Kudoa rousseauxii n. sp. (Cnidaria: Multivalvulida) Infects the Skeletal Muscles of the Freshwater Fish Brachyplatystoma rousseauxii in the Amazon River.

PURPOSE: Members of the genus Kudoa Meglitsch, 1947 are known to infect the muscles of commercially important fishes worldwide, including those in the order Siluriformes. This paper describes the occurrence of a new species of Kudoa in the catfish Brachyplatystoma rousseauxii based on morphological study and molecular analysis of the ribosomal RNA gene (SSU rDNA). METHODS: Fifteen specimens of Brachyplatystoma rousseauxii were purchased from fishing zones near Mosqueiro Island, Belém, Pará, Brazil. After necropsy, tissue samples and cysts were analyzed using a stereomicroscope, and fresh slides were viewed under a light microscope to confirm parasitic infection. The tissue fragments were removed and processed for molecular and histological analyses. RESULTS: Microscopic pseudocysts were found in the epaxial region of skeletal muscle fibers in 80% of the analyzed specimens. The myxospores were quadrangular with four shell valves (SV), pyriform polar capsules (PC), and internal symmetry. Phylogenetic analyses indicated that the new species formed a cluster with the species previously described in the Amazon, being close to two freshwater species. CONCLUSIONS: Morphological differences and molecular data of SSU rDNA support that Kudoa rousseauxii n. sp. is a new species that infects B. rousseauxii, a freshwater fish with intense migratory cycles that is widely captured and consumed in the Amazon.

Hepatic coccidiosis in Serrasalmus rhombeus Linnaeus, 1766 from the Amazon basin: morphological and histopathological aspects.

Calyptospora species are coccids that commonly cause liver infections in fish all around the world. This paper describes the morphology and histopathological characteristics of liver infection caused by Calyptospora sp. in black piranha Serrasalmus rhombeus, from the Capim River, in the municipality of Ipixuna do Pará, state of Pará (Brazil). Specimens were collected, analyzed and necropsied and tissue fragments containing parasites were prepared for histology and scanning electron microscopy. Parasitism was detected in 33.0% of the analyzed specimens, which had spherical oocysts in the liver, with four pyriform sporocysts presenting sporozoites internally. A histological examination revealed oocysts positioned close to blood vessels, causing necrosis and degeneration of hepatic parenchyma, while the presence of mononuclear cell infiltrate and melanomacrophages indicated the onset of an inflammatory process. This is the first record of the genus Calyptospora in fish from the Capim River.

Myxobolus freitasi n. sp. (Myxozoa: Bivalvulida), a parasite of the brain of the electric knifefish in the Brazilian Amazon region.

A total of 30 specimens of the Amazonian electric knifefish, Brachyhypopomus beebei Schultz, 1944 (Gymnotiformes: Hypopomidae), were collected from the Peixe-Boi River in the state of Pará, Brazil (1°06'59" S; 47°18'26" W). Fragments of the brain tissue were extracted for analysis via optical microscopy, and 18 specimens (60%) presented microparasites of the genus Myxobolus, with unequal capsules. The spores were 18.6 µm (17.7-19.8 µm) long and 8.6 µm (8.4-9.0 µm) wide; the largest polar capsule was 13.0 µm (12.4-13.4 µm) long and 5.6 µm (5.3-6.0 µm) wide, and the smallest capsule was 5.0 µm (4.5-5.3 µm) long and 2.5 µm (2.3-2.6 µm) wide. Infected brain fragments were extracted for histological processing and staining with hematoxylin-eosin and Ziehl-Neelsen. Some fragments were conserved in ethanol for molecular genetics analysis. A partial sequence of the 18S DNA gene was obtained from the spores, which did not correspond to any other sequences deposited in GenBank, although it did form a clade with other Myxobolus parasites of the nervous system. The morphological data, together with molecular phylogeny, supported the designation of a new species Myxobolus freitasi n. sp.

