Phylogenetic analyses and morphological studies reveal two new species of Biscogniauxia (Xylariales, Ascomycota) from Hainan Tropical Rainforest National Park, China.

The species diversity of the family Graphostromataceae is poorly understood in tropical regions. The present work concerns a survey of wood-inhabiting macrofungi from the Hainan Tropical Rainforest, which is located in south-central Hainan Province. This study introduces two new species of Biscogniauxia, viz., B. diaoluoshanensis sp. nov. and B. jianfengensis sp. nov., which are herein described based on morphological and molecular evidence. Morphologically, B. diaoluoshanensis is characterized by applanate stromata, ovoid to pyriform perithecia, and ascospores with a conspicuous straight, almost spore-length germ slit. Biscogniauxia jianfengensis is distinguished by applanate to slightly pulvinate stromata, tubular perithecia, ascospores with an inconspicuous, unilateral, straight, spore-length germ slit, bearing an opaque cellular appendage on one side. The phylogenetic analysis inferred from ITS, RPB2 and TUB2 sequence data confirmed that the two new species are distinct within the genus Biscogniauxia. Detailed descriptions, illustrations, and phylogenetic analysis results are provided for each new species, and a dichotomous identification key is presented for the genus as well.