Cryptic microsporidian parasites differentially affect invasive and native Artemia spp.

- Anostracaspora rigaudi was more virulent than Enterocytospora artemiae.
- Prevalence of An. rigaudi was four times higher in native than in invasive hosts.
- Prevalence of E. artemiae was three times lower in native than in invasive hosts.
- Native and invaded Artemia franciscana host populations did not differ in prevalence.
- No evidence was found of the co-introduction of E. artemiae with the invasive host.