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

Abstract

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, Adustochaete albomarginata, Ad. punctata, Alloexidiopsis grandinea and Al. xantha collected from southern China, are proposed, based on a combination of morphological features and molecular evidence. Adustochaete albomarginata 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). Adustochaete punctata 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). Alloexidiopsis grandinea 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, Alloexidiopsis xantha 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 Adustochaete and Alloexidiopsis within the order Auriculariales, individually. The phylogenetic tree inferred from the ITS sequences highlighted that Ad. albomarginata was retrieved as a sister to Ad. yunnanensis and the species Ad. punctata was sister to Ad. rava. The topology, based on the ITS sequences, showed that Al. grandinea was retrieved as a sister to Al. schistacea and the taxon Al. xantha formed a monophyletic lineage. Furthermore, two identification keys to Adustochaete and Alloexidiopsis worldwide are provided.