The Ascetosporea are a group of

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

s that are

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

s of animals, especially marine

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s. The two groups, the haplosporids and paramyxids, are not particularly similar morphologically, but consistently group together on molecular trees, which place them near the base of the Cercozoa. Both produce

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s without the complex structures found in similar groups (such as polar filaments or tubules). Haplosporid spores have a single nucleus and an opening at one end, covered with an internal diaphragm or a distinctive hinged lid. After emerging, it develops within the cells of its host, usually a marine

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

or annelid, although some infect other groups or freshwater species. The trophic cell is generally multinucleated. Paramyxids develop within the digestive system of marine invertebrates, and undergo internal budding to produce multicellular spores. A 2009 study concluded that ''Haplosporidium'' species form a paraphyletic group and that the taxonomy of the haplosporidians needs a thorough revision.

Taxonomy

Class Ascetosporea Desportes & Ginsburger-Vogel, 1977 emend. Cavalier-Smith 2009 * Genus ?'' Marteilioides'' Comps, Park & Desportes 1986 * Genus ?'' Oryctospora'' Purrini & Weiser 1991 * Order Claustrosporida Cavalier-Smith 2003 ** Family Claustrosporidiidae Larsson 1987 *** Genus '' Claustrosporidium'' Larsson 1987 * Order Paradiniida Cavalier-Smith 2009 ** Family Paradiniidae Schiller 1935 *** Genus '' Paradinium'' Chatton, 1910 * Order Mikrocytida Hartikainen et al. 2014 ** Family Mikrocytidae Hartikainen et al. 2014 *** Genus '' Paramikrocytos'' Hartikainen et al. 2014 *** Genus '' Microcytos'' Farley, Wolf & Elston 1988 * Order Paramyxida Chatton 1911 aramyxea Chatton 1911; Paramyxidea Chatton 1911; Paramyxa** Family Marteiliidae Grizel et al. 1974 cclusosporida; Marteiliida Desportes & Ginsburger-Vogel, 1977; Marteiliidea Desportes & Ginsburger-Vogel, 1977*** Genus '' Paramarteilia'' Ginsburger-Vogel & Desportes 1979 *** Genus '' Marteilia'' Grizel et al. 1974 ** Family Paramyxidae Chatton 1911 *** Genus '' Paramyxa'' Chatton 1911 * Order Haplosporida Caullery & Mesnil 1899 [Balanosporida Sprague, 1979; Haplosporidia Hall, 1953; Haplosporea Caullery 1953; Haplospora Margulis & Schwartz, 1998; Haplosporidiidea Poche, 1913; Haplosporidies Caullery and Mesnil, 1905] ** Genus ?''Bertramia'' Mesnil & Caullery 1897 non Weiser & McCauley 1974 ** Genus ?''Coleospora'' Gibbs 1959 ** Family Nephridiophagidae Sprague 1970 ephridiophagea*** Genus '' Nephridiophaga'' Woolever 1966 'Coelosporidium'' Mesnil & Marchoux 1897">Coelosporidium.html" ;"title="'Coelosporidium">'Coelosporidium'' Mesnil & Marchoux 1897** Family Urosporidiidae Sprague 1979 [Anurosporidiidae] *** Genus ''Urosporidium'' Caullery & Mesnil 1905 [''Anurosporidium'' Caullery & Chappelier 1906] (8 species) ** Family Haplosporidiidae Sprague 1979 *** Genus '' Bonamia'' Pichot et al. 1980 *** Genus '' Haplosporidium'' Caullery & Mesnil 1899 (23 species) *** Genus '' Minchinia'' (Lankester 1895) Labbe 1896 (5 species)

References

Endomyxa Parasitic rhizaria Rhizaria classes {{Parasitic SAR-stub