Hepatic coccidiosis in Serrasalmus rhombeus Linnaeus, 1766 from the Amazon basin: morphological and histopathological aspects / Coccidiose hepática em Serrasalmus rhombeus Linnaeus, 1766 da Amazônia paraense: aspectos morfológicos e histopatológicos

Abstract Calyptospora species are coccids that commonly cause liver infections in fish all around the world. This paper describes the morphology and histopathological characteristics of liver infection caused by Calyptospora sp. in black piranha Serrasalmus rhombeus, from the Capim River, in the municipality of Ipixuna do Pará, state of Pará (Brazil). Specimens were collected, analyzed and necropsied and tissue fragments containing parasites were prepared for histology and scanning electron microscopy. Parasitism was detected in 33.0% of the analyzed specimens, which had spherical oocysts in the liver, with four pyriform sporocysts presenting sporozoites internally. A histological examination revealed oocysts positioned close to blood vessels, causing necrosis and degeneration of hepatic parenchyma, while the presence of mononuclear cell infiltrate and melanomacrophages indicated the onset of an inflammatory process. This is the first record of the genus Calyptospora in fish from the Capim River.

Resumo Calyptosporídeos são coccídeos constantemente encontrados causando infecções hepáticas em peixes de todo o planeta. Este estudo descreve a morfologia e características histopatológicas da infecção hepática causada por Calyptospora sp. encontrados em Serrasalmus rhombeus, a piranha negra, oriunda do rio Capim, em Ipixuna do Pará, Brasil. Os animais foram coletados, analisados e necropsiados; fragmentos teciduais com a presença dos parasitos foram processados para histologia e microscopia eletrônica de varredura. O parasitismo ocorreu em 33,0% dos espécimes analisados, onde foram encontrados oocistos esféricos no fígado, com esporocistos piriformes, apresentando internamente esporozoítos. No exame histológico, os oocistos estavam dispostos próximos aos vasos sanguíneos, causando necrose e degeneração do parênquima hepático; a presença de infiltrado de células mononucleares e melanomacrófagos indicaram o início de um processo inflamatório. Este é o primeiro registro do gênero Calyptospora em peixes do rio Capim.

Myxobolus freitasi n. sp. (Myxozoa: Bivalvulida), a parasite of the brain of the electric knifefish in the Brazilian Amazon region / Myxobolus freitasi n. sp. (Myxozoa: Bivalvulida), parasita do cérebro do peixe-faca elétrico na Amazônia brasileira

Abstract A total of 30 specimens of the Amazonian electric knifefish, Brachyhypopomus beebei Schultz, 1944 (Gymnotiformes: Hypopomidae), were collected from the Peixe-Boi River in the state of Pará, Brazil (1°06'59" S; 47°18'26" W). Fragments of the brain tissue were extracted for analysis via optical microscopy, and 18 specimens (60%) presented microparasites of the genus Myxobolus, with unequal capsules. The spores were 18.6 µm (17.7-19.8 µm) long and 8.6 µm (8.4-9.0 µm) wide; the largest polar capsule was 13.0 µm (12.4-13.4 µm) long and 5.6 µm (5.3-6.0 µm) wide, and the smallest capsule was 5.0 µm (4.5-5.3 µm) long and 2.5 µm (2.3-2.6 µm) wide. Infected brain fragments were extracted for histological processing and staining with hematoxylin-eosin and Ziehl-Neelsen. Some fragments were conserved in ethanol for molecular genetics analysis. A partial sequence of the 18S DNA gene was obtained from the spores, which did not correspond to any other sequences deposited in GenBank, although it did form a clade with other Myxobolus parasites of the nervous system. The morphological data, together with molecular phylogeny, supported the designation of a new species Myxobolus freitasi n. sp.

Resumo Um total de 30 espécimes do peixe-faca elétrico da Amazônia, Brachyhypopomus beebei Schultz, 1944 (Gymnotiformes: Hypopomidae), foram coletados no rio Peixe-Mani, no estado do Pará, Brasil (1 ° 06'59 "S; 47 ° 18 ' 26 "W). Fragmentos de tecido cerebral foram extraídos para análise em microscopia óptica, sendo que 18 espécimes (60%) apresentavam microparasitos do gênero Myxobolus, com cápsulas desiguais. Os esporos apresentavam 18,6 µm (17,7-19,8 µm) de comprimento e 8,6 µm (8,4-9,0 µm) de largura; a maior cápsula polar tinha 13,0 µm (12,4-13,4 µm) de comprimento e 5,6 µm (5,3-6,0 µm) de largura, e a menor cápsula tinha 5,0 µm (4,5-5,3 µm) de comprimento e 2,5 µm (2,3-2,6 µm) de largura. Fragmentos cerebrais infectados foram extraídos para processamento histológico e coloração com hematoxilina-eosina e Ziehl-Neelsen. Alguns fragmentos foram conservados em etanol para análise genética molecular. Dos esporos, foi obtida uma sequência parcial do gene 18S do DNA, que não correspondeu a nenhuma outra sequência depositada no GenBank, embora tenha formado um clado com outros parasitas do gênero Myxobolus do sistema nervoso. Os dados morfológicos, juntamente com a filogenia molecular, apoiaram a designação de uma nova espécie Myxobolus freitasi n. sp.

Henneguyosis in gills of Metynnis hypsauchen: an Amazon freshwater fish.

This study describes aspects of infection caused by Myxozoa of the genus Henneguya sp. in gills of fish belonging to the species Metynnis hypsauchen. Two sampling were made in the Capim river, close to the Ribeira community, in the municipality of Ipixuna do Pará, State of Pará, Brazil, during the months of August 2018 and March 2019. The animals were captured and transported live to the Laboratório de Pesquisa Carlos Azevedo, at the Universidade Federal Rural da Amazônia (UFRA), in Belém, Pará, Brazil. The animals were examined, and after parasitism was confirmed, Differential Interference Contrast Microscopes were used, to evaluate the parasite spores. Ziehl-Neelsen stain techniques were used in histology. Necroscopic analyses of Metynnis hypsauchen specimens found parasites in 80% of the hosts (16/20), with whitish-colored cysts in the branchial filaments, containing mature spores of the genus Henneguya. The histopathological analysis indicated large areas with cystic lesions with associated ischemic necrosis. The descriptions from this study indicate that the parasite drastically compromises the host's respiratory system. Additionally, it is worth noting that parasite fauna studies of fishes in the Capim river are still a vast topic for research; this is the first record of infection by Henneguya sp. in Metynnis hypsauchen, captured in the Capim river in Ipixuna do Pará.

Renal myxoboliosis of Metynnis hypsauchen in the Brazilian Amazon: morphological and histopathological aspects

In their natural habitat, fish are constantly threatened by icthyoparasites, notably those from the Phylum Cnidaria, Hatschek, 1888, represented by species of the Myxozoa, responsible for infections in fish that cause complications to their health that can lead to death. Among these parasites, the genus Myxobolus Butschli, 1882 is responsible for the largest number of infections described in fishes from the Americas. This study describes the morphological and histopathological aspects of parasitism by Myxobolus sp. in specimens of Metynnis hypsauchen, obtained from the Capim river, in the municipality of Ipixuna do Pará, Pará, Brazil. During the months of August and March, 2018, 20 animals were captured, euthanized and autopsied. With the aid of a stereomicroscope an external and internal investigation was performed on the animals for the purpose of finding lesions or parasitic cysts, followed by confirmation of infection in Light Microscopy (ML). Cysts and Fragments from parasitized tissues were processed using techniques for histology and Scanning Electron Microscopy (SEM). For histology they were stained with Hematoxylin-Eosin (H-E) and Ziehl-Neelsen and for SEM Micrographs were captured, using equipment from the Museu Paraense Emílio Goeldi. The prevalence of parasitism was 60% (12/20) of the specimens, and the cysts were in the epithelium and lumen of the renal tubules, causing histopathological changes. The characteristics of the parasite spores are those associated with the genus Myxobolus, with an ellipsoid format, two polar capsules and a sporoplasm region. It was possible to confirm a high parasite load of Myxobolus, with compromised renal functions. This study is the first to describe Myxospore in Metynnis hypsauchen.

Kudoa amazonica n. sp. (Myxozoa; Multivalvulida), a parasite of the esophageal musculature of the freshwater catfish, Hypophthalmus marginatus (Siluriformes: Pimelodidae), from a river of the Amazon region.

