The Apicomplexa are organisms of a large phylum of mainly parasitic alveolates. Most possess a unique form of organelle structure that comprises a type of (non-photosynthetic) plastid called an apicoplast—with an apical complex membrane. The organelle's apical shape is an adaptation that the apicomplexan applies in penetrating a host cell.
Plasmodium is a genus of unicellular eukaryotes that are obligate parasites of vertebrates and insects. The life cycles of Plasmodium species involve development in a blood-feeding insect host which then injects parasites into a vertebrate host during a blood meal. Parasites grow within a vertebrate body tissue before entering the bloodstream to infect red blood cells. The ensuing destruction of host red blood cells can result in malaria. During this infection, some parasites are picked up by a blood-feeding insect, continuing the life cycle.
Hepatozoon is a genus of Apicomplexa alveolates which incorporates over 300 species of obligate intraerythrocytic parasites. 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, the genus is more well known in veterinary circles for causing a tick-borne disease called hepatozoonosis in some mammals.
Megaloschizonts are large schizonts that produce extremely high numbers of merozoites. They are found in various species of the Phylum Apicomplexa. The Apicomplexa phylum contains several parasitic protozoans. They have a very complex life cycle that includes several stages. Megaloschizonts and the smaller schizonts are the part of the life cycle that takes place inside the infected host organism and operates as an asexually reproductive cell. Megaloschizonts appear as grey-white nodules found in the smooth muscle of major organs, such as the heart, liver, lung or spleen.
Adeleorina is a suborder of parasites in the phylum Apicomplexa.
Colpodella is a genus of alveolates comprising 5 species, and two further possible species: They share all the synapomorphies of apicomplexans, but are free-living, rather than parasitic. Many members of this genus were previously assigned to a different genus - Spiromonas.
Achromatorida is an order of non-pigmented intraerythrocytic parasitic alveolates belonging to the subclass Haemosporidiasina. The order was created by Jacques Euzéby in 1988.
Dactylosoma is a genus of parasitic alveolates of the phylum Apicomplexa.
Haemohormidium is a genus of parasitic alveolates in the phylum Apicomplexa. They have two hosts in their life cycle: the vertebrate hosts are fish and the invertebrate vectors are leeches.
Aggregata is a genus of parasitic alveolates belonging to the phylum Apicomplexa.
Hammondia is a genus of parasitic alveolates in the phylum Apicomplexa.
Klossiella is a genus of parasitic alveolates of the phylum Apicomplexa. Species in this genus infect the renal tract of mammals and intestinal tract of snakes.
The Archigregarinorida are an order of parasitic alveolates in the phylum Apicomplexa. Species in this order infect marine invertebrates — usually annelids, ascidians, hemichordates and sipunculids.
Hyaloklossia is a genus of parasitic alveolates in the phylum Apicomplexa. Only two species in this genus are currently recognised.
The Neogregarinorida are an order of parasitic alveolates in the phylum Apicomplexa. Species in this order infect insects and are usually found in the fat body, hemolymph, hypodermis, intestine or Malpighian tubules. The most common site of infection is the fat body: many species are pathogenic for their hosts.
Merocystis is a genus in the phylum Apicomplexa.
Pseudoklossia is a genus in the phylum Apicomplexa. Species in this genus infect marine molluscs, although one species infects in an ascidian worm. The life cycle is heteroxenous.
The Eugregarinorida are the most large and diverse order of gregarines — parasitic protists belonging to the phylum Apicomplexa. Eugregarines are found in marine, freshwater and terrestrial habitats. These species possess large trophozoites that are significantly different in morphology and behavior from the sporozoites. This taxon contains most of the known gregarine species.
Apicystis is a genus of parasitic alveolates of the phylum Apicomplexa.
Heydornia is a genus of parasitic alveolates in the phylum Apicomplexa.
