Evolutionary morphology of haptoral anchors in monogenoids (Dactylogyridae) of marine catfish (Siluriformes: Ariidae) from the Atlantic coast of South America.

Exploring the phylogenetic signal of morphological traits using geometric morphometry represents a powerful approach to assess the relative weights of convergence and shared evolutionary history in shaping species' forms. We evaluated the phylogenetic signal in shape and size of ventral and dorsal haptoral anchors of 10 species of monogenoids (Hamatopeduncularia, Chauhanellus and Susanlimocotyle) occurring in marine catfish (Siluriformes: Ariidae) from the Atlantic coast of South America. The phylogenetic relationships among these species were mapped onto the morphospaces of shape and size of dorsal and ventral anchors. Two different tests (squared change-parsimony and Kmult) were applied to establish whether the spatial positions in the phylomorphospace were influenced by phylogenetic relationships. A significant phylogenetic signal was found between anchor form and parasite phylogeny. Allometric effects on anchor shape were non-significant. Phylogenetically distant species on the same host differed markedly in anchor morphology, suggesting little influence of host species on anchor form. A significantly higher level of shape variation among ventral anchors was also found, suggesting that the evolutionary forces shaping ventral anchor morphology may operate with differing intensities or exhibit distinct mechanisms compared to their dorsal counterparts. Our results suggest that phylogenetic relationships were a key driver of changes in shape (but not size) of anchors of monogenoids of South American ariids. However, it seems that the emergence of the digitiform haptor in Hamatopenducularia and in some species of Chauhanellus played an important role in the reduction in anchor size and may cause secondary losses of anchors in other groups of monogenoids.

Relationship of the parasite Rhadinorhynchus plagioscionis (Acanthocephala) with Plagioscion squamosissimus host and its specificity of occurrence in the Brazilian Amazon.

Objective was the relationship of the parasite Rhadinorhynchus plagioscionis with its host Plagioscion squamosissimus, providing morphological and morphometric data to prove the specificity of this parasite with its host, with reports occurring only in rivers in the Brazilian Amazon. Rhadinorhynchus plagioscionis infected P. squamosissimus captured in the municipal region of Santarém, in the state of Pará, in the eastern Brazilian Amazon. The specimens were analyzed by light and scanning electron microscopy. Morphological data obtained confirmed conspecificty with R. plagioscionis and supplemental information was added to the morphological concept of this species. The body of R. plagioscionis is cylindrical and milky-coloured with dorsal curvature, a long proboscis displaying ventral curvature with 12 longitudinal rows containing 22 to 24 hooks, which are larger and more prominent towards the end of the ventral curvature, and decrease in size in the posterior extremity of the proboscis. The present study describes, in addition to the morphological and morphometric characteristics of R. plagioscionis, which have host specificity for P. squamosissimus, a relationship being reported exclusively in the Brazilian Amazon.

Morphology and molecular phylogeny of Pauciconfibuloides amazonica gen. n. sp. n. (Platyhelminthes, Monogenoidea) parasitizing the Amazonian croaker Plagioscion squamosissimus.

An integrative study was performed to understand the phylogenetic relationships of an undescribed, freshwater species of microcotylid parasitizing Plagioscion squamosissimus from the Amazon River Basin. Based on morphological and molecular analysis (18S rDNA and partial 28S rDNA genes), a new genus is proposed to accommodate this new species, Pauciconfibuloides amazonica gen. n. sp. n. The new genus is closely related to Protastomicrocotylinae and Pauciconfibula by sharing the vagina, male copulatory organ, and genital atrium all unarmed. However, Pauciconfibuloides gen. n. can be distinguished from those taxa by the prostatic system and position of the vaginal pore. Molecular phylogenetic inference suggests a sister relationship with species of Polylabris (Prostatomicrocotylinae), but to date, there are no available 18S or 28S rDNA sequences of Pauciconfibula to be compared. This is the first report of a microcotylid parasitizing a freshwater sciaenid from South America.

