Morphological features and molecular phylogeny of Hoferellus azevedoi n. sp. (Myxozoa: Myxobilatidae) found in Chaetobranchus flavescens Heckel, 1840 (Teleostei: Cichlidae) from Marajó Island, northern Brazil.

Hoferellus azevedoi n. sp. was found in the urinary bladder of Chaetobranchus flavescens Heckel, 1840 from the Arari River on Marajó Island in Pará, Brazil. This is the first record of a species of the genus Hoferellus in a host from the Brazilian Amazon region. The new species has disporous and polysporous plasmodia, which vary in size and shape, with some being found adhered to the epithelium of the urinary bladder, and others floating in the liquid. The mature spores are sub-spherical in the sutural view, with a number of peripheral projections around the whole surface of the spore. In the sutural view, the spores are 5.3 ± 0.2 (5.2-5.6) µm in length and 7.0 ± 0.7 (6.3-7.7) µm in width, with two piriform polar capsules of equal size, 2.5 ± 0.2 (2.3-2.8) µm long and 1.8 ± 0.2 (1.6-2.0) µm wide. Based on a partial (1312 bps) sequence of the SSU rDNA gene, Hoferellus azevedoi n. sp. was distinguished from all the other myxozoan species deposited in GenBank. Phylogenetically, based on Bayesian inference and p-distances, the new species was allocated to the "Freshwater Urinary-Bladder" clade, together with other myxozoan parasites of the excretory system. Based on the morphological data, supported by the partial sequence of the SSU rDNA gene, we describe a new species of myxozoan, Hoferellus azevedoi n. sp.

Ellipsomyxa arariensis n. sp. (Myxozoa: Ceratomyxidae), a new myxozoan parasite of Pygocentrus nattereri Kner, 1858 (Teleostei: Characidae) and Pimelodus ornatus Kner, 1858 (Teleostei: Pimelodidae) from Marajó Island, in the Brazilian Amazon region.

Ellipsomyxa arariensis n. sp. was found in the gallbladder of Pygocentrus nattereri Kner, 1858 and Pimelodus ornatus Kner, 1858 from the Arari River on Marajó Island in Pará, Brazil. The new species has disporous plasmodium that varies in size and shape, with ellipsoidal mature spores in the sutural view that have a curved suture line. The spores are 12.6 (12.0-13.4) µm in length and 7.3 (6.7-8.0) µm in width. The two polar capsules present in the spore are pyriform and of equal size, with subterminal openings that project in opposite directions. The polar capsules are 3.5 (3.4-4.0) µm long and 2.6 (2.5-3.2) µm wide. Based on the partial sequences of the SSU rRNA gene of the Ellipsomyxa arariensis n. sp. spores found in Pygocentrus nattereri Kner, 1858 (1325 bps) and Pimelodus ornatus Kner, 1858 (1240 bps), the new species is clearly distinct from all the other myxozoan sequences deposited in GenBank. Based on Bayesian inference and p distances, the new species belongs to the "Ellipsomyxa clade", together with all the other Ellipsomxa species, reinforcing the monophyletic status of this genus. Overall, the morphological data and the partial sequences of the SSU rRNA gene provide a conclusive diagnosis of Ellipsomyxa arariensis n. sp. as a species distinct from all the other Ellipsomyxa species described previously.

Utrastructure and molecular phylogeny of the myxozoan Kudoa ocellatus n. sp. (Myxozoa: Kudoidae), a parasite of the Oscar, Astronotus ocellatus (Agassiz, 1831; Teleostei: Cichlidae), a fish from northern Brazil.

Kudoa ocellatus n. sp. was found in the musculature of Astronotus ocelattus (Agassiz, 1831) from the Arari River on Marajó Island in Pará, Brazil. The new species forms pseudocysts in the epaxial and hypaxial musculature composed of various spores that are pseudoquadrate in the apical view. In the lateral view, the spores were triangular or pyramidal. In the lateral view, the spores were 46 ± 0.11 µm (4.5-4.8) in length and 6.6 ± 0.3 µm (6.2-7.2) in width, with four pyriform polar capsules of equal size that measured 2.0 ± 0.16 µm (1.8-2.2) in length and 1.5 ± 0.18 µm (1.3-1.8) in width. Based on the partial (1418 bps) sequence of the SSU rDNA gene, Kudoa ocellatus n. sp. was distinct from all the other Kudoa species deposited in GenBank. The phylogenetic Bayesian Inference and P distance placed the new species together with the other Kudoa species that parasitize freshwater Amazonian fish. The morphological evidence, together with the SSU rDNA gene sequence, supported the description of Kudoa ocellatus n. sp., a distinct new species of the genus, which parasitizes a freshwater Amazonian cichlid.

