Taxonomic circumscription of melanconis-like fungi causing canker disease in China

Melanconis-like species comprise latent fungal pathogens with a wide range of woody hosts. Taxonomy of these pathogens is difficult due to their uninformative descriptions and similar asexual morphology. Based on molecular phylogenies, many species of this group were placed in various families of Diaporthales. In this study, eight species of melanconis-like fungi were isolated from Betula albosinensis, B. platyphylla (Betulaceae), Cornus controversa (Cornaceae), Corylus mandshurica (Betulaceae) and Juglans regia (Juglandaceae) in China. These species were phylogenetically placed in three families of Diaporhthales, i.e. Juglanconis juglandina, J. oblonga (Juglanconidaceae), Melanconiella betulicola sp. nov., M. corylina sp. nov. (Melanconiellaceae), Melanconis betulae, Ms. itoana, Ms. stilbostoma (Melanconidaceae) and one new genus, Sheathospora (Melanconiellaceae). Sheathospora is proposed to accommodate Melanconiella cornuta with conical and discrete pycnidia with aseptate, hyaline, cylindrical to ellipsoidal conidia with distinct hyaline sheath on branches of Cornus controversa. Combined analyses of ITS, LSU, CAL, RPB2 and TEF1-α sequence data were used to construct the molecular phylogeny. Additionally, we provided separate phylogenetic trees for three families (Juglanconidaceae, Melanconidaceae and Melanconiellaceae) to show the species distribution of melanconis-like fungi in China.