Phylogenetic position of the kinetoplastids, Cryptobia bullocki, Cryptobiacatostomi, and Cryptobia salmositica and monophyly of the genus Trypanosoma inferred from small subunit ribosomal RNA sequences

Phylogenetic relationships within the kinetoplastid flagellates were inferr ed from comparisons of small-subunit ribosomal RNA gene sequences. These in cluded three new gene sequences from Cryptobia bullocki, (2091 bp), Cryptob ia catostomi (2090 bp), and Cryptobia salmositica (2091 bp). Trees produced using maximum parsimony and distance-matrix methods (least squares and nei ghbor-joining) demonstrated with strong bootstrap support, that the kinetop lastids are a monophyletic group divided into two major lineages consistent with the two suborders, Trypanosomatina and Bodonina. Within the trypanoso matid clade, the genus Trypanosoma is a monophyletic group that divides int o two groups, the salivarian trypanosomes and the stercorarian trypanosomes . Dimastigella and Rhynchobodo, currently classified in the Bodonina, are b asal to the trypanosomatid-bodonid clade, suggesting that the suborder Bodo nina is paraphyletic. Further, Trypanoplasma borreli grouped within the Cry ptobia clade, and was more closely related to C. salmositica than to either C. bullocki or C. catostomi. This new molecular evidence, coupled with mor phological similarities of the two genera, again calls into question the va lidity of the genus Trypanoplasma.