of caudal bursa in males, including the distribution of caudal papillae and the genital cone morphology. Strongyluris oscari and P. mamillatus have no intraspecific morphological variations, but wide range on biometric features. These variations may be accounted by host/environment attributes, since they exhibit wide host and geographical spectra. The present results increased the morphological knowledge of P. mamillatus and S. oscari, strengthening their taxonomic validity.

Parapharyngodon hugoi n. sp., a new nematode (Oxyuroidea: Pharyngodonidae) of the tree frog Trachycephalus typhonius (Linnaeus) from the Brazilian Pantanal, including a key to the congeners from amphibians of the American continent.

A new nematode Parapharyngodon hugoi n. sp. (Oxyuroidea: Pharyngodonidae) is described parasitising the large intestine of the tree frog Trachycephalus typhonius (Linnaeus) (Anura: Hylidae) from the wetlands of Pantanal, State of Mato Grosso do Sul, Brazil. The new species exhibits a unique structure of the posterior cloacal lip in males, which is supported by a rigid V-shaped structure. Parapharyngodon hylidae parasitic in hylid frogs, including T. typhonius, from Mexico, is the most similar congener to P. hugoi n. sp. but is distinguished from the new species by the presence of a gubernaculum (vs absence), by the lateral alae in males ending far anterior to cloacal opening (vs near to it) and because in gravid females the ovaries encircle the oesophageal corpus. Additionally, the new species differs from its congeners as well as from species of Thelandros Wedl, 1862, a very closely related genus, by the combination of features such as spicule length, number of caudal papillae, morphology of the anterior cloacal lip, which is echinate, and position of ovaries. The geographical distribution of hosts seems to play an important role in the speciation process of Parapharyngodon spp.; however, due the lack of molecular data this issue along with the validity of both Thelandros and Parapharyngodon are still questions to be solved in the future, after improvement of the genetic database. A key to the species of Parapharyngodon parasitic in amphibians from the American continent is provided.

A morphological and molecular study of two species of Raphidascaroides Yamaguti, 1941 (Nematoda: Anisakidae), parasites of doradid catfish (Siluriformes) in South America, with a description of R. moraveci n. sp.

Nematodes of the genus Raphidascaroides Yamaguti, 1941 parasitising doradid catfishes (Siluriformes: Doradidae) in Brazil were studied based on morphological and molecular evaluation of newly collected material. A new species, Raphidascaroides moraveci n. sp., is described from the intestine of Platydoras armatulus (Valenciennes) from River Miranda, River Paraguay basin, Pantanal, Mato Grosso do Sul. The new species differs from all of the congeners in having short spicules (163-217 µm in length) representing less than 1% of the total body length and in the posterior region of cloacal opening covered by small rudimentary spines. In addition, it differs from the other congeneric species in the number and arrangement of the caudal papillae and the structure of lips and tail. Raphidascaroides moraveci n. sp. is the third species described from freshwater fishes and the second one in the Neotropical Region. New morphological data on R. brasiliensis Moravec & Thatcher, 1997 from Megalodoras uranoscopus (Eigenmann & Eigenmann) and Platydoras costatus (Linnaeus) (both new host records) from River Xingu, River Amazon basin, Pará, are provided including scanning electron micrographs of taxonomically important structures. The differentiation of the new species is supported by molecular data (partial sequences of the small and large subunits of the rRNA gene).

A Morphological and Molecular Study of Spectatus spectatus (Kathlaniidae), Including Redescription of the Species and Amendment of Genus Diagnosis.

Spectatus spectatus Travassos, 1923 (Nematoda: Kathlaniidae) found in the intestine of Piaractus mesopotamicus (Holmberg, 1887) (Characiformes: Serrasalmidae) from the River Miranda, Mato Grosso do Sul, Brazil is redescribed based on morphological evaluation of newly collected material and examination of type and voucher specimens from the Coleção Helmintológica do Instituto Oswaldo Cruz. The following characteristics previously unreported or insufficiently described were observed: morphology of lips, presence of lamellae-like supplementary lips, presence of pharynx and cuticular ring surrounding the oral opening associated with a complex cuticular apparatus anterior to the pharynx, the number and arrangement of caudal papillae (13 pairs plus 1 unpaired), and the position of nerve ring. Since S. spectatus is the type species of Spectatus, the diagnosis of this Neotropical genus is amended. Synonymy of Chabaudinema Díaz-Ungría, 1968 with Spectatus, first proposed in 1980 by Baker, is supported by the present data. Molecular data that include the first sequence of the SSU rDNA for any species of Spectatus indicate a basal position of S. spectatus within Cosmocercoidea, forming a distant lineage from that comprising 2 species of Falcaustra Lane, 1915. This separate position of S. spectatus supports validity of the genus.

