Didymella corylicola sp. nov., a new fungus associated with hazelnut fruit development in Italy

A new fungal species constantly associated with hazelnut ( Corylus avellana ) fructification starting from its primordia is described. The fungus is associated with hazelnut fruit during all their developmental stages, being consistently more present in spring (March–June). A 4-year survey has been conducted, from young fruit formation to full kernel maturity including also the post-harvest phase, to collect fungi associated with damaged/discoloured kernels. A collection of 60 isolates of a new species has been obtained in this study, which is here described as Didymella corylicola sp. nov. Multi-locus phylogenies based on four genomic loci (nuITS and LSU rDNA, RPB2 and TUB2 ) in combination with morphological data confirmed the fungus to represent a new species of Didymella (Didymellaceae). The occurrence of D . corylicola sp. nov. might have an impact on the quality of hazelnut production by contributing to kernel defects.