High prevalence and intensity of fish nematodes with zoonotic potential in the Brazilian Amazon, including a brief reflection on the absence of human infections

This study aimed to characterize the prevalence, mean abundance, and mean intensity of potential fish-borne zoonotic nematode larvae infecting the predator fish Hoplias aff. malabaricus from the Tapajós River, in the municipality of Santarém, in the Brazilian Amazon. After capture, the specimens of H. aff. malabaricus were analyzed for infection by Contracaecum sp. and Eustrongylides sp. third-stage larvae, and the prevalence, mean abundance, and mean intensity were calculated. A literature search was carried out to clarify the relationship between these indicators and eventual human cases of infection in the Amazon region. Third-stage larvae of nematodes of the Contracaecum and Eustrongylides genera were found in the specimens of H. aff. malabaricus sampled from the Tapajós River. The prevalence of Contracaecum larvae was 100%, while its mean abundance and mean intensity were both 54.8 larvae/fish. The prevalence of Eustrongylides larvae was 62.9%, and its mean abundance and mean intensity were 1.8 and 2.8 larvae/fish, respectively. Despite the high prevalence and intensity values, there are no cases of human infection by these nematode larvae in the Brazilian Amazon reported. The absence of human infections by these nematode larvae in the Brazilian Amazon despite the high prevalence/intensity of Contracaecum and Eustrongylides larvae and the high consumption of fish in the region, is most probably due to the fact that the local populations do not eat raw or undercooked fish. However, it is noteworthy that the absence of zoonotic cases in the region is based only on the examination of the available published papers. A better knowledge of the situation would require surveying hospitals and clinics, and data from the region's medical treatment facilities. However, the authors consider that cases of human infection, if any, are extremely rare, mainly due to the eating habits of the local population.

Metazoan parasites of Plagioscion squamosissimus (Osteichthyes: Sciaenidae) of two rivers from the eastern Amazon (Brazil).

Plagioscion squamosissimus, commonly known as "white hake" or "corvina", is among the most commercially important fish in the Amazon and host to a great diversity of endoparasites. The aim of the present study was to compare the communities and infracommunities of metazoan parasites that infect P. squamosissimus in two rivers from the eastern Brazilian Amazon. A total of 75 specimens of P. squamosissimus were collected from Lago Grande do Curuái and the mouth of the Tapajós River. Morphological analysis revealed the presence of 16 parasite species, three myxozoans (Myxobolus sp., Ceratomyxa sp., Henneguya sp.), two trematodes (Austrodiplostomum compactum, Digenea gen. sp. (metacercariae), two monogeneans (Diplectanum sp., Euryhaliotrema sp.), three nematodes (Procamallanus (S.) sp., Anisakis sp., Pseudoproleptus sp. (larva), two acanthocephalans (Rhadinorhynchus plagioscionis and Neoechinorhynchus sp.), one Cestoda Ptychobothriidae gen. sp. and three crustaceans (Therodamas sp., Ergasilus sp., Dolops sp.). Six new records of parasites of P. squamosissimus were made, of which three were myxozoan species, one nematode species and two crustacean species. There were differences in the component communities of parasites of both rivers studied and these were discussed.

New records and prevalence of metazoan parasites of fish in the southeastern Brazilian region

Hoplias aff. malabaricus is abundant in the Mogi-Guaçu River. The aim of this study was to perform an inventory of the species of metazoan that parasite this species of fish taken from oxbow lakes of the Mogi-Guaçu River. The Mann-Whitney test was used to statistically analyze the possible influence of the sex of the host on the group with the highest parasite richness and the greatest abundance of parasites. Simpson's diversity index was used to determine parasite diversity among the zoological groups of parasites of H. aff. malabaricus with the highest index. A total of 78 specimens of H. aff. malabaricus were examined. Among the zoological groups of metazoans found, the phylum Nematoda had the greatest number of species. Among these, the larval stage of Contracaecum sp. was most abundant. The sex of the host had a significant effect, with parasites more abundant in female fish (Z(U)=0.043; p<0.05). The digenean Parspina argentinensis, the nematodes Procamallanus (S.) iheringi, Rhabdochona acuminata and Hysterothylacium sp. and copepods Vaigamus sp. and Lernaea cyprinacea have not previously been recorded as parasites of H. aff. malabaricus.

