Additional new species of Xenodidymella from pasture-medicinal plants in Iran

Xenodidymella species have a wide range of hosts and can be found as pathogens and saprobes. In this study, two new species of Xenodidymella were found from leaf diseases of three pasture-medicinal plants in Ilam Province, in the west of Iran, and proposed here as X. ilamica and X. scandicis spp. nov. These species were identified based on morphological features and phylogenetic analyses of the internal transcribed spacer regions 1 & 2 and 5.8S nrDNA (ITS), partial beta-tubulin gene (tub2), and partial RNA polymerase II second largest subunit (rpb2) gene. The four Xenodidymella strains isolated in this study were delimited into two sister clades, with the two isolates of X. ilamica from the leaf spot of Colchicum speciosum and Ficaria kochii and two isolates of X. scandicis from leaf blight of Scandix pecten-veneris. Morphologically, X. scandicis produces larger, ostiolate or poroid pycnidia in vitro, while pycnidia in the cultures of X. ilamica are non-ostiolate and smaller. Some pycnidia in old cultures of X. scandicis produce a neck, but a distinct neck in X. ilamica has not been observed. Moreover, three plants under study are new hosts for the genus Xenodidymella.