The class Myxozoa is a group of spore-producing eukaryote organisms that parasitize both freshwater and marine fish. The multivalvulide myxosporidian parasites of the genus Kudoa infect primarily the musculature of the fish host, some species are producing enzymes (proteases) capable of digesting muscle fibers. In the present study, 50 specimens of the freshwater catfish Hypophthalmus marginatus were collected from the Tocantins River in Pará, Brazil, and were analyzed. Overall, 68% of these specimens presented infections by Kudoa parasite in the esophageal musculature. The morphology of these parasite was examined under light microscopy and nucleotide sequences of the SSU rDNA gene were obtained for phylogenetic analyses. The species formed numerous whitish pseudocysts containing square spores with rounded extremities in the apical view, and four polar capsules of equal size. In the phylogenetic analyses, Kudoa amazonica n. sp. was characterized as a sister taxon of another freshwater species, Kudoa orbicularis. The combination of morphological, morphometric, and molecular data obtained in the present study provided a conclusive diagnosis of Kudoa amazonica n. sp., which is clearly distinct from all other Kudoa taxa described to date.

Lymphocytic meningoencephalomyelitis associated with Myxobolus sp. (Bivalvulidae: Myxozoa) infection in the Amazonian fish Eigenmannia sp. (Sternopygidae: Gymnotiformes) / Meningoencefalomielite linfocitária associada à infecção por Myxobolus sp. (Bivalvulidae:Myxozoa) em peixe amazônico Eigenmannia sp. (Sternopygidae: Gymnotiformes)

Abstract The genus Myxobolus, parasites that infect fishes, which cause myxobolosis, includes spore organisms belonging to the phylum Myxozoa and represents approximately 36% of all species described for the entire phylum. This study describes lymphocytic meningoencephalomyelitis associated with Myxobolus sp. infection in the brain and spinal cord (the central nervous system, CNS) of Eigenmannia sp., from the Amazon estuary region, in the Administrative District of Outeiro (DAOUT), Belém, Pará, Brazil. In May and June 2015, 40 Eigenmannia sp. specimens were captured from this region and examined. The fish were anesthetized, slaughtered and dissected for sexing (gonad evaluation) and studying parasites and cysts; after diagnosing the presence of the myxozoans using a light microscope, small fragments of the brain and spinal cord were removed for histological processing and Hematoxylin-Eosin and Ziehl-Neelsen staining. Histopathological analysis of the brain and spinal cord, based on histological sections stained with Hematoxylin-Eosin, pronounced and diffuse edema in these tissues, and congestion, degeneration, and focal necrosis of the cerebral cortex. The present study describes lymphocytic meningoencephalomyelitis associated with infection by Myxobolus sp. in the central nervous system of Eigenmannia sp.

Resumo O gênero Myxobolus é composto por parasitas esporais que podem infectar peixes e causar a “myxobolose”. São organismos pertencentes ao filo Myxozoa e representam cerca de 36% do total de espécies descritas para todo o Filo. Este estudo descreve meningoencefalomielite linfocitária, associada à infecção por Myxobolus sp. no cérebro e medula espinhal (SNC) de Eigenmannia sp, oriundo de região estuarina amazônica, no Distrito Administrativo de Outeiro (DAOUT), município de Belém, Pará, Brasil. Foram capturados e examinados 40 espécimes de Eigenmannia sp. entre os meses de maio e junho de 2015. Os peixes foram anestesiados, abatidos e dissecados para sexagem (avaliação das gônadas) e pesquisa de parasitos e cistos. Após o diagnóstico da presença dos mixosporidios, utilizando-se microscópio de luz, pequenos fragmentos do cérebro e da medula espinal foram removidos para processamento histológico e coloração por Hematoxilina-Eosina e coloração especial em Ziehl-Neelsen. A análise histopatológica do cérebro e da medula espinhal, com base em cortes histológicos corados com Hematoxilina-Eosina, mostrou edema difuso nesses tecidos, e congestão, degeneração e necrose focal do córtex cerebral. O presente estudo descreve meningoencefalomielite linfocítica, associada à infecção por Myxobolus sp., no sistema nervoso central de Eigenmannia sp.

Lymphocytic meningoencephalomyelitis associated with Myxobolus sp. (Bivalvulidae: Myxozoa) infection in the Amazonian fish Eigenmannia sp. (Sternopygidae: Gymnotiformes).

