Taxonomy and phylogeny of Auriculariales (Agaricomycetes, Basidiomycota) with descriptions of four new species from south-western China

The wood-inhabiting fungi play an integral role in wood degradation and the cycle of matter in the ecological system. They are considered as the "key player" in wood decomposition, because of their ability to produce lignocellulosic enzymes that break down woody lignin, cellulose and hemicellulose. In the present study, four new wood-inhabiting fungal species, <i>Adustochaetealbomarginata</i>, <i>Ad.punctata</i>, <i>Alloexidiopsisgrandinea</i> and <i>Al.xantha</i> collected from southern China, are proposed, based on a combination of morphological features and molecular evidence. <i>Adustochaetealbomarginata</i> is characterised by resupinate basidiomata with cream to buff, a smooth, cracked, hymenial surface, a monomitic hyphal system with clamped generative hyphae and subcylindrical to allantoid basidiospores (12-17.5 × 6.5-9 µm). <i>Adustochaetepunctata</i> is characterised by resupinate basidiomata with cream, a smooth, punctate hymenial surface, a monomitic hyphal system with clamped generative hyphae and subcylindrical to allantoid basidiospores (13.5-18 × 6-8.2 µm). <i>Alloexidiopsisgrandinea</i> is characterised by resupinate basidiomata with buff to slightly yellowish, a grandinioid hymenial surface, a monomitic hyphal system with clamped generative hyphae and allantoid basidiospores (10-12.3 × 5-5.8 µm). Additionally, <i>Alloexidiopsisxantha</i> is characterised by resupinate basidiomata with cream to slightly buff, a smooth hymenial surface, a monomitic hyphal system with clamped generative hyphae and subcylindrical to allantoid basidiospores measuring 20-24 × 5-6.2 µm. Sequences of the internal transcribed spacers (ITS) and the large subunit (nrLSU) of the nuclear ribosomal DNA (rDNA) markers of the studied samples were generated. Phylogenetic analyses were performed with the Maximum Likelihood, Maximum Parsimony and Bayesian Inference methods. The phylogram, based on the ITS+nLSU rDNA gene regions, revealed that four new species were assigned to the genera <i>Adustochaete</i> and <i>Alloexidiopsis</i> within the order Auriculariales, individually. The phylogenetic tree inferred from the ITS sequences highlighted that <i>Ad.albomarginata</i> was retrieved as a sister to <i>Ad.yunnanensis</i> and the species <i>Ad.punctata</i> was sister to <i>Ad.rava</i>. The topology, based on the ITS sequences, showed that <i>Al.grandinea</i> was retrieved as a sister to <i>Al.schistacea</i> and the taxon <i>Al.xantha</i> formed a monophyletic lineage. Furthermore, two identification keys to <i>Adustochaete</i> and <i>Alloexidiopsis</i> worldwide are provided.