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The class Myxozoa consists of microscopic spores that typically present uniform morphological simplifications, containing one or two sporoplasms surrounded by valve cells. The present study analysed the morphological and phylogenetic characteristics of what proved to be a new species of Ceratomyxa found in the gallbladder of Mesonauta festivus Heckel, 1840 captured on the Piririm River in the municipality of Macapa, in Amapa state, Brazil. The fish were collected in gillnets, and were transported alive to Amapa State University in Macapa for the analysis of the organs. Crescent- or arch-shaped free spores were observed under light microscopy, containing two polar capsules and a suture line, which is typical of the morphology of the genus Ceratomyxa, contained within plasmodia that had snake-like movements. The gallbladder was conserved in 80% alcohol for the analysis of the 18S rDNA gene, and in Davidson solution for standardhistology. Ceratomyxa spores (n = 20) were observed in 11 of the 50 samplesanalysed, and thus had a prevalence of 22%, and had a mean length of 4.2 ± 0.5 µm, mean thickness of 22.75 ± 0.3 µm, and two polar capsules, 1.86 ± 0.3 µm long and 1.63 ± 0.1 µm thick. The phylogenetic analysis indicated that the new species forms a cluster with other freshwater Amazonian Ceratomyxa species, described previously. The new species represents the first description of a taxon of the genus Ceratomyxain fish from the Brazilian state of Amapa.

Nas regiões neotropicais, há estimativa de 9.100 espécies de peixes, e centenas de espécies novas são descritas anualmente, o qual a bacia amazônica abriga cerca de 2200 espécies de peixes corresponde a essa estimativa. Leporinus friderici é um peixe da ordem Characiformes conhecido popularmente como 'piau três pintas' ou 'aracú', trata-se de uma espécie abundante nas regiões neotropicais, que possui hábitos alimentares onívoros, se alimentando de material vegetal, detritos, frutos, sementes, camarão e pequenos peixes. É um peixe muito utilizado na alimentação pela qualidade de sua carne e é facilmente encontrado na região do Rio Matapí-AP. Foram realizadas coletas trimestrais durante setembro de 2015 a maio de 2016 e de agosto de 2017 a outubro de 2018, onde foram capturados 49 espécimes de L. friderici. A fauna de L. friderici foi bastante diversificada, sendo composta por macro e microparasitos, infectando brânquias, intestino, fígado, vesícula biliar, coração, nadadeira e baço do hospedeiro. Durante as análises foram encontrados quatro taxa, sendo eles: Nematoda, Platyhelminthes, Cnidaria (Myxozoa) e Ciliophora, e nove grupos de parasitos, Anisakidae gen. sp., Contracaecum sp., Dactylogyridae gen. sp., larvas de digenea (metacercária), Henneguya sp., Myxobolus sp., Ceratomyxa sp., Piscinoodinium pillulare, Ichthyophthirius multifiliis, Trichodina sp. e Chilodonella sp.. A ocorrência de micropasitos eucariotos foi a primeira registrada para L. friderici do estado do Amapá.

