Genetic and Molecular Delineation of Three Sibling Species in the Hansenula polymorpha Complex

Genetic hybridization, molecular karyotyping and UP-PCR analysis showed that the taxonomic complex Hansenula polymorpha De Morais et Maia consists of three biological sibling species. H. angusta Teunisson et al. (= Pichia angusta (Teunisson et al.) Kurtzman) is not synonymous with H. polymorpha and must be reinstated as a separate species. The third sibling species is apparently a new taxon associated with Opuntia cacti. The sibling species are able to cross with each other but their interspecific hybrids are sterile.