12-422: Aseptatorina Blastogregarinorina Septatorina 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
24-443: A transverse septum. The marine gregarines are the most poorly studied members of this order. The eugregarines have been classified into 27 families with ~244 genera, 14 of which have more than 25 species each. There are ~900 species of septate gregarines and ~400 of aseptate. A revision to the taxonomy of this group has been proposed. Instead of the division into aseptate and septate taxa five new superfamilies have been proposed on
36-449: A zygote — the only diploid stage in the life cycle. The zygote forms an oocyst and within the oocyst, the sporozoites develop. The oocysts leave the gametocyst either via the latter's rupture or via sporoducts. Aseptatorina Aikinetocystidae Allantocystidae Diplocystidae Enterocystidae Ganymedidae Lecudinidae Monocystidae Schaudinnellidae Selenidiidae Thiriotiidae Urosporidae Aseptatorina
48-576: Is a suborder of parasitic alveolates of the phylum Apicomplexa There are eleven families recognised in this suborder. There are ~400 species in these families. Five families — Allantocystidae , Diplocystidae , Enterocystidae , Ganymedidae and Schaudinnellidae — have only one genus. Aikinetocystidae has two genera. Two families in this suborder — Ganymedidae and Thiriotiidae — infect crustaceans . The taxonomy of this suborder may be in need of revision as it has been shown based on SSU 18S rDNA sequences that four families — Ganymedidae from
60-445: Is inscribed by 90-300 epicytic folds resulting in stiff cells that are capable of gliding motility. However, a revision of the morphology of eugregarines has been proposed: they possess only the epimerite and epicytic crests (unlike the genuine mucron and longitudinal folds of Archigregarinorida ). Intestinal eugregarines are separated into septate (mostly terrestrial) and aseptate (mostly marine) gregarines, depending on whether
72-600: The Aseptatorina and Cephalolobidae , Porosporidae and Uradiophoridae from the Septatorina appear to form a superfamily. The name Cephaloidophoroidea has been proposed for this superfamily This suborder was created by Chakravarty in 1960. The gamont of the species in this suborder have a single compartment. An epimerite or mucron is found in some species. Syzygy occurs. Aikinetocystidae Aikinetocystis Nellocystis The Aikinetocystidae are
84-411: The basis of 18s RNA studies. These are Actinocephaloidea , Stylocephaloidea s.str. (not in the sense of Clopton, 2009 ), Ancoroidea , Cephaloidophoroidea , Gregarinoidea and Lecudinoidea . These proposed superfamilies have yet to reach general approval. The trophozoites have lost the apical complex and instead possess a mucron (aseptate species) or an epimerite (septate species). The surface
96-408: The known gregarine species. These protozoa are common parasites of many invertebrates including insects and polychete worms. Eugregarinorida has three recognised suborders: Aseptatorina, Blastogregarinorina and Septatorina. The intestinal eugregarines are separated into septate — suborder Septatina — and aseptate — suborder Aseptatina — depending on whether the trophozoite is superficially divided by
108-409: The larger as the primite. These are usually the largest stage of the life cycle. The paired gamonts form a membrane around themselves (encystment) — a process known as syzygy. The resulting gametocyst is usually spherical in shape. Within the gametocyst the gamonts give rise to gametes which may be of similar size (isogametes) or different sizes (anisogametes). The gametes fuse in pairs and give rise to
120-564: The parasite to new host usually takes place by oral ingestion of oocysts in both aquatic and terrestrial environments. Transmission along with egg laying is also known. The life cycle is completed in one host ( monoxenous ) with the exception of the Porosporicae whose life cycles involve a mollusc and a crustacean . After the oocysts are ingested by a suitable host, the sporozoites are released. These are haploid and usually number 8 per oocyte but may be as many as 16 or as few as 4 depending on
132-406: The species. The sporozoite attaches to or penetrates the intestinal wall. In the latter case the sporozoite may remain within the intestinal wall or enter the body cavity. The sporozoites increase in size and develop into trophozoites. The trophozoites develop into gamonts which associate with each other. The gamonts may not be equal in size: in this case the smaller is referred to as the satellite and
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#1732875618671144-434: The trophozoite cell is superficially marked by a transverse septum. In the aseptate (or acephalate) species the cell is not divided. In the septate (or cephalate) species the body is divided into at least 2 parts: a posterior portion which contains the nucleus (the deutomerite) and an anterior portion (the protomerite), which forms the epimerite . In some species the deutomerite may be further subdivided. The transmission of
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