The findings in Giardia would support the idea that Excavata or more definitely Diplomonadida
, including this protist, would not be a primitive eukaryote but would also belong to the latter group corresponding to the bikonts.
Unique phylogenetic position of Diplomonadida
based on the complete small subunit ribosomal RNA sequence of Giardia ardeae, Giardia muris, Giardia duodenalis and Hexamita sp.
The Trichomonadida, Oxymonadida, Retortomonadida, and Diplomonadida
, for example, are all restricted to an enteral anaerobic environment and lack mitochondria (Levine et al.