Monogenoidea parasites of Cichla monoculus and Cichla pinima (Osteichthyes: Cichlidae), sympatric fish in lower Tapajós River, Northern Brazil

The study investigated the monogenoids infracommunity from the gills of Cichla monoculus and C. pinima living sympatrically in the lower Tapajós River, State of Pará (Brazil). A total of 561 monogenoids were collected of C. monoculus, which was host to seven species of these parasites, and 672 monogenoids were collected of C. pinima, which was host to eight species of these parasites. The monogenoids infracommunities of C. monoculus and C. pinima had a high qualitative similarity (88.0%), and quantitative (87%), and were composed by Gussevia arilla, G. longihaptor, G. tucunarense, G. undulata, Sciadicleithrum ergensi, S. umbilicum and S. uncinatum. There was a predominance of G. arilla and a low level of infection by Tucunarella cichlae. The prevalence, intensity and abundance of monogenoids were similar for C. monoculus and C. pinima, except for the intensity of G. undulata that was higher in C. monoculus. Parasite species displayed an aggregated dispersion, but G. longihaptor and S. ergensi exhibited random dispersion. This was the first study of monogenoids for C. pinima, and the first record of G. arilla, G. tucunarense, S. ergensi, S. umbilicum and S. uncinatum for C. monoculus. This study therefore extended the geographic distribution of these parasites to the lower Tapajós River in eastern Amazon.

Histopathological alterations in gills of Amazonian shrimp Macrobrachium amazonicum parasitized by isopod Probopyrus bithynis (Bopyridae).

The present study describes, for the first time, histopathological alterations in the gills of Macrobrachium amazonicum caused by infestation of Probopyrus bithynis (Isopoda: Bopyridae). In every case (100%), the infestation by P. bithynis was by a single pair of parasites (male and female) and occurred in the right or left side of the branchial chamber; the gill structures were visibly compressed due to the presence of parasites. The gills of M. amazonicum parasitized by P. bithynis exhibited a chronic inflammatory response, with the presence of edema, greater quantities of hemocytes, necrosis, epithelial cell hyperplasia, rupture of the pillar cells at the ends of the gill lamellae, desquamation of the cuticle, lamellar fusion and rupture of the lamellar epithelium. Tissue lesions were found in the histological sections of the gills of the parasitized M. amazonicum. Structural alterations in the branchial chamber of the hosts caused by the presence of P. bithynis can lead to physiological changes that can impair host respiratory performance. Finally, histopathological alterations in the branchial chamber of hosts suggest that P. bithynis feed directly on the gill tissues of this shrimp.

Supplementary taxonomic description of Demidospermus pinirampi (Monogenoidea, Dactylogyridae), with a new host record and an expansion of its distribution range / Descrição taxonômica complementar de Demidospermus pinirampi (Monogenoidea, Dactylogyridae), com registro de um novo hospedeiro e ampliação de sua área de distribuição

ABSTRACT During a survey conducted in the Lajeado Reservoir of the Tocantins River, in the state of Tocantins, Brazil, dactylogyrids were recovered from the gills of Pimelodina flavipinnis. Initial morphological analysis showed these dactylogyrids shared aspects of character with species of Demidospermus, with affinity to Demidospermus pinirampi, despite exhibiting differences with the original description by Kritsky et al. (1987) regarding the vagina, the base of the male copulatory organ and the shape and length of the bars. The analysis of the holotypes of D. pinirampi and its most morphologically close species, Demidospermus luckyi, revealed that these dactylogyrids were indeed D. pinirampi. This study therefore reports a new host and locality of occurrence, and reviews some measurements of the original description, supplementing and enhancing the morphological diagnosis of D. pinirampi.

RESUMO Durante um levantamento realizado no Reservatório de Lajeado, no Rio Tocantins, no estado de Tocantins, Brasil, dactilogirídeos foram recuperados das brânquias de Pimelodina flavipinnis. A análise morfológica inicial mostrou que esses dactilogirídeos compartilham aspectos de caráter com espécies de Demidospermus, com afinidade com Demidospermus pinirampi, apesar de apresentarem diferenças em relação à descrição original fornecida por Kritsky et al. (1987) com respeito à vagina, à base do órgão copulatório masculino e à forma e comprimento das barras. A análise dos holótipos de D. pinirampi e de sua espécie morfologicamente mais próxima, Demidospermus luckyi, revelou que estes dactilogirídeos eram realmente D. pinirampi. Este estudo, portanto, relata um novo hospedeiro e localidade de ocorrência e revisa algumas medidas da descrição original, complementando a diagnose morfológica de D. pinirampi.

