Discovery of a new species of the complex from Iran and antagonistic activities of spp. against the Ash Dieback pathogen, , in dual culture.

During a survey of xylarialean fungi in Northern Iran, several specimens that showed affinities to the complex were collected and cultured. A comparison of their morphological characters, combined with a chemotaxonomic study based on high performance liquid chromatography, coupled with diode array detection and mass spectrometry (HPLC-DAD/MS) and a multi-locus phylogeny based on ITS, LSU, and DNA sequences, revealed a new species here described as . In addition, was also encountered. Concurrently, an endophytic isolate of the latter species showed strong antagonistic activities against the Ash Dieback pathogen, , in a dual culture assay in our laboratory. Therefore, we decided to test the new Iranian fungi for antagonistic activities against the pathogen, along with several cultures of other species that are related to . Our results suggest that the antagonistic effects of spp. against are widespread and that they are due to the production of antifungal phomopsidin derivatives in the presence of the pathogen.