A new Myxobolus (Cnidaria: Myxosporea) infecting the ornamental catfish Corydoras schwartzi from the Purus River in Brazil

Abstract

A new microscopic cnidarian is described, infecting five of thirty (16.6%) specimens of Corydoras schwartzi caught in the Purus River, State of Amazonas, Brazil. Histological analysis showed that cyst development occurred in the serosa layer of the intestine. Mature myxospores are ovoid in body shape in frontal view, 22.4 ± 0.3 μm in total length and 16.3 ± 0.1 μm in width. Internally, two aubergine-shaped, elongate symmetrical polar capsules occupy more than half the length of the spore, 14.3 ± 0.2 μm in length and 6.5 ± 0.1 μm in width. Ultrastructural analysis provided evidence of five polar filament coils inside the polar capsule and binucleated sporoplasm containing a moderate number of sporoplasmosomes. The valvogenic cells abutting each other form a sutural ridge and frequently a thin layer of homogeneous material separates the cells. The outer surface of the myxospore valves is smooth, with no evidence of formation of ridges in the valves. Immature myxospores in various stages of development were observed. This study is the first report of a myxosporean parasitizing C. schwartzi and the first report of a myxosporean infection in the intestine of an ornamental fish from South America.

Molecular diagnostic based on 18S rDNA and supplemental taxonomic data of the cnidarian coelozoic Ceratomyxa (Cnidaria, Myxosporea) and comments on the intraspecific morphological variation

“…For transmission electron microscopy, infected gall bladders were fixed for two days in 2.5% glutaraldehyde, diluted in 0.1 M sodium cacodylate buffer (pH 7.4), washed in a glucose-saline solution for 2 h and post-fixed in 2% osmium tetroxide (OsO 4 ) for 4 to 5 h. After dehydration in an ascending concentration series of ethanol, the samples were embedded in EMbed 812 resin (Electron Microscopy Sciences, Hatfield, PA, USA) (Mathews et al 2020c). Ultra-thin sections, double stained with uranyl acetate and lead citrate, were examined under a LEO 906 electron microscope operating at 60 kV in the Center for Electronic Microscopy (CEME) at the Federal University of São Paulo.…”

Morphostructural data and phylogenetic relationships of a new cnidarian myxosporean infecting spleen of an economic and ecological important bryconid fish from Brazil

“…All procedures were performed at 4 °C. After dehydration in an ascending ethanol series, the samples were embedded in EMbed 812 resin (Electron Microscopy Sciences, Hatfield, PA, USA) [18]. Ultrathin sections were double stained with uranyl acetate and lead citrate and examined in a LEO 906 electron microscope operated at 60 kV in the Institute of Biology at University of Campinas, Brazil.…”

Identificação e filogenia de novas espécies de mixozoários (Cnidaria: Myxozoa) parasitas de peixes ornamentais de ambientes naturais brasileiros

“…No Brasil, o conhecimento da diversidade de mixozoários ainda é muito escasso, como para a maioria dos grupos de parasitas em geral, bem como os possíveis danos que podem causar em seus hospedeiros, tendo em vista que o país abriga a mais rica e diversificada ictiofauna de água doce e marinha do planeta (Malabarba et al 1998;Buckup, Menezes e Ghazzi, 2007;Reis et al 2016).…”