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

Abstract

Shiraiaceae is an important family in Pleosporales (Dothideomycetes), which includes medical fungi and plant pathogens. Two hypocrellin-producing taxa, <i>Shiraia bambusicola</i> and a novel genus <i>Rubroshiraia</i> <b>gen. nov.</b>, typified by <i>Rubroshiraia bambusae</i> 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 <i>Rubroshiraia</i> is close to <i>Shiraia</i> and belongs to the family Shiraiaceae. Descriptions, illustrations and a taxonomic key are provided for the genera in Shiraiaceae. <i>Rubroshiraia</i> morphologically differs from <i>Shiraia</i> 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 (<i>R. bambusae</i>) is twice that produced by HKAS 102253 (<i>S. bambusicola</i>). To clarify the relationship between <i>R. bambusae</i> and <i>Hypocrella bambusae</i>, type material of the latter was examined and provided the illustration.