Oak decline is the most serious oak forests threat caused by a combination of biotic and abiotic factors in the world. In a survey on oak decline, 57 Biscogniauxia isolates were obtained from infected twigs and trunks of oak trees showing decline symptoms in Zagros forests, west of Iran. Based on morphology, cultural characteristics and DNA sequences data (ITS region and part of the β-tubulin gene) isolates were characterized as Biscogniauxia rosacearum and Obolarina persica. Most of the isolates belonged to B. rosacearum (40 isolates/70%). Pathogenicity test of B. rosacearum and O. persica on 2-year-old potted healthy oak seedlings confrmed the pathogenicity of both species on Quercus brantii. We report B. rosacearum for the frst time on Q. brantii, Q. infectoria and Q. libani in the world. Furthermore, O. persica is reported for the frst time on Q. libani and from West Azarbaijan Province. Based on the phylogenetic analyses, four species in two genera Camillea (C. obularia and C. tinctor) and Obolarina (O. dryophila and O. persica) are transferred to the genus Biscogniauxia Kuntze and two new combinations Biscogniauxia tinctor and Biscogniauxia persica are introduced.