Objetivou-se nesse trabalho verificar a carga parasitária da espécie Satanoperca jurupari (Heckel,1840) e sua relação com a resposta bioquímica por meio da determinação dos teores de tióis totais (GSH) e dos produtos finais da lipoperoxidação, aspectos até então não estudados para a espécie e região. As coletas foram realizadas de outubro de 2017 à outubro de 2018, no rio Curiaú, zona rural da capital do Estado do Amapá. A análise de estresse oxidativo foi determinado após a homogenização do fígado de peixes da espécie Satanoperca jurupari, para determinar os produtos finais da peroxidação lipídicas (SRAT) e GSH. Para análise parasitológica, utilizou-se as técnicas de microscopia de luz (DIC e Histologia). Nos resultados obtidos do presente trabalho, há correlação negativa (-0,474) entre os teores de glutationa reduzida e SRAT, evidenciado níveis de estresse oxidativo moderados, com consumo de GSH e elevação dos teores de SRAT, porém não há ocorrência exacerbada de danos oxidativos às biomoléculas. Devido a carga parasitária é evidente o consumo de GSH de forma acentuada e a geração moderada de danos nos lipídeos de membrana causados pela infecção por parasitos. Foram identificados 3 gêneros do subfilo Myxoza: na vesícula biliar, Ceratomyxa e Ellipsomyxa, nas brânquias, Henneguya. Nas nadadeiras, tegumento, boca, brânquias, opérculo e olhos foi encontrado 1 representante do filo Microsporidia. Registrou-se pela primeira vez a ocorrência de microparasitas dos gêneros Ellipsomyxa e Ceratomyxa, e a segunda de Henneguya, assim como o primeiro registro de ocorrência de microsporídio para esta espécie. Com base em uma abordagem biológica integrada inferindo que a função de defesa antioxidante (GSH) e a oxidação dos lipídicos (SRAT) foram impactadas pela taxa de infecção, de forma sistêmica, sugerindo que funções hepáticas são alteradas. Estes resultados revelam a necessidade de maiores estudos referentes às características biológicas como detalhamento em microscopia eletrônica e biologia molecular para identificação e descrição a nível de espécie. O presente estudo forneceu também informações valiosas sobre efeitos de parasitas em uma espécie amazônica e sublinhou a importância da avaliação da associação dos marcadores de estresse oxidativo e a carga parasitária.

Federal Rural University of Amaz?nia. Paragominas, PA, Brazil. Federal Rural University of Amazonia. Carlos Azevedo Research Laboratory. Bel?m, PA, Brazil. Amap? State University. Laboratory of Morphophysiology and Animal Health. Macap?, AP, Brazil. Minist?rio da Sa?de. Secretaria de Vigil?ncia em Sa?de. Instituto Evandro Chagas. Laborat?rio de Epidemiologia e Imunologia Aplicada ? Leishmaniose. Ananindeua, PA, Brasil. Federal University of Par?. Laboratory of Biomolecular Technology. Bel?m, PA, Brazil. Federal Rural University of Amazonia. Carlos Azevedo Research Laboratory. Bel?m, PA, Brazil. 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 Par?, 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.

Fish are among the vertebrate groups most susceptible to parasitic infections due to environmental characteristics that can favor the development of parasites; also, position of the host in food web has been associated with the parasitism. The aim of this study was to investigate the ecology of parasites endohelminth in Metynnis lippincottianus from the Curiaú River, in eastern Amazon (Brazil), as well as to evaluate the parasite-host interactions. From 110 specimens of M. lippincottianus examined, 76.3% were infected by one or more parasite species, and a total of 146 parasites such as Procamallanus (Spirocamallanus) inopinatus (Nematoda), larvae of Contracaecum sp. (Nematoda) and Neoechinorhynchus pterodoridis (Acanthocephala) were collected in intestine. However, the dominance was of nematode species, and the parasites had uniform or random dispersion. The parasitic infracommunities showed low Shannon-Wiener diversity (0.2 ± 0.3), low evenness (0.2 ± 0.3) and low species richness of parasites (1.1 ± 0.8). The abundance of Contracaecum sp. presented a weak positive correlation with the weight of hosts, and relative condition factor was not affected by the parasitism. This first study about parasites of M. lippincottianus from Curiaí­­ River basin is the first report of N. pterodoridis for this host.

The present study describes a new coelozoic, eukaryotic microparasite of the genus Ellipsomyxa Køie, 2003 (Ceratomyxidae: Myxozoa) found parasitizing the gallbladder of Satanoperca jurupari Heckel, 1840 collected in the Curiaú River Environmental Protection Area in Macapá, Amapá state, Brazil. The fish were collected using mesh cast net. The gallbladders were examined, preserved in 80% alcohol for molecular analysis (SSU rDNA gene), and fixed in Davidson for histological slide preparation. The new parasite had a prevalence of 81% in the gallbladder, asymmetric plasmodia, irregular free spores in the bladder fluid, with no cyst formation. The spores are elliptical, with characteristics of the genus Ellipsomyxa, and they had a mean length of 10.11 (8.56-10.5) μm, mean width of 7.81 (5.96-9.56) μm, and thick walls. The polar capsules are sub-spherical in shape, slightly asymmetrical, with a mean length of 3.12 (2.31-3.99) μm and mean width of 2.5 (2.22-2.95) μm, containing polar filament with five or six coils perpendicular to the longitudinal axis of the capsule. The Bayesian Inference assigned the new species to a subclade formed by a lineage of Ellipsomyxa species from the Amazon region. Ellipsomyxa tucujuensis n. sp. is the sixth species of this genus described in fish from the Amazon region, and the first for the state of Amapá.

Infection of fish gills by Henneguya causes greater contact between the secondary gill lamellae, thereby giving rise to decreased absorption surface area at the end of the filaments. This ectoparasite can cause damages on the gills infected fish. In the present study, fresh gills of Metynnis lippincottianus were analyzed using optical microscopy techniques. The myxoporean Henneguya sp. was found to be infecting 80% of the gills of this host fish. Presence of this parasite caused hyperplasia and fusion of the gill lamellae, but without inflammation in the parasitized organ. Resumo A infecção de Henneguya nas brânquias de peixes causam o maior contato entres as lamelas branquiais secundárias. Provoca diminuição da superfície de absorção na extremidade dos filamentos, podendo ocasionar danos as brânquias dos peixes infectados. Neste estudo foram analisadas a fresco e com técnicas de microscopia de luz as brânquias de Metynnis lippincottianus. Foi determinada a presença de mixosporídeos Henneguya sp. infectando 80% das brânquias dos peixes hospedeiros. A presença desse ectoparasito causou hiperplasia e fusão das lamelas branquiais, porém sem inflamação no órgão parasitado.

This study describes Henneguya sacacaensis n. sp. in specimens of the Osteichthyes Satanoperca jurupari (Heckel, 1840), collected in the Rio Curiaú Environmental Protection Area in the city of Macapá, state of Amapá Brazil. Using optical microscopy and molecular analysis, these cyst-shaped parasites were analyzed. The gills of 57.14% of the analyzed S. jurupari contained hundreds of spores. The cysts found on the gill lamellae were oval-shaped and whitish. The Henneguya spores had an average length of 46.5 (41.3-56.92) µm. The fusiform body of the Henneguya measured 16.5 (13.16-20.01) µm long and 5.1 (3.91-6.12) µm in width, the two polar capsules had a taper of 3.83 (3.4-4.32) µm and a width of 1.68 (1.4-1.99) µm, and the tail measured 30 (22.47-41.67) µm in length, containing a polar filament coiled seven to nine times. Morphogical and phylogenetic analysis allowed the preposition of a new species, Henneguya sacacaensis n. sp, that belongs to the family Myxobolidae and the genus Henneguya. Resumo Henneguya sacacaensis n. sp. é descrito em espécimes do Osteichthyes Satanoperca jurupari (Heckel, 1840), coletados na área de Proteção Ambiental do rio Curiaú na cidade de Macapá no estado do Amapá, Brasil. Com auxílio de microscopia óptica e análises moleculares, esses parasitos foram analisados e observados nas brânquias em forma de cistos, contendo centenas de esporos e apresentaram a prevalência de 57,14%. Os cistos encontrados nas lamelas branquiais tinham formatos ovais e esbranquiçados. Seus esporos apresentaram um comprimento médio de 46,5 (41,3-56,92) µm, corpo fusiforme medindo 16,5 (13,16-20,01) µm de comprimento e 5,1 (3,91-6,12) µm de largura, suas duas cápsulas polares apresentam uma conicidade de 3,83 (3,4-4,32) µm e sua largura 1,68 µm (1,4-1,99), a cauda 30 (22,47-41,67) µm de comprimento, contento um filamento polar de 7 à 9 voltas. Análises morfológicas e filogenéticas permitiram a preposição de uma nova espécie, Henneguya sacacaensis n. sp, que pertence à família Myxobolidae e ao gênero Henneguya.

