The article mainly concerns the confused state of affairs existing in 2 out of 4 well-known yet wrongly interpreted species of Austroagrion. a genus centred in Australia but with 2 members occurring also outside the continent. The history of these is analysed and their correct status definitely established, using distinctive characters of structure and colour design, which are illustrated. An examination of the holotype of A. cyane (Selys), the type-species of the genus, revealed that it is conspecific with the West Australian A. coeruleum Tillyard, the last-mentioned name thus becoming a synonym of cyane. Inferentially, the species so far mistaken for cyane by all post-Selysian authors, is the widespread and locally common damselfly chiefly occurring in the eastern States of the continent. Consequently, this eastern opponent of A. cyane now requires a new name, for which watsoni, nom. nov., is here proposed as a substitute. The above explanation is followed by a new descriptive key to the identification of all 4 taxa so far known. After that, 3 of these species are briefly discussed, each supplied with a bibliography and locality lists of the material examined, A brief characterization is also given of a slightly aberrant population of A. watsoni, recently discovered in New Caledonia, a new element in the dragonfly fauna of that island.