Identification and characterization of two new Gymnosporangium species causing rust on Juniperus rigida in China

A serious Juniperus rigida rust disease was found in Gansu Province, China. The disease incidence is approximately 80-90%. We also found rust disease on both Cotoneaster multiflorus and Sorbus in the same location. Two novel Gymnosporangium species were identified from the infected plants. Based on morphological observations and phylogenetic analyses, we describe the two new taxa as G. gansuense and G. granulatosporum. We also determined their life cycles. Moreover, this study documented a novel aeciospore surface structure with two different surface types on one aeciospore. We describe it here as "granular."