The Oxymonads (or Oxymonadida) are a group of

flagellate A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and the ...

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

s found exclusively in the intestines of animals, mostly

termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

s and other wood-eating

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s. Along with the similar

parabasalid The parabasalids are a group of flagellated protists within the supergroup Excavata. Most of these eukaryotic organisms form a symbiosis, symbiotic relationship in animals. These include a variety of forms found in the intestines of termites and ...

flagellates, they harbor the

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

that are responsible for breaking down

cellulose Cellulose is an organic compound with the chemical formula, formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of glycosidic bond, β(1→4) linked glucose, D-glucose units. Cellulose is an important s ...

. There is no evidence for presence of

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

(not even anaerobic mitochondrion-like organelles like

hydrogenosome A hydrogenosome is a membrane-enclosed organelle found in some Anaerobic organism, anaerobic Ciliate, ciliates, Flagellate, flagellates, Fungus, fungi, and three species of Loricifera, loriciferans. Hydrogenosomes are highly variable organelles t ...

s or

mitosome A mitosome (also called a ''crypton'' in early literature) is a mitochondrion-related organelle (MRO) found in a variety of parasitic unicellular eukaryotes, such as members of the supergroup Excavata. The mitosome was first discovered in 1999 in ...

s) in oxymonads and three species have been shown to completely lack any molecular markers of mitochondria. It includes e.g. '' Dinenympha'', '' Pyrsonympha'', '' Oxymonas'', '' Streblomastix'', ''

Monocercomonoides ''Monocercomonoides'' is a genus of flagellate Excavata belonging to the order Oxymonadida. It was established by Bernard V. Travis and was first described as those with "polymastiginid flagellates having three anterior Flagellum, flagella and ...

'', and '' Blattamonas''.

Characteristics

Most Oxymonads are around 50 μm in size and have a single nucleus, associated with four

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

. Their

basal bodies A basal body (synonymous with basal granule, kinetosome, and in older cytological literature with blepharoplast) is a protein structure found at the base of a eukaryotic undulipodium (cilium or flagellum). The basal body was named by Theodor ...

give rise to several long sheets of

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...

s, which form an organelle called an axostyle, but different in structure from the axostyles of

s. The cell may use the axostyle to swim, as the sheets slide past one another and cause it to undulate. An associated fiber called the preaxostyle separates the flagella into two pairs. A few oxymonads have multiple nuclei, flagella, and axostyles. 2023 Oxymonad

Relationship to ''Trimastix'' and ''Paratrimastix''

The free-living flagellates '' Trimastix'' and '' Paratrimastix'' are closely related to the oxymonads. They lack aerobic

and have four flagella separated by a preaxostyle, but unlike the oxymonads have a feeding groove. This character places the Oxymonads, ''Trimastix'', and ''Paratrimastix'' among the Excavata, and in particular they may belong to the metamonads.

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies indeed place Preaxostyla (oxymonads, '' Trimastix'', and '' Paratrimastix'') in Metamonada.

Taxonomy

* Order Oxymonadida Grassé 1952 emend.

Cavalier-Smith Thomas (Tom) Cavalier-Smith, Royal Society, FRS, Royal Society of Canada, FRSC, Natural Environment Research Council, NERC Professorial Fellow (21 October 1942 – 19 March 2021), was a professor of evolutionary biology in the Departme ...

2003 ** Family Oxymonadidae Kirby 1928 xymonadaceae; Oxymonadinae Cleveland 1934*** Genus ?'' Metasaccinobaculus'' Freitas 1945 *** Genus '' Barroella'' Zeliff 1944 'Kirbyella'' Zeliff 1930 non Kirkaldy 1906 non Bolivar 1909*** Genus '' Microrhopalodina'' Grassé & Foa 1911 Kofoid & Olive Swezy">Swezy 1926">Charles_Atwood_.html" ;"title="Charles_Atwood_Kofoid.html" ;"title="'Proboscidiella'' Charles Atwood Kofoid">Kofoid & Olive Swezy">Swezy 1926*** Genus ''Opisthomitus'' Grassé 1952 non Duboscq & Grassé 1934 *** Genus '' Oxymonas'' Janicki 1915 *** Genus '' Sauromonas'' Grassé & Hollande 1952 ** Family Polymastigidae Bütschli 1884 olymastiginae Kirby 1931; Polymastigaceae; Streblomastigaceae; Streblomastigidae Kofoid & Swezy 1919*** Genus ?'' Paranotila'' Cleveland 1966 *** Genus ?'' Tubulimonoides'' Krishnamurthy & Sultana 1976 *** Genus '' Blattamonas'' Treitli et al. 2018 *** Genus ''Brachymonas'' (Grassé 1952) Treitli et al. 2018 non Hiraishi et al. 1995 *** Genus ''

'' Travis 1932 *** Genus '' Polymastix'' Bütschli 1884 non Gruber 1884 *** Genus '' Streblomastix'' Kofoid & Swezy 1920 ** Family Pyrsonymphidae Grassé 1892 yrsonymphaceae; Pyrsonymphinae Kirby 1937 nom. nud.; Dinenymphidae Grassé 1911; Dinenymphinae Cleveland et al. 1934; Dinenymphaceae*** Genus '' Dinenympha'' Leidy 1877 'Pyrsonympha'' (''Dinenympha'') (Leidy 1877) Koidzumi 1921*** Genus '' Pyrsonympha'' Leidy 1877 'Pyrsonema'' Kent 1881; ''Lophophora'' Comes 1910 non Coulter 1894 non Kraatz 1895 non Moeschler 1890** Family Saccinobaculidae Brugerolle & Lee 2002 ex Cavalier-Smith 2012 accinobaculinae Cleveland et al. 1934*** Genus '' Notila'' Cleveland 1950 *** Genus '' Saccinobaculus'' Cleveland-Hall & Sanders & Collier 1934

References

{{Taxonbar, from=Q618894 Flagellates Metamonads Anaerobes