To study the phylogeny and evolution of archiascomycetes, we determined the full sequence of the nuclear 18S rRNA gene from 14 Taphrina species and 2 Protomyces species, and the partial sequence of Schizosaccharomyces japonicus var. japonicus. The sequences were phylogenetically analyzed by the neighbor-joining, maximum parsimony, and maximum-likelihood methods. We also looked at their principal phenotypic characters and genotypic character. Relationships within the Ascomycota are concordant with the previously published phylogenies inferred from 18S rDNA sequence divergence and divide the archi-, hemi- and euascomycetes into distinct major lineages. All the trees show that, within the archiascomycete lineage, 11 of the 14 Taphrina species and the 2 Protomyces species are monophyletic. A core group of Taphrina and Protomyces is always monophyletic. The evidence from molecular and phenotypic characters such as cell wall sugar composition, ubiquinone, cell wall ultrastructure, and mode of conidium ontogeny, strongly suggests that 'T'. californica CBS 374.39, 'T'. maculans CBS 427.69 and 'T. farlowii CBS 376.39 should be excluded from the archiascomycete lineage. 'Taphrina' farlowii CBS 376.39 groups with Candida albicans in the Saccharomycetales, whereas 'T'. californica CBS 374.39 and 'T'. maculans CBS 427.69 have a basidiomycete affinity and group with Tremellalean members in the hymenomycete lineage. Schizosaccharomyces is monophyletic. The strictly anamorphic yeast Saitoella complicata groups with the apothecial ascomycete Neolecta vitellina rather than the Taphrina/Protomyces branch.
- 18S ribosomal RNA gene phylogeny