Taxonomy and phylogeny of Sidera (Hymenochaetales, Rickenella clade) from China and North America revealing two new species.

, belonging to the clade of Hymenochaetales, is a worldwide genus with mostly poroid hymenophore of wood-inhabiting fungi. Two new species in the genus, and , are described and illustrated from China and North America based on morphological and molecular evidence. They were mainly found growing on rotten wood of , and . is characterized by annual, resupinate basidiomata with silk sheen when dry, round pores (9-11 per mm), a dimitic hyphal system, and allantoid basidiospores measuring 3.5-4.2 × 1 μm. is characterized by annual, resupinate basidiomata with cream to pinkish buff dry pore surface, angular pores (6-7 per mm), a dimitic hyphal system, and allantoid basidiospores measuring 3.9-4.1 × 1-1.1 μm. Phylogenetic analysis based on a combined 2-locus dataset [ITS1-5.8S-ITS2 (ITS) + nuclear large subunit RNA (nLSU)] shows that the two species are members of , and they are compared with morphologically similar and phylogenetically related species, respectively. An identification key to 18 accepted species of in worldwide is provided.