Breviatea are a group of free-living, amitochondriate parasitic protists with uncertain phylogenetic position.[2][3] They are biflagellate, and can live in anaerobic (oxygen-free) environments.[4][5][6] They are currently placed in the proposed Obazoa clade.[7] They likely do not possess vinculin proteins.[8] Their metabolism relies on fermentative production of ATP as an adaptation to their low-oxygen environment.[2][3]
The lineage emerged roughly one billion years ago, at a time when the oxygen content of the Earth's oceans were low, and they thus developed anaerobic lifestyles.[4] Together with Apusomonads, they are the closest relatives of the Opisthokonts, a group that includes animals and fungi.[5][9]
Cladogram of Breviatidae[10]Breviata
Lenisia
Pygsuia
Subulatomonas
