Twelve wood decaying species of Phlebia and Phanerochaete were analysed by RFLP (restriction fragment length polymorphism)
analysis of an 18S rRNA gene fragment and an ITS region. The data obtained by different restriction endonucleases were used to
construct phenograms based on the UPGMA algorithm. PCR-RFLP within the 18S rRNA gene was sufficient to distinguish between
Phlebia species but did not show variation among Phanerochaete spp. ITS region amplified from Phlebia spp. varied in length from
570–745 bp. The smallest ITS fragment was amplified from P. subcretacea and the longest from P. hydnoides. The size of ITS
fragments amplified from Phanerochaete spp. was uniform (635 bp), except for the ITS from two P. sanguinea strains (690 bp). RFLP
analysis within ITS amplified from Phanerochaete spp. distinguished between them. Results from PCR-RFLP of 18S rRNA and ITS
strongly suggest that Phiebia gigantea is closely related to Phanerochaete. Morphological characteristics (lack of clamp connections in
hymenium, well developed subiculum) further support this hypothesis.