Postgaardia

Postgaardia is a proposed basal clade of flagellate Euglenozoa, following Thomas Cavalier-Smith. As of April 2023, the Interim Register of Marine and Nonmarine Genera treats the group as a subphylum. A 2021 review of Euglenozoa places Cavalier-Smith's proposed members of Postgaardia in the class Symbiontida. As Euglenozoans may be basal eukaryotes, the Postgaardia may be key to studying the evolution of Eukaryotes, including the incorporation of eukaryotic traits such as the incorporation of alphaproteobacterial mitochondrial endosymbionts.

Euglenozoa are a large group of flagellate Discoba. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. Euglenozoa are represented by three major clades, i.e., Kinetoplastea, Diplonemea and Symbiontida. Euglenozoa are unicellular, mostly around 15–40 μm (0.00059–0.00157 in) in size, although some euglenids get up to 500 μm (0.020 in) long.