The sterile microfilamentous lichenized fungi Cystocoleus ebeneus and Racodium rupestre are relatives of plant pathogens and clinically important dothidealean fungi.

The phylogenetic positions of the always-sterile microfilamentous lichens Cystocoleus ebeneus and Racodium rupestre were studied in a phylogenetic framework using sequence data of 5' nuSSU, nuLSU, and mtSSU rDNA. The analysis reveals that both genera are ascomycetes and belong to Dothideomycetidae: they are not close to lichenized members within the subclass, but rather belong to Capnodiales. The macroscopically scarcely distinguishable C. ebeneus and R. rupestre do not form a monophyletic group. The well-supported clade of R. rupestre is basal to the one in which C. ebeneus is close to Mycosphaerellaceae. This study provides another example of ascomycetes with very different life-styles and ecologies being closely related.