The genus Myxobolus, parasites that infect fishes, which cause myxobolosis, includes spore organisms belonging to the phylum Myxozoa and represents approximately 36% of all species described for the entire phylum. This study describes lymphocytic meningoencephalomyelitis associated with Myxobolus sp. infection in the brain and spinal cord (the central nervous system, CNS) of Eigenmannia sp., from the Amazon estuary region, in the Administrative District of Outeiro (DAOUT), Belém, Pará, Brazil. In May and June 2015, 40 Eigenmannia sp. specimens were captured from this region and examined. The fish were anesthetized, slaughtered and dissected for sexing (gonad evaluation) and studying parasites and cysts; after diagnosing the presence of the myxozoans using a light microscope, small fragments of the brain and spinal cord were removed for histological processing and Hematoxylin-Eosin and Ziehl-Neelsen staining. Histopathological analysis of the brain and spinal cord, based on histological sections stained with Hematoxylin-Eosin, pronounced and diffuse edema in these tissues, and congestion, degeneration, and focal necrosis of the cerebral cortex. The present study describes lymphocytic meningoencephalomyelitis associated with infection by Myxobolus sp. in the central nervous system of Eigenmannia sp.

Henneguya paraensis n. sp. (Myxozoa; Myxosporea), a new gill parasite of the Amazonian fish Cichla temensis (Teleostei: Cichlidae): morphological and molecular aspects.

The present study describes light microscopy, transmission electron microscopy, and molecular analyses of a myxosporid found parasitizing the gill region of the teleost fish Cichla temensis, collected from the Tocantins River, near Cametá, Pará State, Brazil. The prevalence of infection was 60 %. The spore-containing cysts that were located in the gill lamellae were oval and whitish. The spores had a mean length of 42.3 ± 0.65 µm; fusiform body, 12.8 ± 0.42-µm long and 8.6 ± 0.32-µm wide; each of the two valves exhibited a tapering tail of 29.5 ± 0.73 µm length. The spores had two polar capsules, 7.4 ± 0.16-µm long by 2.6 ± 0.08-µm wide, containing a polar filament with 5-7 twists. The spores differ from the species previously described, and phylogenetic analysis based on spore morphology and molecular aspects indicated that the fish parasite Henneguya sp. has a strong trend to form clades mainly based on the environment and host order/family. Thus, we conclude that the species belongs to the family Myxobolidae, genus Henneguya, which comprises a new species: Henneguya paraensis n. sp.

Infection by Henneguya sp. (Myxozoa) in the bone tissue of the gill filaments of the Amazonian catfish Hypophthalmus marginatus (Siluriformes).

This study describes aspects of the infection caused by the myxosporean genus Henneguya, which forms cysts in the bony portion of the gill filaments of Hypophthalmusmarginatus. Specimens of this catfish were acquired dead from artisanal fishermen near the town of Cametá, state of Pará, northern Brazil, between July 2011 and May 2012. They were transported in refrigerated containers to the Carlos Azevedo Research Laboratory at the Federal Rural University of Amazonia, in Belém, where analyses were performed. After confirmation of parasitism by the genus Henneguya, observation were made using optical and differential interference contrast (DIC) microscopy. The histological technique of embedment in paraffin was used. Ziehl-Neelsen staining was applied to the histological sections. Necropsy analyses on specimens of H. marginatus showed that 80% of them (40/50) had cysts of whitish coloration inside the bony portion of the gill filaments, filled with Henneguya spores. The present study found inflammatory infiltrate in the vicinity of the cysts. Furthermore, the special Ziehl-Neelsen staining technique made it possible to mark the Henneguya sp. cysts in the bone tissue and in spore isolates in the gill tissue structure. The descriptions of these histopathological findings show that this parasite is very invasive and causes damage to its host tissues.

Kudoa spp. (Myxozoa) infection in musculature of Plagioscion squamosissimus (Sciaenidae) in the Amazon region, Brazil.

Ninety specimens of Plagioscion squamosissimus captured using fishing tackle in the Outeiro district, state of Pará, were examined. Fish were placed in plastic bags containing water, under conditions of artificial aeration, and transported live to the Carlos Azevedo Research Laboratory (LPCA), in Belém, Pará. They were anesthetized, euthanized and necropsied; small fragments of the epaxial and hypaxial muscles were removed for examination of fresh histological sections by means of optical microscopy. In 100% of the specimens analyzed, parasitic pseudocysts were seen to be interspersed within and between the skeletal muscle. These contained pseudoquadrate and/or star-shaped spores that presented four valves and four polar capsules, which were identified from their morphology as belonging to the genus Kudoa. This is the first report of Kudoa in P. squamosissimus in the Amazon region, Pará, Brazil.

