The Ascetosporea are a group of
eukaryote
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacte ...
s that are
parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
s of animals, especially marine
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
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
Cercozoa is a phylum of diverse single-celled eukaryotes. They lack shared morphological characteristics at the microscopic level, and are instead defined by molecular phylogenies of rRNA and actin or polyubiquitin. They were the first major eu ...
. Both produce
spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s without the complex structures found in similar groups (such as polar filaments or tubules).
Haplosporid spores have a single
nucleus
Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to:
*Atomic nucleus, the very dense central region of an atom
*Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA
Nucle ...
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 the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...
or
annelid
The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...
, although some infect other groups or freshwater species. The trophic cell is generally
multinucleate
Multinucleate cells (also known as multinucleated or polynuclear cells) are eukaryotic cells that have more than one nucleus per cell, i.e., multiple nuclei share one common cytoplasm. Mitosis in multinucleate cells can occur either in a coordinat ...
d. 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
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
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
The Ascetosporea are a group of eukaryotes that are parasites of animals, especially marine invertebrates. The two groups, the haplosporids and paramyxids, are not particularly similar morphologically, but consistently group together on molecula ...
Cavalier-Smith 2003
** Family
Claustrosporidiidae Larsson 1987
*** Genus ''
Claustrosporidium''
Larsson 1987
* Order
Paradiniida
The Ascetosporea are a group of eukaryotes that are parasites of animals, especially marine invertebrates. The two groups, the haplosporids and paramyxids, are not particularly similar morphologically, but consistently group together on molecula ...
Cavalier-Smith 2009
** Family
Paradiniidae Schiller 1935
*** Genus ''
Paradinium''
Chatton, 1910
* Order
Mikrocytida
The Ascetosporea are a group of eukaryotes that are parasites of animals, especially marine invertebrates. The two groups, the haplosporids and paramyxids, are not particularly similar morphologically, but consistently group together on molecula ...
Hartikainen et al. 2014
** Family
Mikrocytidae Hartikainen et al. 2014
*** Genus ''
Paramikrocytos''
Hartikainen et al. 2014
*** Genus ''
Microcytos''
Farley, Wolf & Elston 1988
* Order
Paramyxida
The Ascetosporea are a group of eukaryotes that are parasites of animals, especially marine invertebrates. The two groups, the haplosporids and paramyxids, are not particularly similar morphologically, but consistently group together on molecula ...
Chatton 1911 Chatton 1911; Paramyxidea Chatton 1911; Paramyxa">aramyxea Chatton 1911; Paramyxidea Chatton 1911; Paramyxa** Family
Marteiliidae Grizel et al. 1974 Desportes & Ginsburger-Vogel, 1977; Marteiliidea Desportes & Ginsburger-Vogel, 1977">cclusosporida; Marteiliida Desportes & Ginsburger-Vogel, 1977; Marteiliidea Desportes & Ginsburger-Vogel, 1977*** Genus ''
Paramarteilia''
Ginsburger-Vogel & Desportes 1979
*** Genus ''
Marteilia
''Marteilia'' is a protozoan genus of organisms that are parasites of bivalves. It causes QX disease in Sydney rock oysters and Aber disease in European flat oysters. After being infected by ''Marteilia'', bivalves lose pigmentation in their v ...
''
Grizel et al. 1974
** Family
Paramyxidae Chatton 1911
*** Genus ''
Paramyxa''
Chatton 1911
* Order
Haplosporida
The Ascetosporea are a group of eukaryotes that are parasites of animals, especially marine invertebrates. The two groups, the haplosporids and paramyxids, are not particularly similar morphologically, but consistently group together on molecula ...
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.html" ;"title="Coelosporidium.html" ;"title="'Coelosporidium">'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)
See also
*''
Haplosporidium nelsoni
''Haplosporidium nelsoni'' is a pathogen of oysters that originally caused oyster populations to experience high mortality rates in the 1950s, and still is quite prevalent today. The disease caused by ''H. nelsoni'' is also known as MSX (multinuc ...
''
References
Endomyxa
Parasitic rhizaria
Cercozoa classes
{{Parasitic SAR-stub