Archezoa was a
kingdom proposed by
eukaryotes that diverged before the origin of
mitochondria. At various times, the
metamonads, and the
Microsporidia were included here. These groups appear near the base of eukaryotic evolution on
rRNA trees. However, all these groups are now known to have developed from mitochondriate ancestors, and trees based on other genes do not support their basal placement. The kingdom Archezoa has therefore been abandoned.