Anaeromonadea

Preaxostyla, also known as Anaeromonadea, is a group of excavate protists, comprising the oxymonads, Trimastix, and Paratrimastix. This group is studied as a model system for reductive evolution of mitochondria, because it includes both organisms with anaerobic mitochondrion-like organelles (Trimastix and Paratrimastix), and those that have completely lost their mitochondria (oxymonads Monocercomonoides, Streblomastix, and Blattamonas).

==Phylogeny and taxonomy== Based on the work of Zhang et al. 2015. {{clade| style=font-size:100%;line-height:80% |1={{Clade |1=Trimastix Kent 1880 {Trimastigida Cavalier-Smith 2003: Trimastigidae Saville Kent 1880} |2={{Clade |1=Paratrimastix Zhang et al. 2015 {Paratrimastigidae Zhang et al. 2015} |2=Oxymonadida Grassé 1952 emend. Cavalier-Smith 2003 }} }} }}