Oxymonadida

Article By:

Lackey, James B. Department of Environmental Engineering, University of Florida, Gainesville, Florida.

Last reviewed:January 2021

DOI:https://doi.org/10.1036/1097-8542.480900

An order of class Zoomastigophorea in the phylum Protozoa. These are colorless flagellate symbionts in the digestive tract of the roach Cryptocercus and of certain termites. They are xylophagous; that is, they ingest wood particles taken in by the host. Seven or more genera of medium or large size have been identified, with the organisms varying from pyriform to ovoid in shape. At the anterior end, a pliable necklike rostrum attaches the organism to the host intestinal wall, but the organisms are sometimes free (see illustration). They can be either uni- or multinucleate. These organisms are termed karyomastigonts and each gives rise to two pairs of flagella in the unattached cells, with two flagella to each blepharoplast. In the rostrum, there is an axostylar apparatus, fibrils which pass to, and emerge at the posterior part of, the body. The nuclei contain long threadlike persistent chromosomes which appear to pass at random onto an intranuclear spindle. Isogamous (union of similar gametes) sexual processes have been described for three genera. In some cases, at least, these parallel the molting of the host.

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