Macronychia (Moschusa) rubesca sp. nov. is described from Australia and represents the first record of this genus from the Australasian region. An updated key to the world species of Macronychia is provided. In addition, molecular markers are analysed to place Macronychia Rondani within the most recent phylogeny of the subfamily Miltogramminae. The genus is resolved as a monophyletic clade and placed within the 'higher' miltogrammines as sister to Oebalia Robineau-Desvoidy.