title: Infection of the heart of Pimelodus ornatus (Teleostei, Pimelodidae), by Myxobolus sp. (Myxozoa, Myxobolidae).
abstract: 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.
authors.affiliation: Laboratório de Pesquisa Carlos Azevedo, Universidade Federal Rural da Amazônia - UFRA, Belém, PA, Brasil.
authors.forename: Edilson
authors.initials: E
authors.lastname: Matos
authors.affiliation: Laboratório de Morfofisiologia e Sanidade Animal, Universidade do Estado do Amapá - UEAP, Macapá, AP, Brasil.
authors.forename: Marcela
authors.initials: M
authors.lastname: Videira
authors.affiliation: Laboratório de Pesquisa Carlos Azevedo, Universidade Federal Rural da Amazônia - UFRA, Belém, PA, Brasil.
authors.forename: Michele
authors.initials: M
authors.lastname: Velasco
authors.affiliation: Laboratório de Patologia Animal, Universidade do Oeste Paulista - UNOESTE, Presidente Prudente, SP, Brasil.
authors.forename: Osimar
authors.initials: O
authors.lastname: Sanches
authors.affiliation: Faculdade de Veterinária, Universidade Federal Fluminense - UFF, Niterói, RJ, Brasil.
authors.forename: Sergio Carmona de São
authors.initials: SC
authors.lastname: Clemente
authors.affiliation: Laboratório de Pesquisa Edilson Matos, Universidade Federal do Pará - UFPA, Belém, PA, Brasil.
authors.forename: Patricia
authors.initials: P
authors.lastname: Matos
mesh_terms: D000818:Animals; D002397:Catfishes / Q000469:parasitology*; D005393:Fish Diseases / Q000175:diagnosis / Q000469:parasitology*; D009205:Myocarditis / Q000175:diagnosis / Q000469:parasitology / Q000662:veterinary*; D055766:Myxobolus; D010273:Parasitic Diseases, Animal / Q000175:diagnosis