The nymph and imago of Chinese mayfly Siphlonurus davidi (Navás, 1932).

The imagos and nymphs of Siphlonurus davidi (Navas, 1932) are described for the first time. The adult has colourful wings and cross veins, the MP is forked asymmetrically at its base, a long cubital area is present with more intercalaries, and it has a relatively simpler penis and larger hindwings compared to its congeners. The venation and genitalia show that it is a plesiomorphic species in the genus. A key to the Asian species of Siphlonurus with coloured wings is provided in conclusion.