Description of a new species of the genus Ameletus Eaton, 1885 (Ephemeroptera, Ameletidae) from Yunnan, China.

A new species with primitive characteristics, Ameletus daliensis Tong, sp. nov., is described, based on the morphology of imago, larva and egg with molecular data of the mitochondrial COI from Mount Cangshan, Dali, China. The new species is closely related to one of the most primitive mayflies, Ameletus primitivus Traver, 1939, by sharing persistent mouthparts in the alate stage, but it can be distinguished from the latter by the morphological differences of the mouthpart remains, wings and genitals in the imaginal stage. Both morphological and molecular evidence support that A. daliensis Tong, sp. nov. is a new member of the genus Ameletus. The discovery of the new species could help understand the origin and evolution of the genus Ameletus.