Cryptosporidium myocastoris n. sp. (Apicomplexa: Cryptosporidiidae), the Species Adapted to the Nutria ( Myocastor coypus )

spp., common parasites of vertebrates, remain poorly studied in wildlife. This study describes the novel species adapted to nutrias ( ). A total of 150 faecal samples of feral nutria were collected from locations in the Czech Republic and Slovakia and examined for spp. oocysts and specific DNA at the , actin, 70, and loci. Molecular analyses revealed the presence of ( = 1), subtype family XIId ( = 5) and n. sp. XXIIa ( = 2), and XXIIb ( = 3). Only nutrias positive for shed microscopically detectable oocysts, which measured 4.8-5.2 × 4.7-5.0 µm, and oocysts were infectious for experimentally infected nutrias with a prepatent period of 5-6 days, although not for mice, gerbils, or chickens. The infection was localised in jejunum and ileum without observable macroscopic changes. The microvilli adjacent to attached stages responded by elongating. Clinical signs were not observed in naturally or experimentally infected nutrias. Phylogenetic analyses at , actin, and 70 loci demonstrated that n. sp. is distinct from other valid species.