Increasing the known biodiversity of cnidarian parasites of bryconid fishes from South America: two novelMyxobolusspecies with ultrastructure and ssrDNA-based phylogeny

This study increases the known biodiversity of cnidarian parasites in neotropical bryconid fishes. Two novelMyxobolusspecies are described based on morphology, ultrastructure and small subunit ribosomal DNA (ssrDNA) sequencing:Myxobolus vetuschicanusn. sp. infecting fins ofSalminus franciscanusandMyxobolus mineirusn. sp. infecting the mesentery ofBrycon orthotaeniafrom the Sao Francisco River basin, Minas Gerais State, Brazil. Ultrastructural analysis of the two species revealed an asynchronous sporogenesis process, with germinative cells and young developmental stages of myxospores in the periphery of the plasmodia. InM.vetuschicanusn. sp., the plasmodia were surrounded by a layer of fibroblasts and inM.mineirusn. sp., the plasmodial membrane had direct contact with the host tissue. The phylogenetic analysis based on the ssrDNA ofHenneguya/Myxobolusspecies showed that the two novelMyxobolusspecies grouped in subclades together with other parasite species of bryconid fishes. (AU)