Phylum Ascomycota Caval.-Sm. (1998) - sac fungi
   Subphylum Saccharomycotina O.E. Erikss. & Winka (1997) [monotypic] - budding yeasts
     Class Saccharomycetes O.E. Erikss. & Winka (1997), nom. inval. [monotypic] see Class Saccharomycetes G.Winter (1880)
       Order Saccharomycetales Luerss. (1877)
         Genus Phialoascus Redhead & Malloch (1977), incertae sedis