Phylogeny of dimeric class II RNR. A PhyML UL3 phylogeny from an alignment of protein sequences of dimeric class II RNR enzyme containing the eukaryote T. vaginalis (arrow). Large top-level groups from the NCBI taxonomy have been colour-coded see inset legend, smaller groups are black. Viruses are in italics. The tree is not formally rooted; the pseudoroot is placed so as to be consistent with the global phylogeny in Figure 1c.