Phylogeny of the ascomycetous yeasts and the renaming of Pichia anomala to Wickerhamomyces anomalus

In this review, the phylogeny of the ascomycetous yeasts is discussed, with emphasis on the genus Pichia and its synonym Hansenula. The genus Pichia, as defined from phenotype, had nearly 100 assigned species, but the number of species has been reduced to 20 following phylogenetic circumscription on Pichia membranifaciens, the type species of the genus. The remaining species of Pichia have been reassigned to 20 different genera, many of which are newly described, such as Wickerhamomyces. The reason for reclassification of Pichia anomala in the genus Wickerhamomyces is discussed.