This study evaluated the in vitro and in vivo effects of the essential oil of Mentha piperita on monogeneans and its toxicity for Arapaima gigas . For the in vitro assay, gills of A. gigas naturally infected by Dawestrema cycloancistrium and Dawestrema cycloancistrioides were exposed to 0, 80, 160 and 320 mg L − 1 of M. piperita , which demonstrated anti-helminthic activity. In the toxicity test, A. gigas fingerlings were exposed to 0, 20, 40, 80, 100, 130 and 160 mg L − 1 of M. piperita to determine the lethal concentration (LC 50-4 h ), which was found to be 38 mg/L. Fish that had been exposed to 80, 100, 130 and 160 mg L − 1 presented epithelial elevations, fusion of the secondary lamellae, hypertrophy and aneurism. Necrosis was only observed at a concentration of 160 mg L − 1 of M. piperita . The in vitro results demonstrated that the anti-helminthic activity of M. piperita against Dawestrema spp. was dose dependent. However, baths with 40 mg L − 1 of essential oil of M. piperita were not effective against monogeneans in the gills of A. gigas . Therefore, since this anti-parasitic substance was in vitro effective and the concentrations used in the baths were not efficient and caused tissue alterations in the gills of the fish, other therapeutic strategies should be tested in order to increase the efficacy of this phytotherapeutic substance and reduce its toxicity for A. gigas . Finally, this study investigated the efficacy of M. piperita essential oil against parasites of A. gigas , for the first time. Statement of relevance This manuscript represents original article on the in vitro and in vivo effects of the essential oil of Mentha piperita on monogenoideans and its toxicity for Arapaima gigas , the giant fish from Amazon. Thus, this study investigated the efficacy of M. piperita essential oil against these parasites of A. gigas , for the first time

This study investigated the in vitro and in vivo anthelminthic efficacy, histopathological and hematological effects of Cymbopogon citratus essential oil (EO) in Colossoma macropomum. The major compounds of the essential oil were geranial (45.7%) and neral (33.9%). Essential oil was assayed at concentrations of 100, 200, 300, 400 and 500 mg L−1 for in vitro efficacy against monogeneans Anacanthorus spathulatus, Mymarothecium boegeri and Notozothecium janauachensis of C. macropomum. Two controls were considered for in vitro assays, one with the use of cultivation tank water and the other with cultivation tank water +70% alcohol. The concentration of 500 mg L−1 of the EO in vitro assays showed 100% efficacy against the parasites within 5 min of exposure, causing structural damages to their tegument. The 400 and 300 mg L−1 concentrations were 100% effective with 10 min and 30 min of exposure, respectively. The 200 mg L−1 concentration in vitro assays was also 100% effective within 30 min and the 100 mg L−1 treatment was 100% effective within 100 min of exposure. Total parasite mortality in both control groups occurred within 7 h. Efficacy was 47.1% after therapeutic baths of 20 min for three consecutive days with 60 mg L−1 of this EO. In addition, 60 mg L−1 of EO was the highest concentration tolerated by the fish and it had an anesthetic effect, and it caused increase in plasma glucose levels and decrease in leukocytes and lymphocytes number, as well as hyperplasia, lamellar fusion, detachment and aneurysm in C. macropomum gills. A low efficacy against the monogeneans was shown perhaps due to the low concentration of this EO tolerated by C. macropomum and the strategy used for the therapeutic baths, which may be corrected with a lower concentration of EO and more consecutive days for therapeutic baths.

a b s t r a c t The present study describes lesions caused by Kudoa sp. in the esophageal tissue of mapara catfishes (Hypophthalmus marginatus) collected from Cameta, Tocantins River in the northern Brazil. Fifty refriger- ated H. marginatus specimens were dissected and tissue samples were for embedded in paraffin and stained with hematoxylin-eosi, Masson's trichrome and Giemsa. Pseudocysts of whitish color were observed in the esophagus region. The parasites had four valves and other morphological characteristics of the genus Kudoa. Microscopic analysis revealed lesions in the mucosa, submucosa, and muscular layers. The Masson staining highlighted the presence of myxosporean cysts in the cytoplasm of the muscular fibers, and marked fibrosis of the muscular and mucous layers. The macro and microscopic findings of the present study confirm the presence of necrotic esophagitis in H. marginatus associated with infection by Kudoa. © 2015 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Este trabalho registra a ocorrencia espontânea de ameloblastoma em P. scalare. O tumor foi obtido a partir de um exemplar de Acara Bandeira, sendo fixado, seccionado, e os fragmentos processados para microscopia de luz e microscopia eletronica de varredura (MEV). O exame macroscopico evidenciou uma massa tumoral que se estendia do rebordo alveolar do maxilar superior a face externa labial. A MEV, a neoplasia apresentou uma serie de espiculas. Microscopicamente, percebia-se um processo neoplasico constituido por tecido conjuntivo de caracteristica mixoide, ricamente vascularizado, onde eram observados fragmentos de tecido osteoide. A amostra revelou proliferacao neoplasica do epitelio odontogenico, onde as celulas neoplasicas se organizavam na forma de palicada. Alteracoes histopatologicas em peixes tem sido uteis biomarcadores do efeito a exposicao a substâncias toxicas, sendo as neoplasias lesoes especificas, comumente encontradas em peixes de areas poluidas, revelando uma associacao entre as lesoes e a exposicao a irritantes.

