Partial 18S ribosomal RNA nucleotide sequences were determined of all
known species of ballistoconidium-forming yeasts. Complete 18S rDNA nu
cleotide sequences were determined in three Udeniomyces species and se
ven Bullera species. Phylogenetic analysis indicates that Bullera is p
olyphyletic, while Udeniomyces is monophyletic. The phylogenetic relat
ionships of these yeasts correlate well with the biochemical compositi
on of the cell wall, namely presence or absence of xylose, but not wit
h the number of isoprenoids of the ubiquinone molecule.