Molecular phylogeny and ultrastructure of Myxobolus cf. cuneus, a parasite of patinga hybrid and Henneguya pseudoplatystoma, a parasite of pintado hybrid.

Through morphological, histopathological and ultrastructural analysis of Myxobolus cuneus Adriano, Arana et Cordeiro, 2006 and Henneguya pseudoplatystoma Naldoni, Arana, Maia, Ceccarelli, Tavares, Borges, Pozo et Adriano, 2009 were identified infecting pacu respectively (Piaractus mesopotamicus) and hybrid pintado (Pseudoplatystoma corruscans x Pseudoplatystoma reticulatum) taken from Brazilian fish farms. The present study describes 18S rDNA sequencing of Myxobolus cf. cuneus infecting the spleen of farmed patinga, a hybrid fish resulting from the crossing of P. mesopotamicus x Piaractus brachypomus, and H. pseudoplatystoma found in farmed hybrid pintado from the state of Sao Paulo, Brazil. The study also provides new details of the host-parasite interface of M. cf. cuneus, which reveal that the plasmodial wall is composed of a single membrane connected to the plasmodium ectoplasm by numerous pinocytic canals. The plasmodia also displayed asynchronous development but had disporic pansporoblasts at different developmental stages; immature and mature spores were found at different depth levels of the plasmodium. Maximum likelihood phylogenetic analysis showed that M. cf. cuneus appeared as a sister species of Henneguya pellucida Adriano, Arana et Cordeiro, 2005 in a sub-clade composed mainly of myxosporean parasites of characiforms, and that H. pseudoplatystoma clustered in a sub-clade composed of Henneguya/Myxobolus spp. parasites of siluriform fish.

Supplementary data of Henneguya leporinicola (Myxozoa, Myxosporea) a parasite of Leporinus macrocephalus from fish farms in the state of São Paulo, Brazil.

Henneguya leporinicola is a parasite of the gill filament of Leporinus macrocephalus, a characiform fish belonging to the Anostomidae family, which is of major economic importance. Despite the damage it causes in fish, little is known about this parasite. Therefore, a study was undertaken with fourteen specimens of L. macrocephalus taken from fish farms in the state of Sao Paulo. The fish were collected and examined searching for lesions and/or myxosporean plasmodia. One of the specimens (7.14%) contained white elongated plasmodia in the gill filament. The mature spores had elongated bodies with polar capsules of equal size and a caudal length greater than body length. Morphological characteristics identified the parasite as H. leporinicola. Molecular analysis of the 18S rDNA sequence resulted in a 1954 bp, demonstrating significant genetic differences with previously described species of Henneguya/Myxobolus. Phylogenetic analysis comparing the 18S rDNA sequence of H. leporinicola with other species, previously described in South America, and the 20 closest species as indicated by BLASTn Max Score showed H. leporinicola as a basal branch of a subclade composed by Henneguya spp. parasite of characiform hosts.

Prevalence, intensity, and phylogenetic analysis of Henneguya piaractus and Myxobolus cf. colossomatis from farmed Piaractus mesopotamicus in Brazil.

Henneguya piaractus and Myxobolus colossomatis (Myxosporea: Myxobolidae) are commonly found in the characid Piaractus mesopotamicus, an important fish farm species in Brazil. This paper describes the prevalence, mean intensity, molecular phylogeny, ultrastructure, and histology of H. piaractus and M. cf. colossomatis found infecting specimens of P. mesopotamicus collected from fish farms in the state of São Paulo, Brazil. A total of 278 fish were collected from 3 fish farms between February 2008 and July 2010. Parasite prevalence and mean intensity varied throughout the study period, and according to location and year. A phylogenetic tree, placing South American species in a global context, showed a clear tendency among myxosporean species to cluster according to host families. Ultrastructural analysis for M. cf. colossomatis showed the plasmodial wall with numerous projections toward host cells and phagocytic activity. Histopathological data showed hyperplasia caused by H. piaractus in highly infected fish. Histological and ultrastructural analysis of H. piaractus showed results similar to those that have previously been reported.