Abstract
Tristratiperidium microsporum gen. et sp. nov. (Xylariales) is introduced to accommodate a taxon isolated from dead leaves of Arundo plinii, collected in Italy. The sexual and asexual morphs are described and illustrated and compared with similar taxa. Phylogenetic analysis of combined Internal Transcribed Spacer (ITS) and Large Subunit (LSU) rRNA sequence data show the relationships of T. microsporum with other genera in the Xylariales. Tristratiperidium microsporum clusters with the hyphomycete Subramaniomyces fusisaprophyticus in the order Xylariales, in the clade comprising Apiosporaceae, Hyponectriaceae, Melogrammataceae, and Pseudomassariaceae. The phylogenetic relationships of T. microsporum and allied fungi are discussed and its placement in the Xylariales genera incertae sedis is suggested.