Phylogeny and taxonomy of the genus Abundisporus (Polyporales, Basidiomycota)

Phylogenetic and taxonomic studies of Abundisporus were carried out. Inferred from phylogenies based on DNA sequences of multiple loci including the internal transcribed spacer (ITS) regions, the large subunit nuclear ribosomal RNA gene (nLSU), the small subunit mitochondrial rRNA gene sequences (mtSSU) and the translation elongation factor 1-alpha gene (tef1), species falling under the current concept of Abundisporus represent a monophyletic lineage, which belongs to the core polyporoid clade. The genus is morphologically characterized by resupinate to pileate basidiocarps with pale umber to deep purplish brown or greyish to umber brown context; a dimitic hyphal structure with yellow to pale brown skeletal hyphae; pale yellowish, non-dextrinoid, ellipsoid basidiospores with slightly thick walls; and tissues that turn brown in KOH. Seven taxa have been recognized in the genus with both morphological and molecular evidence. A new species, A. mollissimus, is described here. The new species is characterized by its soft, perennial, effused-reflexed to pileate basidiocarp, a dimitic hyphal system with dextrinoid, cyanophilous and narrower skeletal hyphae, and ellipsoid basidiospores measuring 4-4.5x3-3.5 mu m. Illustrated descriptions and a key to all species in this genus are provided.