Characterisation and phylogenetic relationships of Anisogramma virgultorum and A. anomala in the Diaporthales (Ascomycota)

The two diaporthalean fungi Anisogramma virgultorum and A. anomala are biotrophic parasites. A. virgultorum causes stromatal cankers on young shoots of birch whereas A. anomala infects young branches of Corylus avellana. Although previous classifications based on morphological characteristics placed both species in the Gnomoniaceae, Diaporthales, their taxonomic position within the order and their relationship to each other required further clarification. We determined the nucleotide sequences of the ITS and partial LSU nu-rDNA regions of both species. A putative second teleomorph form of A. virgultorum, described in the literature as the 'single perithecial form', was also included in the analysis. Based on phylogenetic analyses of LSU sequences, the stromatal forms of A. virgultorum and A. anomala were part of a well-supported monophyletic sister clade to the Gnomoniaceae. The single perithecial form was placed within a clade containing representative members of the Gnomoniaceae, separate from species of Anisogramma. These results indicate that the single perithecial form of A. virgultorum actually represents an unrelated and as yet unidentified species of Gnomoniaceae. A morphological description of asci and ascospores of the three species is given. A Wilcoxon two sample test revealed that asci of the stromatal form of A. virgultorum were significantly shorter than those of the single perithecial species. Ascospores of the stromatal form of A. virgultorum were significantly shorter and wider than those of the single perithecial species.