To resolve a prevailing nomenclatorial confusion present in the genus Aciagrion, A. tillyardi Laidlaw, 1919 is placed in synonymy of A. approximans (Selys, 1876). The neotype of “Pseudagrion approximans”, a male specimen from Khasi Hills preserved in Coll. Selys Longchamps at RBINS, is designated to replace the lost holotype, which was an incomplete specimen of…