Before this date the species of this genus were confused with Toxoplasma gondii to which they are closely related.
[1] The canid-infecting species, H. heydorni and H. triffittae, have been split into new genus Heydornia based on the molecular phylogenetic analysis.
In the gastrointestinal tract of the definitive host the parasite undergoes sexual reproduction, forms a zygote which after some divisions forms a cyst that is excreted.
The cyst is subsequently ingested by the prey species in whom the parasite decysts and invades its tissues wherein it again multiplies and encysts.
After ingestion of the tissues of the prey species by the definitive host the parasite again decysts and multiplies.