Diet and nematode infection in Proceratoprhys boiei from two Atlantic rainforest remnants in Southeastern Brazil.

Proceratophrys boiei is an endemic cycloramphid anuran inhabiting the leaf litter of Atlantic rainforests in Southeastern Brazil. We analyzed the whole digestive tract of 38 individuals of Proceratophrys boiei collected in two Atlantic Rainforest areas in the state of Rio de Janeiro, Brazil, to study the diet composition and the helminth fauna associated with this species. The main food items in P. boiei's diet were Coleoptera, Orthoptera and Blattaria. Five nematode species were found: Aplectana delirae, Cosmocerca parva, Oxyascaris oxyascaris, Physaloptera sp. (larval stage only) and an unidentified nematode. Overall prevalence was 71% and mean infection intensity was 7.3 ± 5.8 neatodes per individual.

Diet and nematode infection in Proceratoprhys boiei (Anura: Cycloramphidae) from two Atlantic rainforest remnants in Southeastern Brazil

Proceratophrys boiei is an endemic cycloramphid anuran inhabiting the leaf litter of Atlantic rainforests in Southeastern Brazil. We analyzed the whole digestive tract of 38 individuals of Proceratophrys boiei collected in two Atlantic Rainforest areas in the state of Rio de Janeiro, Brazil, to study the diet composition and the helminth fauna associated with this species. The main food items in P. boiei's diet were Coleoptera, Orthoptera and Blattaria. Five nematode species were found: Aplectana delirae, Cosmocerca parva, Oxyascaris oxyascaris, Physaloptera sp. (larval stage only) and an unidentified nematode. Overall prevalence was 71 percent and mean infection intensity was 7.3 ± 5.8 neatodes per individual.

Proceratophrys boiei é um anuro da familia Cycloramphidae que vive no folhico e é endêmico de areas de floresta na Mata Atlantica do Sudeste do Brasil. Nós analisamos o trato digestivo de 38 indivíduos de Proceratophrys boiei provenientes de duas áreas de Mata Atlântica no Estado do Rio de Janeiro, Brasil, para estudar a composição da dieta e a fauna helmíntica associada a esta espécie. s principais itens alientares na dieta de P. boiei fora Coleoptera, rthoptera e Blattaria. Cinco espécies de nematóides foram encontradas: Aplectana delirae, Cosmocerca parva, Oxyascaris oxyascaris, Physaloptera sp. (apenas larvas) e uma espécie de nematóide não identificada. A prevalência total foi de 71 por cento e a intensidade media de infecção foi de 7,3 ± 5,8 nematóides por indivíduo.

[Relationship between biomass and parasite density of Mediorhynchus emberizae (Acanthocephala: Gigantorhynchidae) parasites of Paroaria dominicana (Passeriformes: Emberizidae) of the State of Bahia, Brazil]. / Relação entra biomassa e densidade parasitária de Mediorhynchus emberizae (Acanthocephala: Gigantorhynchidae) parasito de Paroaria dominicana (Passeriformes: Emberizidae) do Estado de Bahia, Brasil.