Myxozoan infection in the muscle layer of the intestine of Rhamdia quelen from the Amazon River Basin, Brazil / Infecção por Myxozoa na camada muscular intestinal do Rhamdia quelen da Bacia do Rio Amazonas, Brasil

The present study investigated the morphology and pathology associated with the occurrence of cysts caused by Myxobolus sp. in the intestine of the silver catfish Rhamdia quelen . Comparisons with the other Myxobolus species that infect the intestines of cyprinids and siluriforms revealed that the pyriform spores of Myxobolus sp. are similar in shape to those described previously in M. miyairii, M. duodenalis and M. cunhai, but different in size. Morphometric analyses revealed that mature spores of Myxobolus sp. (10.9 x 5.1m) are smaller than those of most species except M. cunhai (10.0 x 5.0m), which has been described infecting the Brazilian catfish Pimelodus clarias , although the spores differ morphologically in relation to the shape of the polar capsules. Further research is necessary in order to clarify the taxonomic and phylogenetic relationships among these congeneric species.(AU)

O presente estudo investigou a morfologia e patologia associada com a ocorrência de cistos de Myxobolus sp. no intestino do peixe siluriforme Rhamdia quelen . Comparações com outras espécies de Myxobolus que têm infectado intestinos de carpas e bagres de água doce demonstraram que os esporos piriformes de Myxobolus sp. são similares no formato dos anteriormente descritos para M. miyairii, M. duodenalis e M. cunhai , diferindo, no entanto, quanto ao tamanho. As análises morfométricas revelaram que os esporos maduros de Myxobolus sp. (10,9 x 5,1m) são menores do que os da maioria das espécies, exceto para M. cunhai (10,0 x 5,0m), que foi descrito infectando o bagre brasileiro Clarias pimelodus , embora os esporos sejam diferentes morfologicamente em relação à forma das cápsulas polares. Futuras pesquisas são necessárias para esclarecer as relações taxonômicas e filogenéticas entre espécies congêneres.(AU)

Myxozoan infection in the muscle layer of the intestine of Rhamdia quelen from the Amazon River Basin, Brazil / Infecção por Myxozoa na camada muscular intestinal do Rhamdia quelen da Bacia do Rio Amazonas, Brasil

ABSTRACT: The present study investigated the morphology and pathology associated with the occurrence of cysts caused by Myxobolus sp. in the intestine of the silver catfish Rhamdia quelen . Comparisons with the other Myxobolus species that infect the intestines of cyprinids and siluriforms revealed that the pyriform spores of Myxobolus sp. are similar in shape to those described previously in M. miyairii, M. duodenalis and M. cunhai, but different in size. Morphometric analyses revealed that mature spores of Myxobolus sp. (10.9 x 5.1μm) are smaller than those of most species except M. cunhai (10.0 x 5.0μm), which has been described infecting the Brazilian catfish Pimelodus clarias , although the spores differ morphologically in relation to the shape of the polar capsules. Further research is necessary in order to clarify the taxonomic and phylogenetic relationships among these congeneric species.

RESUMO: O presente estudo investigou a morfologia e patologia associada com a ocorrência de cistos de Myxobolus sp. no intestino do peixe siluriforme Rhamdia quelen . Comparações com outras espécies de Myxobolus que têm infectado intestinos de carpas e bagres de água doce demonstraram que os esporos piriformes de Myxobolus sp. são similares no formato dos anteriormente descritos para M. miyairii, M. duodenalis e M. cunhai , diferindo, no entanto, quanto ao tamanho. As análises morfométricas revelaram que os esporos maduros de Myxobolus sp. (10,9 x 5,1μm) são menores do que os da maioria das espécies, exceto para M. cunhai (10,0 x 5,0μm), que foi descrito infectando o bagre brasileiro Clarias pimelodus , embora os esporos sejam diferentes morfologicamente em relação à forma das cápsulas polares. Futuras pesquisas são necessárias para esclarecer as relações taxonômicas e filogenéticas entre espécies congêneres.