Phylogeny of Trypanosomatidae and Bodonidae (Kinetoplastida) based on 18S rRNA: evidence for paraphyly of Trypanosoma and six other genera.

Phylogenetic analysis of 18S rRNA sequences from the families Trypanosomatidae and Bodonidae (Eugelenozoa: Kinetoplastida) was conducted using a variety of methods. Unlike previous analyses using unrooted trees and/or smaller numbers of sequences, the analysis did not support monophyly of the genus Trypanosoma, which includes the major human parasites T. cruzi (cause of Chagas' disease) and T. brucei (cause of African sleeping sickness). The section Salivaria of the genus Trypanosoma fell outside a cluster that includes the section Stercoraria of the genus Trypanosoma, along with members of the genera Leishmania, Endotrypanum, Leptomonas, Herpetomonas, Phytomonas, Crithidia, and Blastocrithidia. The phylogenetic analysis also indicated that the genera Bodo, Cryptobia, Leptomonas, Herpetomonas, Crithidia, and Blastocrithidia are polyphyletic. The results suggested that parasitism of vertebrates has probably arisen independently a number of times within the Trypanosomatidae.