Rubroshiraia gen. nov., a second hypocrellin-producing genus in Shiraiaceae (Pleosporales).

Shiraiaceae is an important family in Pleosporales (Dothideomycetes), which includes medical fungi and plant pathogens. Two hypocrellin-producing taxa, Shiraia bambusicola and a novel genus Rubroshiraia gen. nov. , typified by Rubroshiraia bambusae are treated in this article. Maximum likelihood analysis, generated via RAxML (GTR+G model), using a combined SSU, LSU, TEF1 and RPB2 sequence dataset, shows that Rubroshiraia is close to Shiraia and belongs to the family Shiraiaceae. Descriptions, illustrations and a taxonomic key are provided for the genera in Shiraiaceae. Rubroshiraia morphologically differs from Shiraia in having small and dark ascostromata and filiform ascospores. Production of the ascostromatal metabolites, hypocrellin A and B, were examined by HPLC and spectrophotometer. The content of hypocrellin A and B of specimen HKAS 102255 ( R. bambusae ) is twice that produced by HKAS 102253 ( S. bambusicola ). To clarify the relationship between R. bambusae and Hypocrella bambusae , type material of the latter was examined and provided the illustration.