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.

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.

Aspidogastrea are globally-distributed parasites of the class Trematoda, which have been described as pathogens of a range of aquatic organisms, in marine and freshwater environments. The principal morphological characteristic of the group is an adhesive ventral disc, which is responsible for fixing the parasite to the host organism. In this study, 112 specimens ofColomesus psittacus from the municipality of Cametá, in the state of Pará (Brazil), were necropsied. Platyhelminthes of the genus Rohdella attached to the mucous membrane of the fish's intestine by the adhesive disc were observed. Fragments of parasitized tissue were fixed in Davidson solution and then processed and stained with hematoxylin-eosin. Other fragments were fixed in glutaraldehyde, processed and observed under a scanning electron microscope. The prevalence of the parasite was 76.4%, mean intensity of infection was 8.0 and mean abundance was 6.2. The parasitism provoked chronic enteritis with diffused inflammatory infiltration. The adherence of the parasite to the mucous membrane of the intestine resulted in strangulation and hyperplasia of the region, as well as causing hypertrophy of the muscle of the mucous membrane. The present study describes the anatomopathological and ultrastructural aspects of the parasitism of the intestine of C. psittacus byRohdella sp. Os Aspidogastreas são parasitos da classe Trematoda, distribuídos globalmente e têm sido descritos como patógenos em uma gama de organismos aquáticos de ambientes marinhos e de água doce. A principal característica morfológica do grupo é um disco adesivo na região ventral responsável pela fixação do parasito no organismo hospedeiro. Neste estudo, 112 espécimes de Colomesus psittacus provenientes do município de Cametá, no estado do Pará (Brasil), foram necropsiados. Foram observados platelmintos do gêneroRohdella aderidos à mucosa intestinal através do disco adesivo. Fragmentos de tecido com parasito foram fixados em solução de Davidson e processados e corados em Hematoxilina-Eosina. Outros fragmentos foram fixados em glutaraldeído, processados e observados em microscopia eletrônica de varredura. A prevalência parasitária foi de 76, 4%, intensidade média de infecção de 8,0 e abundância média de 6,2. O parasitismo ocasionou uma enterite crônica com difuso infiltrado inflamatório. A fixação do parasito na mucosa intestinal provocou estrangulamento e hiperplasia da região, bem como hipertrofia da muscular da mucosa. O presente trabalho descreve os aspectos anatomopatológicos e ultra-estruturais da ação parasitária por Rohdella sp. no trato intestinal deC. psittacus.

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 Cameta, Para 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.

The Amazon estuary is a unique environment, in which a wide variety of both marine and freshwater fish species can be found, providing an important source of income for local populations. Forty G. broussonnetii specimens were collected from an area adjacent to the city of Salvaterra on Marajo Island, in the Brazilian state of Para, in 2011. The necroscopic analysis of the hosts revealed the presence of milky rounded cysts throughout the palate. Microscopic analysis of the parasitized fragments revealed that the squamous epithelium covering the palate was intact, although Myxobolus sp. cysts were observed in the cytoplasm of the striated skeletal muscles of the palate, as found in other myxosporids. Overall, the macro- and microscopic findings of the present study confirm the presence of necrotizing myositis in the palate of G. broussonnetii associated with parasitism by Myxobolus sp.

