The Apicomplexa are a large phylum of mainly parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. The organelle is an adaptation that the apicomplexan applies in penetration of 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.
The gregarines are a group of Apicomplexan alveolates, classified as the Gregarinasina or Gregarinia. The large parasites inhabit the intestines of many invertebrates. They are not found in any vertebrates. Gregarines are closely related to both Toxoplasma and Plasmodium, which cause toxoplasmosis and malaria, respectively. Both protists use protein complexes similar to those that are formed by the gregarines for gliding motility and for invading target cells. This makes the gregarines excellent models for studying gliding motility, with the goal of developing treatment options for both toxoplasmosis and malaria. Thousands of different species of gregarine are expected to be found in insects, and 99% of these gregarine species still need to be described. Each insect species can be the host of multiple gregarine species. One of the most-studied gregarines is Gregarina garnhami. In general, gregarines are regarded as a very successful group of parasites, as their hosts are distributed over the entire planet.
Leucocytozoon is a genus of parasitic alveolates belonging to the phylum Apicomplexa.
Conoidasida is a class of parasitic alveolates in the phylum Apicomplexa. The class was defined in 1988 by Levine and contains two subclasses – the coccidia and the gregarines. All members of this class have a complete, hollow, truncated conoid. Gregarines tend to parasitize invertebrates with the mature gamonts being extracellular; the coccidia mostly infect vertebrates and have intracellular gamonts.
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.
Acroeimeria is a genus of parasites that contains those species which initially develop immediately beneath the brush-border of the intestinal epithelium, but the meronts and gamonts of which are early on extruded to form a layer on the surface of the gut mucosa. Morphologically they are similar to the Eimeria to which they are closely related. The genus was described in 1989 by Paperna and Landsberg.
The genus Schellackia comprises obligate unicellular eukaryotic parasites within the phylum Apicomplexa, and infects numerous species of lizards and amphibians worldwide. Schellackia is transmitted via insect vectors, primarily mites and mosquitoes, which take up the parasite in blood meals. These vectors then subsequently infect reptilian and amphibian which consume the infected insects. The parasites deform erythrocytes of the host into crescents, and can be visualised using a blood smear.
Aggregata is a genus of parasitic alveolates belonging to the phylum Apicomplexa.
Frenkelia is a genus of parasites in the phylum Apicomplexa. The species in this genus infect the gastrointestinal tracts of birds of prey and the tissues of small rodents.
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.
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.
A mucron is an attachment organelle found in archigregarines - an order of epicellular parasitic Conoidasida.
Mattesia is a genus of parasitic alveolates of the phylum Apicomplexa. Species in this genus infect insects.
The Platyproteum are a genus of parasitic alveolates in the phylum Apicomplexa. Species in this genus infect marine invertebrates.
Aseptatorina is a suborder of parasitic alveolates of the phylum Apicomplexia
Stylocephaloidea is a superfamily of parasites of the phylum Apicomplexia.
Nematopsis (Nee-mah-top-cis) is a genus gregarine Apicomplexan of the family Porosporidae. It is an aquatic parasite of crustaceans with a molluscan intermediate host. Nematopsis has been distinguished from the similar genus Porospora by its resistant and encapsulated oocyst. Little molecular biology has been performed on the members of the Nemaptosis and species are described based on molluscan and crustacean hosts as well as oocyst structure. A total of 38 species have been described and are found all over the world.
Gregarina garnhami is a eukaryotic unicellular organism belonging to the Apicomplexa described in 1956 by Canning as a parasite found in several locusts, such as the desert locust, African migratory locust, and Egyptian locust. Especially, the desert locust is the host for this species, as up to 100% of animals can become infected. An estimated thousands of different species of gregarines can be in insects and 99% of these gregarines still need to be described. Each insect is said to host multiple species. A remarkable feature of G. garnhami is its autofluorescence.
