Species have been described from all groups of tetrapod vertebrates, as well as a wide range of haematophagous arthropods, which serve as both the vectors and definitive hosts of the parasite.

By far the most biodiverse and prevalent of all haemogregarines, the genus is distinguished by its unique reciprocal trophic lifecycle which lacks the salivary transmission between hosts commonly associated with other apicomplexans.

While particularly prevalent in amphibians and reptiles,[1] the genus is more well known in veterinary circles for causing a tick-borne disease called hepatozoonosis in some mammals.

The gamonts are large, conspicuous organisms which occupy a significant portion of the erythrocyte, and are easily visible on simple blood films.

This simplified lifecycle is, of course, insufficient for species which infect vertebrate and invertebrate hosts which do not directly feed on one another, necessitating an even more complex cycle.