The Reared Male Imago of Rhoenanthus sapa Nguyen et Bae, 2004 from China Showing Its Basal Position in the Genus (Ephemeroptera: Potamanthidae)

The male imago of Rhoenanthus sapa Nguyen et Bae, 2004, which had not been previously reported, was reared for the first time from mature nymph in China. Morphologically, they have lighter bodies and wings and simpler genitalia than congeners. Combined with its nymphal features (relatively short and curved mandibular tusks), this species links the genera Rhoenanthus Eaton, 1881 and Potamanthodes Ulmer, 1920 together and throws some new light on the evolution of the family Potamanthidae.