Application of the techniques of transmission electron microscopy and histology for analysis of myxozoans parasites of fish from Batalha river, middle Tietê river, São Paulo, Brazil

Myxozoans are metazoan parasites mainly on fish, with some of the most important pathogens of these hosts. There are about 2,200 described species for Myxosporea class, but in Brazil the studies are still scarce. In this study fish of different species were collected between March 2014 and August 2015 to be verified the presence of myxozoans parasites. The genera of myxozoans found were Henneguya and Myxobolus parasitizing fish of Characiformes and Siluriformes orders. The parasites collected were processed aiming a morphological analysis by light microscopy, histopathology and ultrastructural analysis, observing the host-parasite relationship. Henneguya sp. 1 was found parasitizing the gills of Astyanax altiparanae and Henneguya sp. 2 parasitizing the gills of Leporinus friderici. Myxobolus lomi (Myxobolus prochilodus), Henneguya sp. 3 and Myxobolus sp. 1 were found parasitizing the gills of Prochilodus lineatus causing deformities in fish primary lamellae. Henneguya sp. 4 was found parasitizing the gills of Cyphocharax Modestus, causing a junction of secondary lamellae and decreasing the useful breathing area of the fish. The ultrastructural analysis allowed the understanding of parasite-host interface. Also were observed Henneguya guanduensis parasitizing the intestine of Hoplosternum litoralle and Myxobolus sp. 2 parasitizing the intestine of Rhamdia quelen. Myxobolus aureus was found parasitizing the gonads and liver of Salminus hilarii. Histopathological analysis indicated the infertility of the affected oocytes. Morphological measures of parasites found were compared with those reported in the literature and did not found species that were similar in size. It was concluded that these are new species with the necessity of molecular analysis to confirm the study. (AU)