The phylogenetic position of Rhopalostroma as inferred from a polythetic approach

The xylariaceous genus Rhopalostroma comprises a small conglomerate of stromatic, angiosperm-associated pyrenomycetes, which have so far exclusively been reported from the palaeotropics, above all from tropical Africa and South Asia. Morphological and chemotaxonomic studies had suggested their close relationship to the genera Daldinia and Hypoxylon. However, those results were mainly based on herbarium specimens, and no molecular phylogenetic data were available on Rhopalostroma. During a foray in Côte d'Ivoire, fresh material of R. angolense was collected, cultured and studied by microscopic methods and by secondary metabolite profiling using high performance liquid chromatography coupled with diode array and mass spectrometric detection. In addition, ITS nrDNA sequences of the cultures were generated and compared to those of representative Xylariaceae taxa, to evaluate the phylogenetic affinities of this fungus. The results showed that R. angolense is closely related to the daldinoid Xylariaceae, and in particular to the predominantly neotropical genera Phylacia and Thamnomyces.