A revision of the species Notonecta xyphiale (Popov, 1964) (Heteroptera: Notonectidae)

New fossil specimens of Notonecta xyphiale ( Popov, 1964) in different instars have been collected from the Yixian Formation in Liaoning Province, China. A brief review of previous studies and additional descriptive notes on N. xyphiale are given. According to these specimens, the diagnosis of the genus Notonecta is revised.

► The diagnosis of the genus Notonecta is revised for the fossil species.
► There are 4 fossil species in Notonecta.
► Both adults and nymphs of Notonecta xyphiale are described.
► Nymph’s tarsi probably have one segment.
► Notonecta xyphiale may not have protuberance in middle femora.