Phylogeny and classification of the Digenea (Platyhelminthes ...

P.D. Olson et al. / International Journal for Parasitology 33 (2003) 733–755 745Fig. 6. Revised classification of the Digenea based on the results of Bayesian inference of lsrDNA and ssrDNA combined (see Fig. 3).formed either sister clades (lsrDNA) or separate lineages(ssrDNA). The third lineage comprised the blood-flukegroups (iii) the Sanguinicolidae, Schistosomatidae andSpirorchidae, together with the Clinostomidae. Analysesof lsrDNA alone failed to support monophyly of theSanguinicolidae, although the high rate of divergence ofthe sanguinicolids (Fig. 3) may account for this, and for thedifferences in the relative positions of the four familiesamong the analyses (Fig. 1). In the combined analyses (Fig.2), however, both methods resolved the monophyly of theSanguinicolidae and yielded congruent, fully resolvedtopologies with strong nodal support.Interrelationships of the Plagiorchiida were less consistentamong the different genes and methods of analysis (Fig.1), but as described above, showed greater consistencybetween methods of analysis when both genes werecombined (Fig. 2). In combined analyses, the Bivesiculidaeformed the basal lineage of the clade followed by theTransversotrematidae (BI; Figs. 2 and 3) or by all remainingtaxa (maximum parsimony; Fig. 2). As with the sanguini-