The phylum Apicomplexa is characterized by the unique cell organisation of the zoites, the infective stages of unicellular parasites previously designated as Sporozoa. Apicomplexa includes Coccidian and Hematozoa well known for human and veterinary diseases they cause, such as malaria, toxoplasmosis, babesiosis, coccidiosis, and the large group of Gregarines, the early branching Apicomplexa. Gregarines are parasite of invertebrates and urochordates and they performed an extraordinary radiation from the marine and terrestrial hosts known from the Cambrian biodiversity explosion. After the...