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. Um total de 40 exemplares do peixe teleósteo Gobioides grahamae Palmer & Wheeler, 1955 foram obtidos a partir do município de Salvaterra na Ilha de Marajó, no estado brasileiro do Pará. Os fígados foram removidos e processados para a microscopia de luz. De modo geral, 90% das amostras apresentavam algum grau de esteatose hepática, a qual foi invariavelmente associada com a presença de Microsporidium sp. O presente estudo confirma a ocorrência de esteatose em G. grahamae associada a infecções parasitárias por Microsporidium. Os resultados indicam que as condições de peixes saudáveis em ambiente natural podem ser afetadas negativamente por parasitas.

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.

In the present study, the cestoid Pterobothrium crassicolle Diesing, 1850 (Trypanorhyncha), was observed parasitizing specimens of the violet goby (Gobioides broussonnetii Lacepède, 1800) collected from the estuary of the Paracauarí River on Marajó Island in the north of the Brazilian state of Pará, between January 2009 and December 2010. Tissue samples were analyzed, which led to identification of blastocysts containing plerocercoid larvae. These larvae were processed for scanning electron microscopy. Sixty G. broussonnetii specimens were dissected, and P. crassicolle was found in 48 (80%) of them. The violet goby,G. broussonnetii, is a new host for P. crassicolle. No presente estudo, o cestóide Pterobothrium crassicolle Diesing, 1850 (Trypanorhyncha) é descrito parasitando espécimes do Peixe-dragão (Gobioides broussonnetii Lacepède, 1800), coletados no estuário do rio Paracauari na Ilha de Marajó no Norte do Estado do Pará, entre janeiro de 2009 e dezembro de 2010. Amostras de tecidos foram analisadas e blastocistos contendo larvas plerocercóides foram identificados. Estas larvas foram processadas para microscopia eletrônica de varredura. Sessenta espécimes de G. broussonnetii foram analisados, e P. crassicolle foi encontrado em 48 indivíduos (80%). Este é o primeiro registro de P. crassicolle parasitando o Peixe-dragão, G. broussonnetii.

O gênero Calyptospora possui espécies parasitas de peixes de água doce e marinha, e são frequentemente encontrados no fígado do hospedeiro. Este trabalho relata uma nova ocorrência e aspectos morfológicos de um coccídio hepatopancreático, em Cichla temensis da região nordeste paraense. Setenta espécimes do peixe C. temensis foram coletados no Rio Tocantins (Cametá-PA) e transportados ao Laboratório de Pesquisa Carlos Azevedo, sendo anestesiados e necropsiados para pesquisa de parasitos. Os fragmentos de tecidos parasitados foram fixados e processados para microscopia de luz (ML) e microscopia eletrônica de varredura (MEV). Os aspectos histológicos evidenciaram oocistos agrupados e isolados no parênquima hepático e pancreático. Diante dos achados macro e microscópicos da parasitose, apesar da grande carga parasitária presente na região hepatopancreática, não foi observado reação inflamatória significativa pelo hospedeiro. Este é o primeiro registro da ocorrência do parasitismo por Calyptospora sp. em hepatopâncreas de C. temensis no nordeste paraense.

A fish infecting myxosporean Ellipsomyxa gobioides n. sp. is described in the gallbladder of the Amazonian dragon fish Gobioides broussonnetii. Irregular disporous plasmodia (up to ~30 μm in diameter) with long branched and anastomosed pseudopodia were found attached to the gallbladder wall. Mature ellipsoid myxospores occurring floating in the bile measured 6.8 (6.5-7.0) μm (n = 30) long, 7.2 (6.9-7.5) μm (n = 15) wide, and 13.1 (12.8-13.5) (n = 25) thick. They had smooth thin valves elongated in the direction perpendicular to the plane of the straight central transverse sutural line. The two ellipsoidal polar capsules (PC) opened some distance from the sutural line on opposite sides, each measuring 4.6 (4.3-4.8) μm (n = 15) long and 2.5 (2.1-2.7) μm (n = 20) wide. Distance between PC 3.5 (3.1-3.8) μm (n = 15) in apical view. The polar filament was isofilar and consisted of a single coil with five or six turns. The objective of this study was to characterize this new species based on its morphological differences from the three previously described species. This is the first reported species of genus Ellipsomyxa from among the South American fauna.

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.