heydornia heydornia heydornia is a genus of parasitic alveolates in the phylum apicomplexa. heydornia scientific classification domain: eukaryota (unranked): sar (unranked): alveolata phylum: apicomplexa class: conoidasida subclass: coccidiasina order: eucoccidiorida suborder: eimeriorina family: sarcocystidae subfamily: toxoplasmatinae genus: heydornia species heydornia heydorni heydornia triffittae history this genus was created in 2016 by splitting canid-infecting species from hammondia based on the molecular phylogenetic analysis. life cycle the species in this genus have two vertebrate hosts in their life cycle: a canid (the definitive host) and prey species (the intermediate host). they are strictly heteroxenous.