The genus Pyrenomyxa and its affinities to other cleistocarpous Hypoxyloideae as inferred from morphological and chemical traits.

Types and authentic specimens of Hypoxylon piceum, Pulveria porrecta, and Pyrenomyxa invocans were studied for morphological traits and extrolite (= secondary metabolite) profiles generated by analytical HPLC with UV-visual and mass spectrometric detection. The orange stromatal pigments of P. invocans are rubiginosin A and mitorubrinol. It lacks three different types of extrolites (BNT, macrocarpone and hypomiltin) that are known from Hypoxylon taxa and occur in H. piceum and P. porrecta. In agreement with morphological traits, the latter two names are regarded as synonymous and transferred to Pyrenomyxa. Another species from Eastern Russia, Pyrenomyxa morganii sp. nov., is recognized. It contains yet unidentified azaphilones besides BNT and orsellinic acid, and its culture produces 5-methylmellein and a virgariella-like anamorph. These findings suggest a close relationship of Pyrenomyxa to Hypoxylon and emphasize the utility of chemotaxonomic traits for fungal taxonomy in general. Pyrenomyxa is accepted ad interim until the phylogenetic relationships among Hypoxylon have been further evaluated by means of chemotaxonomic, morphological and molecular methods.