Folia Parasitologica 62[1] 14 (2015) | DOI: 10.14411/fp.2015.014

Host-parasite and phylogenetic relationships of Myxobolus filamentum sp. n. (Myxozoa: Myxosporea), a parasite of Brycon orthotaenia (Characiformes: Bryconidae) in Brazil

Juliana Naldoni¹, Suellen A. Zatti¹, Kassia R.H. Capodifoglio², Tiago Milanin¹, Antônio A.M. Maia², Marcia R.M. Silva², Edson A. Adriano^1,3

¹ Animal Biology Department, Institute of Biology, University of Campinas, São Paulo, Brazil;

² Veterinary Medicine Department, College of Animal Science and Food Engineering, São Paulo University, São Paulo, Brazil;

³ Biology Science Department, Federal University of São Paulo, São Paulo, Brazil

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.

Keywords: taxonomy, 18S rRNA, ultrastructure, granulocytic cells, freshwater fish, Neotropical Region

Received: May 23, 2014; Accepted: October 13, 2014; Published online: February 9, 2015  Show citation