Kudoa spp. (Myxozoa) infection in musculature of Plagioscion squamosissimus (Sciaenidae) in the Amazon region, Brazil / Infecção por Kudoa spp. (Myxozoa) na musculatura de Plagioscion squamosissimus (Sciaenidae) da região amazônica, Brasil

Ninety specimens of Plagioscion squamosissimus captured using fishing tackle in the Outeiro district, state of Pará, were examined. Fish were placed in plastic bags containing water, under conditions of artificial aeration, and transported live to the Carlos Azevedo Research Laboratory (LPCA), in Belém, Pará. They were anesthetized, euthanized and necropsied; small fragments of the epaxial and hypaxial muscles were removed for examination of fresh histological sections by means of optical microscopy. In 100% of the specimens analyzed, parasitic pseudocysts were seen to be interspersed within and between the skeletal muscle. These contained pseudoquadrate and/or star-shaped spores that presented four valves and four polar capsules, which were identified from their morphology as belonging to the genus Kudoa. This is the first report of Kudoa in P. squamosissimus in the Amazon region, Pará, Brazil.

Foram observados 90 exemplares de P. squamosissimus, capturados com apetrechos de pesca no distrito de Outeiro, estado do Pará. Os animais foram acondicionados em sacos plásticos com água do habitat e aeração artificial, transportados vivos até o Laboratório de Pesquisa Carlos Azevedo (LPCA), em Belém-PA. Foram anestesiados, eutanasiados e necropsiados; pequenos fragmentos da musculatura epi e hipoaxial foram retirados para observação, a fresco e para histologia em microscopia de luz (ML). Em 100% dos exemplares analisados, foi observada a presença de pseudocistos parasitários entremeados, dentro e entre as fibras musculares estriadas esqueléticas, onde observou-se a presença de esporos de formato pseudoquadrado e/ou estrelado, com quatro valvas e quatro cápsulas polares, sendo identificados pela sua morfologia como pertencentes ao gênero Kudoa. Este é o primeiro relato de Kudoa em P. squamosissimus na Amazônia, Pará, Brasil.

Potaspora aequidens n. sp. (Microsporidia, Tetramicridae), a parasite infecting the freshwater fish Aequidens plagiozonatus (Teleostei, Cichlidae) from Brazil.

Morphological and molecular procedures were used to describe a new species of microsporidian that infects the muscles of the sub-opercular region and the caudal fins of the freshwater Aequidens plagiozonatus in Brazil. This microsporidian forms whitish xenomas containing variable number of spores, reaching up to ~0.4 mm in diameter. The mature spores, pyriformin shape, with slightly round ends, measured 3.4 ± 0.5 µm long and 1.9 ± 0.3 µm wide (n = 50) and showed characteristics typical of Microsporidia. The average thickness of the spore wall was 100 (96-108) nm (n = 50), and the spore wall was composed of two layers, a thin, electron-dense exospore and a thick electron-transparent endospore. The exospore was surrounded by a thin, irregular layer of granular material. The anchoring disc was mushroom-like, located in the apical region of the spore in an eccentric position relative to the spore axis, rendering bilateral asymmetry to the spore. The anterior part of the polar filament (PF) (manubrium) measured approximately 125 (122-128) nm thick (n = 30), and the angle of tilt between the anterior PF and the spore axis was ~45°; the posterior part was packed in 8-9 coils. Phylogenetic analysis showed a strongly supported clade containing family Spragueidae Weissenberg, 1976, family Tetramicridae Matthews and Matthews, 1980, Microsporidium sp. RBS1, and Kabatana spp. In conclusion, the available morphological, ultrastructural, and molecular data shows that this microsporidian is a new species belonging to group 4, classified as Potaspora aequidens n. sp. This is the second species described in the genus Potaspora.

Morphological aspects of Henneguya aequidens n. sp. (Myxozoa: Myxobolidae) in Aequidens plagiozonatus Kullander, 1984 (Teleostei: Cichlidae) in the Amazon region, Brazil.

