Roussoella yangjiangensis sp. nov. (Roussoellaceae, Pleosporales), A Holomorphic Fungus in Guangdong Province, China

Bambusicolous fungi comprise a diverse assemblage of species that inhabit a wide range of bamboo species. During an ongoing investigation of bambusicolous fungi in Guangdong Province, China, two interesting strains were isolated from decaying culms of Phyllostachys edulis and Bambusa sinospinosa. Based on morphological characteristics and phylogenetic analysis, the two collections are identified as the sexual and asexual states of a new species, Roussoella yangjiangensis. Roussoella yangjiangensis is characterized by bi-loculate ascostromata, cylindrical asci, fusiform, yellowish brown to dark brown, 1-septate, longitudinally striated ascospores with a sheath, and an asexual morph producing pseudostromatic pycnidia, monophialidic conidiogenous cells, and cylindrical to oblong, brown, aseptate conidia. Phylogenetic analysis of combined LSU, ITS, tef1-α, and rpb2 sequence data reveals that R. yangjiangensis is closely related to R. aseptata and R. yunnanensis, but forms a separate branch. A morphological comparison among these phylogenetically related taxa and other morphologically similar species further support the establishment of the novel species. In this study, the polyphyletic nature of Roussoella is also revealed, and the classification of R. arundinacea, R. chinensis and R. mexicana is discussed.