flux and classification has changed throughout the years since it was formally named in 1970. By 1987, a comprehensive survey of the phylum was completed: in all, 4516 species and 339 genera had been named. They consisted of: Class Conoidasida Subclass Gregarinasina p.p. Order Eugregarinorida, with 1624 named species and 231 named genera Subclass Coccidiasina p.p Order Eucoccidiorida p.p Suborder Adeleorina p.p Group Hemogregarines, with 399 species and four genera Suborder Eimeriorina, with 1771 species and 43 genera Class Aconoidasida Order Haemospororida, with 444 species and nine genera Order Piroplasmorida, with 173 species and 20 genera Other minor groups omitted above, with 105 species and 32 genera Although considerable revision of this phylum has been done (the order Haemosporidia now has 17 genera rather than 9), these numbers are probably still approximately correct. Jacques Euzéby (1988) Jacques Euzéby in 1988 created a new class Haemosporidiasina by merging subclass Piroplasmasina and suborder Haemospororina. Subclass Gregarinasina (the gregarines) Subclass Coccidiasina Suborder Adeleorina (the adeleorins) Suborder Eimeriorina (the eimeriorins) Subclass Haemosporidiasina Order Achromatorida Order Chromatorida The division into Achromatorida and Chromatorida, although proposed on morphological grounds, may have a biological basis, as the ability to store haemozoin appears to have evolved only once. Roberts and Janovy (1996) Roberts and Janovy in 1996 divided the phylum into the following subclasses and suborders (omitting classes and orders): Subclass Gregarinasina (the gregarines) Subclass Coccidiasina Suborder Adeleorina (the adeleorins) Suborder Eimeriorina (the eimeriorins) Suborder Haemospororina (the haemospororins) Subclass Piroplasmasina (the piroplasms) These form the following five taxonomic groups: The gregarines are, in general, one-host parasites of invertebrates. The adeleorins are one-host parasites of invertebrates or vertebrates, or two-host parasites that alternately infect haematophagous (blood-feeding) invertebrates and the blood of vertebrates. The eimeriorins are a diverse group that includes one host species of invertebrates, two-host species of invertebrates, one-host species of vertebrates and two-host species of vertebrates. The eimeriorins are frequently called the coccidia. This term is often used to include the adeleorins. Haemospororins, often known as the malaria parasites, are two-host Apicomplexa that parasitize blood-feeding dipteran flies and the blood of various tetrapod vertebrates. Piroplasms where all the species included are two-host parasites infecting ticks and vertebrates. Perkins (2000) This scheme is taken from Perkins et al. It is outdated as the Perkinsidae have since been recognised as a sister group to the dinoflagellates rather that the Apicomplexia. The remainder of the scheme appears to be valid: