Taxonomy and 18S rDNA-based phylogeny of Henneguya multiradiatus n. sp. (Cnidaria: Myxobolidae) a parasite of Brochis multiradiatus from Peruvian Amazon

Abstract A new myxozoan species belonging to the genus Henneguya was isolated from the serous membrane of the visceral cavity of the hognosed catfish Brochis multiradiatus from Peruvian Amazon. Whitish plasmodia, macroscopically visible, were found in four of the thirty examined fishes. Mature myxospores were ellipsoidal in shape in frontal view and had a total length of 44.5 ± 0.6 μm (43.9–45.1), spore body measured 18.7 ± 0.9 μm (16.8–19.6) in length, 7.1 ± 0.2 μm (6.6–7.4) in width and 5.5 ± 0.3 μm (4.9–5.6) in thickness. The two polar capsules were elongated and equal in size, measuring 9.1 ± 0.1 μm (8.8–9.4) in length and 1.7 ± 0.1 μm (1.6–1.8) in width, occupying half of the myxospore body. Polar tubules coiled in 10–11 turns perpendicular to the long axis of the polar capsule. The caudal appendage was not bifurcated and measured 25.8 ± 0.6 μm (24.7–26.5) in length. The sequencing of the 18S rDNA gene resulted in 1400 bp and this sequence did not match any of the myxozoans available in GenBank. Phylogenetic analysis placed the new species in a well-supported subclade of Henneguya spp. infecting callichthyid fishes, with Henneguya loretoensis being the closest species. This study is the first description of a myxozoan species, Henneguya multiradiatus n. sp. from a fish of the genus Brochis.