Abstract
The Chinese polymitarcyid mayfly Ephoron nanchangi (Hsu, 1936) was originally named upon females, which were lost. The exact morphology has not been presented until now. The newly collected materials of this species, which include nymphs, female subimagos and male imagos, show it is a valid species with unique morphology, distinguishable from congeners by its short and strong nymphal mandibular tusks, long distance between forks of Rs and MA in imaginal forewings.