Five New Species of Wood-Decaying Brown-Rot Fungi within Postiaceae (Polyporales, Basidiomycota) from Xinjiang, Northwest China

Brown-rot fungi are an important group of wood-decaying fungi, but there has been limited research on the species diversity of brown-rot fungi in Xinjiang, China. During an investigation of brown-rot fungi in Xinjiang, from July 2018 to July 2023, five new species belonging to the family Postiaceae were discovered based on morphological and molecular evidence. <i>Amaropostia altaiensis</i> is characterized by a conchate pileus, circular pores (5-8 per mm), and growing on <i>Populus</i>. <i>Amaropostia tianshanensis</i> is characterized by a flabelliform-to-conchate pileus, angular pores (5-6 per mm), and growing on <i>Picfea</i>. <i>Cyanosporus latisporus</i> is characterized by a hirsute and dark greyish blue pileal surface with fresh, larger pores (3-6 per mm) and broad basidiospores (4.3-5.9 × 1.4-2 µm). <i>Cyanosporus tianshanensis</i> is characterized by a smooth and white-to-cream pileal surface with fresh, smaller pores (6-9 per mm). <i>Osteina altaiensis</i> is characterized by a light mouse-grey-to-honey-yellow pileal surface, smaller pores (4-6 per mm), and slightly wide basidiospores (5-6 × 1.7-2.2 µm). Each of these five new species form independent lineages in phylogenetic analyses based on the seven gene loci (ITS + nLSU + nSSU + mtSSU + TEF1 + RPB1 + RPB2). This research enriches the diversity of brown-rot fungi species, while also demonstrating the substantial discovery potential and research value of brown-rot fungi in Xinjiang.