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 Betulaalbosinensis, B.platyphylla (Betulaceae), Cornuscontroversa (Cornaceae), Corylusmandshurica (Betulaceae) and Juglansregia (Juglandaceae) in China. These species were phylogenetically placed in three families of Diaporhthales, i.e. Juglanconisjuglandina, J.oblonga (Juglanconidaceae), Melanconiellabetulicola sp. nov., M.corylina sp. nov. (Melanconiellaceae), Melanconisbetulae, Ms.itoana, Ms.stilbostoma (Melanconidaceae) and one new genus, Sheathospora (Melanconiellaceae). Sheathospora is proposed to accommodate Melanconiellacornuta with conical and discrete pycnidia with aseptate, hyaline, cylindrical to ellipsoidal conidia with distinct hyaline sheath on branches of Cornuscontroversa. 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.