Ellipsomyxa (Cnidaria: Myxozoa): diversity, life history, and description of new species from the Amazon Basin

Myxozoans belonging to the genus Ellipsomyxa have been described in the gallbladders of fish from marine, brackish, and freshwater environments worldwide. Recent research suggests substantial speciation in South America freshwater environments. This study enhances our understanding of the diversity of freshwater Ellipsomyxa in the Amazon Basin, with the description of two new species. It also provides novel life history insights, expands host ranges, and proposes taxonomic revision. Ellipsomyxa filiformis n. sp. was identified infecting the gallbladder of the pimelodid Amazonian fish Hypophthalmus marginatus. Ellipsomyxa granulosa n. sp. was found in the gallbladder of the curimatid Curimata inornata. Ellipsomyxa amazonensis is here reported to parasitise two pimelodids - Pinirampus pirinampu and Platynematichthys notatus. Ellipsomyxa paraensis is reported to parasitize the cichlid Satanoperca jurupari and the prochilodontid Prochilodus nigricans. Morphological and small subunit ribosomal DNA sequence data support the reclassification of Ellipsomyxa santarenensis as a junior synonym of E. paraensis. Molecular phylogenetic analyses indicate that E. filiformis n. sp. and E. granulosa n. sp. comprise a sister lineage to Ellipsomyxa papantla. Ultrastrucutural analyses of E. filiformis n. sp. and E. granulosa n. sp. revealed details of the plasmodia, including numerous filopodial and pseudopodial projections of the ectoplasm, and a concentration of actin associated with the cytoskeleton.