A new species of Myxosporea, Henneguya aequidens sp. n. (Myxozoa: Myxobolidae), was described based on its ultrastructural features. This is a parasite of the freshwater fish Aequidens plagiozonatus, in the Peixe-boi River, Pará, Brazil. This parasite was found in the gills, in the form of whitish ellipsoid cysts with mature spores inside them. The average spore body was 15 ± 0.9 µm in length (n = 30) and 6 ± 0.8 µm in width (n = 30), and the tail measured 27 ± 0.5 µm in length (n = 15). The spores showed typical features of the genus Henneguya with two valves of equal size and two symmetrical polar capsules of 3 ± 0.3 µm in length and 2 ± 0.3 µm in width. Each polar capsule had a polar filament forming a helix from the apical region to the polar caps, with four to six turns. Based on the ultrastructural differences in morphology of these spores, the location of the parasite, and its host specificity, this parasite was described as a new species.

Infection by Henneguya sp. (Myxozoa) in the bone tissue of the gill filaments of the Amazonian catfish Hypophthalmus marginatus (Siluriformes) / Infecção por Henneguya sp. (Myxozoa) em tecido ósseo do filamento branquial do bagre amazônico Hypophthalmus marginatus (Siluriformes)

This study describes aspects of the infection caused by the myxosporean genus Henneguya, which forms cysts in the bony portion of the gill filaments of Hypophthalmusmarginatus. Specimens of this catfish were acquired dead from artisanal fishermen near the town of Cametá, state of Pará, northern Brazil, between July 2011 and May 2012. They were transported in refrigerated containers to the Carlos Azevedo Research Laboratory at the Federal Rural University of Amazonia, in Belém, where analyses were performed. After confirmation of parasitism by the genus Henneguya, observation were made using optical and differential interference contrast (DIC) microscopy. The histological technique of embedment in paraffin was used. Ziehl-Neelsen staining was applied to the histological sections. Necropsy analyses on specimens of H. marginatus showed that 80% of them (40/50) had cysts of whitish coloration inside the bony portion of the gill filaments, filled with Henneguya spores. The present study found inflammatory infiltrate in the vicinity of the cysts. Furthermore, the special Ziehl-Neelsen staining technique made it possible to mark the Henneguya sp. cysts in the bone tissue and in spore isolates in the gill tissue structure. The descriptions of these histopathological findings show that this parasite is very invasive and causes damage to its host tissues.

O presente estudo descreve os aspectos da infecção causada por mixosporídio do gênero Henneguya, formando cistos na porção óssea dos filamentos branquiais de Hypophthalmus marginatus. Espécimes desse bagre foram adquiridos mortos de pescadores artesanais perto da cidade de Cametá, Estado do Pará, Brasil, entre julho de 2011 e maio de 2012. Os animais foram transportados em contêineres refrigerados até o Laboratório de Pesquisa Carlos Azevedo, na Universidade Federal Rural da Amazônia, em Belém, onde se procederam as análises. Após a constatação do parasitismo pelo gênero Henneguya, foi realizada a observação em microscópio óptico e em microscópio de contraste de interferência diferencial (DIC). Foi realizada técnica histológica de impregnação em parafina e coloração dos cortes histológicos em Ziehl-Neelsen. As análises necroscópicas dos espécimes de H. marginatus revelaram que 80% (40/50) destes apresentavam cistos esbranquiçados na porção óssea dos filamentos branquiais, repletos de esporos do gênero Henneguya. O presente estudo revelou infiltrado inflamatório nas imediações dos cistos. Além disso, a técnica especial de coloração em Ziehl-Neelsen possibilitou marcar os cistos de Henneguya sp. no tecido ósseo e de esporos isolados na estrutura de tecido branquial. As descrições desses achados histopatológicos mostram que esse parasita é muito invasivo e produz danos aos seus tecidos do hospedeiro.

Infection of the heart of Pimelodus ornatus (Teleostei, Pimelodidae), by Myxobolus sp. (Myxozoa, Myxobolidae).

