title: Host-parasite and phylogenetic relationships of Myxobolus filamentum sp. n. (Myxozoa: Myxosporea), a parasite of Brycon orthotaenia (Characiformes: Bryconidae) in Brazil.
abstract: Myxobolus filamentum sp. n. was found infecting gill filaments of three of 39 Brycon orthotaenia Günther specimens examined (8%), which were taken from the river São Francisco in Minas Gerais state, Brazil. Plasmodia of the parasite were white and long, measuring 5 mm in lenght. Mature spores of M. filamentum sp. n. were oval from the frontal view and biconvex from the lateral view, measuring 7.5-9.7 µm (9.0 ± 0.3 µm) in length and 5.2-7.3 µm (6.2 ± 0.4 µm) in width. The polar capsules were elongated and equal in size, measuring 3.8-5.5 µm (4.7 ± 0.3 µm) in length and 1.3-2.2 µm (1.7 ± 0.1 µm) in width. The development of the parasite led to compression of the adjacent tissues and inflammatory infiltrate with granulocytic cells. Ultrastructural observation revealed that the plasmodia were delimited by two membranes, which had numerous and extensive pinocytotic channels extending into the wide ectoplasm zone. The plasmodial wall exhibited abundant villi-like projections and a thin layer of granular material prevented direct contact between the plasmodial wall and the host tissue. Phylogenetic analysis, based on 18S rDNA, showed M. filamentum sp. n. as a sister species of Myxobolus oliveirai Milanin, Eiras, Arana, Maia, Alves, Silva, Carriero, Ceccarelli et Adriano, 2010, a parasite of other fish species of the genus Brycon Müller et Troschel from South America.
authors.affiliation: Animal Biology Department, Institute of Biology, University of Campinas, Sao Paulo, Brazil;
authors.forename: Juliana
authors.initials: J
authors.lastname: Naldoni
authors.affiliation: Animal Biology Department, Institute of Biology, University of Campinas, Sao Paulo, Brazil;
authors.forename: Suellen A
authors.initials: SA
authors.lastname: Zatti
authors.affiliation: Veterinary Medicine Department, College of Animal Science and Food Engineering, Sao Paulo University, Sao Paulo, Brazil;
authors.forename: Kassia R H
authors.initials: KR
authors.lastname: Capodifoglio
authors.affiliation: Animal Biology Department, Institute of Biology, University of Campinas, Sao Paulo, Brazil;
authors.forename: Tiago
authors.initials: T
authors.lastname: Milanin
authors.affiliation: Veterinary Medicine Department, College of Animal Science and Food Engineering, Sao Paulo University, Sao Paulo, Brazil;
authors.forename: Antonio A M
authors.initials: AA
authors.lastname: Maia
authors.affiliation: Veterinary Medicine Department, College of Animal Science and Food Engineering, Sao Paulo University, Sao Paulo, Brazil;
authors.forename: Marcia R M
authors.initials: MR
authors.lastname: Silva
authors.affiliation: Animal Biology Department, Institute of Biology, University of Campinas, Sao Paulo, Brazil.|Biology Science Department, Federal University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Edson A
authors.initials: EA
authors.lastname: Adriano
keywords: 18S rRNA; Neotropical Region; freshwater fish; granulocytic cells; taxonomy; ultrastructure