Novel diversity and distributions of myxozoans in amphibians from Ecuador with the description of a new species of Cystodiscus

Among parasites with vertebrate hosts, myxozoans (Cnidaria) remain some of the least studied both taxonomically and geographically. We conducted the first reported surveys for myxozoans from amphibian hosts in Ecuador at two localities: a mid-elevation cloud forest on the Chocó region (western slopes of the Andes) and a lowland Amazonian tropical forest, east of the Andes. We sampled 177 gall bladders and 17 kidneys across the surveys. We found no evidence of myxozoans in the cloud forest site. Myxozoans of the genus Cystodiscus were encountered in the gallbladders of multiple amphibian species from the Amazonian rainforest site, including new host records. Our molecular phylogenies show that, while many of these myxozoans were referable to a clade of C. cf. immersus, we also discovered a divergent lineage of Cystodiscus in the gall bladder of a host that, unlike other known amphibian hosts, has arboreal oviposition. We describe this lineage as a new species, Cystodiscus insperatus n. sp., and infer transmission scenarios consistent with the unique ecology of its frog host. We also report for the first time molecular evidence of a possible new lineage of Sphaerospora living in the kidneys of Osteocephalus taurinus (Anura). Collectively, our study highlights the potential for (i) large biogeographic barriers (like the Andes) to influence the distribution of myxozoans and (ii) intermediate host ecology to drive the evolution of novel lineages of these parasites.