Phylogenetic analyses show that free-living trichomonads do not form a clade and instead branch in several different positions within the context of their parasitic relatives. We sequenced the small subunit rDNA from three different strains of free-living trichomonads.
These data demonstrated that the free-living parabasalids P. keilini and Lacusteria cypriaca n. gen., n. sp., form a paraphyletic assemblage near the origin of a clade consisting mostly of parasitic trichomonadids.