Preaxostyla is a group of anaerobic/microaerophilic protozoa, uniting two subgroups: the oxymonads, which are commensals or symbionts of animals, and the free-living taxon Trimastix.
Keeling, Patrick, Kevin Carpenter, Vladimir Hampl, and Alastair Simpson.2009. Preaxostyla. Version 26 October 2009 (under construction).http://dev.tolweb.org/Preaxostyla/124889/2009.10.26 in The Tree of Life Web Project, http://tolweb.org/