Hemianax or Anax: John - the species was first described as Aeschna papuensis by Burmister in 1839, and as Anax congener by Rambur in 1842. Not sure when or by whom it was put under Hemianax (possibly Gunther Theischinger but I'm only guessing), but the current accepted name in the Atlas of Living Australia (ALA), the Australian Faunal Directory (AFD), and the World Odonata List (WOL) is Anax papuensis.
Cheers, Harvey