Species of the fungal genus Arthrinium (Sordariomycetes, Amphisphaeriales, Apiosporaceae) are often found on bamboo in Asia. They are endophytes, saprobes and important plant pathogens. The genus Arthrinium currently contains 92 species and is widely distributed in North and South America, Europe, Africa, Asia and Oceania. In this study, a new species, Arthrinium bambusicola sp. nov., is described and illustrated. The new taxon is characterised by oval to broadly or irregularly round, medium brown, multi-guttulate to roughened, granular conidia, with finely pale slits in the outer edges. Arthrinium bambusicola can be distinguished from the closest related species A. gutiae by its conidial characteristics. Phylogenetic analyses of a four-locus dataset (ITS, LSU, TEF1, TUB2) confirm that A. bambusicola is a distinct new species.