Phylogeny and taxonomy of Nigroporus (Polyporales, Basidiomycota) with four new species from Asia and Oceania

Nigroporusvinosus (Berk.) Murrill, first described from North America, was considered to be a common species in China. The existence of a species complex is confirmed through a phylogenetic analysis of samples examined. Based on morphological examination and molecular evidence, four new species are described as Nigroporusaustralianus, N.austroasianus, N.subvinosus and N.yunnanensis. They are characterized by pileate, effused-reflexed to resupinate, purplish, vinaceous to brown basidiomata when fresh, mostly becoming brown when dry. Nigroporusaustralianus is characterized by narrower basidiospores measuring 3.4-4.1 × 1.3-1.5 µm, thicker contextual hyphae measuring 3.2-6.4 µm in diam and a geographical distribution in Australia. Nigroporusaustroasianus is characterized by smaller pores measuring 10-13 per mm, generative hyphae dominant in the tube trama, small basidiospores measuring 3-4.1 × 1.5-2 μm and a distribution in Malaysia and tropical to subtropical regions of China. Nigroporussubvinosus is characterized by skeletal hyphae with thin to slightly thick walls, barrel- to pear-shaped basidia, and long cystidioles measuring 10-18 µm and is common in Asia. Nigroporusyunnanensis is characterized by thinner pilei measuring 2.5 mm thick at the base, bigger basidiospores measuring 4-4.5 × 1.9-2.2 μm and is found only in Yunnan. The 2-gene (ITS+nLSU) analysis of the Steccherinaceae indicated that the four new species nested in the Nigroporus clade. The 3-gene (ITS+nLSU+TEF1) analysis of the genus Nigroporus showed that N.australianus formed a monophyletic lineage, N.subvinosus was sister to N.austroasianus and N.yunnanensis, and N.austroasianus was sister to N.yunnanensis. Furthermore, N.vinosus sensu stricto is also distributed in Asia.