Arthrinium setostromum (Apiosporaceae, Xylariales), a novel species associated with dead bamboo from Yunnan, China

Arthrinium setostromum sp. nov., collected from dead branches of bamboo in Yunnan Province of China, is described and illustrated with the sexual and asexual connections. The sexual morph of the new taxon is characterized by raised, dark brown to black, setose, lenticular, 1–3loculate ascostromata, immersed in a clypeus, unitunicate, 8-spored, broadly clavate to cylindricclavate asci and hyaline apiospores, surrounded by an indistinct mucilaginous sheath. The asexual morph develops holoblastic, monoblastic conidiogenesis with globose to subglobose, dark brown, 0–1-septate conidia. Arthrinium setostromum can be distinguished from other phylogenetically closely related species by its setose ascostroma, with setae raising through a split of the clypeus. Maximum likelihood, maximum parsimony and bayesian inference analyses based on a catenated ITS, LSU, TEF1-α and TUB2 DNA sequence dataset demonstrate that A. setostromum is a distinct new species phylogenetically closely related to A. garethjonesii, and clusters with A. bambusae, A. mytilomorphum and A. subroseum.