The phylum Myxozoa Grassé, 1970, consists of a heterogenous group of around 50 genera that are worldwide disseminated in a wide variety of aquatic media. In the present study, 43 specimens of Pimelodus ornatus were collected from an adjacent area to the Cachoeira do Arari municipality on Marajó Island, in the Brazilian state of Pará, in 2013. Macroscopic analysis showed the presence of whitened plasmodia located in the cardiac muscle and also in the region between the bulbus arteriosus and atrium cordis. Microscopic analysis on the parasitized tissues revealed spores that were typically piriform, with the anterior portion slightly narrower than the posterior end. The spore valves were symmetrical. The present species is placed in the genus Myxobolus Butschli, 1882, because of the presence of a pair of equal polar capsules in each spore. The prevalence of parasitism observed was 13.9% (6/43). This research note reports the first occurrence of Myxobolus as a parasite of the heart in the teleostean fish P. ornatus in the Amazon region and confirms the occurrence of secondary myocarditis in this fish, caused by parasitism by Myxobolus sp. The rarity of this parasitic species of Myxobolus at this tissue site, associated with other spore morphology characteristics in the fish, suggests that it is an undescribed species.

Infection of the heart of Pimelodus ornatus (Teleostei, Pimelodidae), by Myxobolus sp. (Myxozoa, Myxobolidae) / Infecção do tecido cardíaco de Pimelodus ornatus (Teleostei, Pimelodidae), por Myxobolus sp. (Myxozoa, Myxobolidae)

The phylum Myxozoa Grassé, 1970, consists of a heterogenous group of around 50 genera that are worldwide disseminated in a wide variety of aquatic media. In the present study, 43 specimens of Pimelodus ornatus were collected from an adjacent area to the Cachoeira do Arari municipality on Marajó Island, in the Brazilian state of Pará, in 2013. Macroscopic analysis showed the presence of whitened plasmodia located in the cardiac muscle and also in the region between the bulbus arteriosus and atrium cordis. Microscopic analysis on the parasitized tissues revealed spores that were typically piriform, with the anterior portion slightly narrower than the posterior end. The spore valves were symmetrical. The present species is placed in the genus Myxobolus Butschli, 1882, because of the presence of a pair of equal polar capsules in each spore. The prevalence of parasitism observed was 13.9% (6/43). This research note reports the first occurrence of Myxobolus as a parasite of the heart in the teleostean fish P. ornatus in the Amazon region and confirms the occurrence of secondary myocarditis in this fish, caused by parasitism by Myxobolus sp. The rarity of this parasitic species of Myxobolus at this tissue site, associated with other spore morphology characteristics in the fish, suggests that it is an undescribed species.

O filo Myxozoa Grassé, 1970, consiste em um grupo heterogêneo de cerca de 50 gêneros que são disseminados em todo o mundo em uma grande variedade de meios aquáticos. No presente estudo, quarenta e três espécimes de Pimelodus ornatus foram coletados a partir de uma área adjacente à cidade de Cachoeira do Arari, na Ilha do Marajó, no Estado do Pará, em 2013. À análise macroscópica verificou-se a presença de plasmódios esbranquiçados, localizados no músculo cardíaco e também na região entre o bulbus arteriosus e o atrium cordis. A análise microscópica dos tecidos parasitados revelou esporos que eram tipicamente piriformes, com a porção anterior um pouco mais estreita do que a extremidade posterior, sendo suas válvulas simétricas. A prevalência do parasitismo observada foi de 13,9% (6/43). Esta nota de pesquisa relata a primeira ocorrência de Myxobolus como um parasita do coração no peixe teleósteo P. ornatus, na Região Amazônica e, confirma a ocorrência de miocardite secundária causada por esse parasitismo. A raridade da ocorrência de Myxobolus sp. neste tecido, associado a outras características morfológicas dos esporos no peixe, sugere que é uma espécie não descrita.

Hepatic steatosis associated with microsporidiosis in teleost fishes from Marajó Island, Brazil.

A total of 40 specimens of the teleost fish Gobioides grahamae Palmer & Wheeler, 1955 were obtained from the municipality of Salvaterra on Marajó Island in the Brazilian state of Pará. Their livers were removed and processed for light microscopy. Overall, 90% of the specimens presented some degree of steatosis of the liver, which was invariably associated with the presence of Microsporidium sp. The present study confirms the occurrence of steatosis in G. grahamae associated with parasitic infections by Microsporidium. The findings indicate that the condition of otherwise healthy fishes in their natural environment may be affected negatively by parasites.