Abstract
Laetiporus is a cosmopolitan genus of brown rot fungi. In this study, L.medogensis and L.xinjiangensis are described as new species from western China, based on morphological and molecular evidence. L.medogensis has only been found on gymnosperms so far and is distinguished by pinkish-buff to clay-buff pileal surface and buff-yellow pore surface, azonate to faintly zonate pileus and ellipsoid to ovoid basidiospores (5-6.2 × 4.2-5.2 μm). L.xinjiangensis is found on angiosperms and is characterised by pale-buff to clay-pink pileal surface, cream to light yellow pore surface, azonate to faintly zonate pileus, large pores (2-3 per mm) and small basidiospores (4.5-5 × 3-4.2 μm). The phylogeny of Laetiporus is reconstructed with multi-gene sequences including the internal transcribed spacer regions (ITS), the large subunit (nrLSU) and small subunit (nrSSU) of the nuclear ribosomal RNA gene, the small subunit of the mitochondrial rRNA gene (mtSSU), the translation elongation factor 1-α gene (EF-1α) and the second subunit of RNA polymerase II (RPB2). The results show that L.medogensis and L.xinjiangensis formed two distinct lineages belonging to Laetiporus. Illustrated descriptions of the two new species are presented. An identification key to species of L.sulphureus complex is provided.