Breviatea, commonly known as breviate amoebae,[3] are a group of free-living, amitochondriate protists with uncertain phylogenetic position.

[4] The lineage emerged roughly one billion years ago, at a time when the oxygen content of the Earth's oceans was low, and they thus developed anaerobic lifestyles.

In the cells of Pygsuia, for which the complete transcriptome is known, there is a single smooth MRO that lacks a mitochondrial genome and most components of the electron transport chain.

They are closely related to the apusomonads and the Opisthokonta supergroup, and together they compose the larger clade Obazoa, which is the sister group to Amoebozoa.

[4] CRuMs Amoebozoa Breviata anathema Subulatomonas tetraspora Lenisia limosa Pygsuia biforma Apusomonadida Holozoa Holomycota The class Breviatea was created in 2004 by British protozoologist Thomas Cavalier-Smith to group a problematic taxon previously known as ‘Mastigamoeba invertens’.