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Monocermonoides melolanthae.jpg
Monocercomonoides melolanthae
Scientific classification

Grassé 1952 emend. Cavalier-Smith 2003
  • Oxymonadales
  • Polymastigales
  • Pyrsonymphales

The Oxymonads are a group of flagellated protozoa found exclusively in the intestines of termites and other wood-eating insects. Along with the similar parabasalid flagellates, they harbor the symbiotic bacteria that are responsible for breaking down cellulose.

It includes Dinenympha, Pyrsonympha, and Oxymonas.[1]


Most Oxymonads are around 50 μm in size and have a single nucleus, associated with four flagella. Their basal bodies give rise to several long sheets of microtubules, which form an organelle called an axostyle, but different in structure from the axostyles of parabasalids. 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.

Relationship to Trimastix[edit]

The free-living flagellate Trimastix is closely related to the oxymonads.[2] It lacks mitochondria and has four flagella separated by a preaxostyle, but unlike the oxymonads has a feeding groove. This character places the Oxymonads and Trimastix among the Excavata, and in particular they may belong to the metamonads.



  1. ^ Moriya S, Dacks JB, Takagi A, et al. (2003). "Molecular phylogeny of three oxymonad genera: Pyrsonympha, Dinenympha and Oxymonas". J. Eukaryot. Microbiol. 50 (3): 190–7. doi:10.1111/j.1550-7408.2003.tb00115.x. PMID 12836875.
  2. ^ Dacks JB, Silberman JD, Simpson AG, et al. (June 2001). "Oxymonads are closely related to the excavate taxon Trimastix". Mol. Biol. Evol. 18 (6): 1034–44. doi:10.1093/oxfordjournals.molbev.a003875. PMID 11371592.
  3. ^ "Part 1- Virae, Prokarya, Protists, Fungi". Collection of genus-group names in a systematic arrangement. Archived from the original on 14 August 2016. Retrieved 30 June 2016.