Aeciospore surface structures ofGymnosporangium andRoestelia (Uredinales)

Aeciospore surface structures of 40Gymnosporangium species and 7Roestelia species were investigated with a scanning electron microscope. The surface structures of aeciospores were classified into 12 types on the basis of shape and size of processes. Surface structures of the aeciospores were stable within each species. Therefore, it is suggested that surface structures of aeciospores could be used as an important diagnostic criteria in identifyingGymnosporangium andRoestelia species. Contribution No 139, Laboratory of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba.