Unveiling Gymnosporangium corniforme, G. unicorne, and G. niitakayamense sp. nov. in Taiwan

Three rust fungi from high mountains and pear-producing areas in Taiwan were described using morphological and molecular data based on 34 specimens. Gymnosporangium corniforme was demonstrated to produce spermogonia and aecia on Sorbus randaiensis based on molecular analyses and inoculation experiments. The pear rust pathogen G. unicorne was discovered in Taiwan for the first time. Gymnosporangium niitakayamense sp. nov. was observed on the leaves of Photinia niitakayamensis. It was distinct from other species in peridial cell wall structures, i.e., smooth outer wall, rugose side wall, and coralloid projections on the inner wall, and in having echinulate aeciospores.