Morphological and molecular procedures were used to describe a new species of microsporidian that infects the muscles of the sub-opercular region and the caudal fins of the freshwater Aequidens plagiozonatus in Brazil. This microsporidian forms whitish xenomas containing variable number of spores, reaching up to ~0.4 mm in diameter. The mature spores, pyriformin shape, with slightly round ends, measured 3.4 ± 0.5 μm long and 1.9 ± 0.3 μm wide (n = 50) and showed characteristics typical of Microsporidia. The average thickness of the spore wall was 100 (96–108) nm (n = 50), and the spore wall was composed of two layers, a thin, electron-dense exospore and a thick electron-transparent endospore. The exospore was surrounded by a thin, irregular layer of granular material. The anchoring disc was mushroom-like, located in the apical region of the spore in an eccentric position relative to the spore axis, rendering bilateral asymmetry to the spore. The anterior part of the polar filament (PF) (manubrium) measured approximately 125 (122–128) nm thick (n = 30), and the angle of tilt between the anterior PF and the spore axis was ~45°; the posterior part was packed in 8–9 coils. Phylogenetic analysis showed a strongly supported clade containing family Spragueidae Weissenberg, 1976, family Tetramicridae Matthews and Matthews, 1980, Microsporidium sp. RBS1, and Kabatana spp. In conclusion, the available morphological, ultrastructural, and molecular data shows that this microsporidian is a new species belonging to group 4, classified as Potaspora aequidens n. sp. This is the second species described in the genus Potaspora.
Amazonian fish Parasite Microsporidia Ultrastructure Phylogeny
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We are grateful to The Edilson Matos Research Laboratory (LPEM–UFPA), “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” (CAPES), “Conselho Nacional de Desenvolvimento Científico e Tecnológico” (CNPq, Universal Research Program), Special Visitant Researcher-CAPES (88881.064967/2014-01), and “Fundação Amazônia Paraense de Amparo à Pesquisa” (FAPESPA) (Brazil). This study was partially supported by Eng. António de Almeida Foundation (Porto, Portugal); FCT (Lisbon, Portugal), within the scope of the PhD fellowship grant SFRH/BD/92661/2013 to S.R. and King Saud University (Riyadh, Saudi Arabia), within the scope of Project no. RGP-002. This work complies with the current laws of the countries in which it was performed.
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