During the study of the metazoan parasites of Paroaria dominicana (Linnaeus, 1758), eight infrapopulations of Mediorhynchus emberizae (Rudolphi, 1819), were collected in the medium third of the small intestine, with parasite intensities ranging from one to ten specimens. Differences among the average values of the biomass, volume of the eggs, volume of the testicles and the parasite density of the infrapopulations were statistically tested in order to detect variations of these parameters in function of parasite density. Was observed that the acanthocephalans biomass increased with the volume of the intestine and also that the parasite density increased with the parasite intensity in the infrapopulations. It was verified that the increase of the parasite intensity was accompanied by the decrease of the mean biomass of the parasites. Decrease of the volume of the eggs was verified with the increase of the density and of the parasite intensity. The results of the present work could suggested the occurrence of density-dependent factors and the decrease of testicles volume and the biomass of the males with the increase of the parasite density in the infrapopulations of M. emberizae in the intestine of P. dominicana.

Similarity between metazoan parasite communities of two sympatric brackish fish species from Brazil.

Between March 2000 and February 2003, 63 specimens of Genidens barbus and 69 specimens of Aspistor luniscutis (Siluriformes: Ariidae), sympatric species from the coastal zone of Angra dos Reis (23 degrees 01'S, 44 degrees 19'W), RJ, Brazil, were necropsied to study their metazoan parasite communities. Parasite community descriptors were calculated and possible similarities statistically tested. Twenty-two species of metazoan parasites were identified, 15 species from G. barbus and 16 associated with A. luniscutis. Nine species were common to both host species; 4 of them exhibited significant differences in terms of abundance and prevalence. Mean total abundance, species richness, diversity, evenness, and Berger-Parker dominance values were not significantly different in the 2 species of fish. Similarity within parasite infracommunities showed highest homogeneity in A. luniscutis. The parasite infracommunities of A. luniscutis and G. barbus were characterized by ectoparasite dominance and scarcity of species with high prevalence. Nevertheless, low values of similarity were observed between infracommunities, and evidence for 2 distinct infracommunities groups was found.

Relação entre biomassa e densidade parasitária de Mediorhynchus emberizae (acanthocephala: gigantorhynchidae) parasito de paroaria dominicana (passeriformes: emberizidae) do estado da Bahia, Brasil / Relationship between biomass and parasite density of Mediorhynchus emberizae (Acanthocephala: Gigantorhynchidae) parasites of Paroaria dominicana (Passeriformes: Emberizidae) of the State of Bahia, Brazil

Durante o estudo dos metazoários parasitos de Paroaria dominicana (Linnaeus, 1758), oito infrapopulações de Mediorhynchus emberizae (Rudolphi, 1819), foram coletadas no terço médio do intestino delgado, com intensidades parasitárias variando de um a dez espécimes. Diferenças entre os valores médios da biomassa, volume dos ovos, volume dos testículos e da densidade parasitária das diferentes infrapopulações foram estatisticamente testadas com o objetivo de detectar variações desses parâmetros em função da densidade parasitária. Foi observado que a biomassa de acantocéfalos aumentou com o volume do intestino e também que a densidade dos parasitos aumentou com a intensidade parasitária nas infrapopulações. Verificou-se que o aumento da intensidade parasitária foi acompanhada pela diminuição da biomassa média dos parasitos. Constatou-se diminuição do volume dos ovos com o aumento da densidade e da intensidade parasitária. Os resultados do presente trabalho parecem dar indícios da ocorrência de fatores dependentes da densidade e da diminuição do volume testicular e a biomassa dos machos com o aumento da densidade parasitária nas infrapopulações de M. emberizae no intestino de P. dominicana.

During the study of the metazoan parasites of Paroaria dominicana (Linnaeus, 1758), eight infrapopulations of Mediorhynchus emberizae (Rudolphi, 1819), were collected in the medium third of the small intestine, with parasite intensities ranging from one to ten specimens. Differences among the average values of the biomass, volume of the eggs, volume of the testicles and the parasite density of the infrapopulations were statistically tested in order to detect variations of these parameters in function of parasite density. Was observed that the acanthocephalans biomass increased with the volume of the intestine and also that the parasite density increased with the parasite intensity in the infrapopulations. It was verified that the increase of the parasite intensity was accompanied by the decrease of the mean biomass of the parasites. Decrease of the volume of the eggs was verified with the increase of the density and of the parasite intensity. The results of the present work could suggested the occurrence of density-dependent factors and the decrease of testicles volume and the biomass of the males with the increase of the parasite density in the infrapopulations of M. emberizae in the intestine of P dominicana.