Platybaetis gagadjuensis Suter, 2001, an Australian mayfly species originally assigned to the genus Platybaetis Müller-Liebenau, 1980, has long presented morphological inconsistencies with its generic placement. Recent comparative analyses have demonstrated that this species fully corresponds to the newly established subgenus Papuafiliola Kaltenbach, Kluge & Gattolliat, 2025. The description of this subgenus, and its placement within the genus Papuanatula Lugo-Ortiz & McCafferty, 1999, entails a significant revision of the generic concept and diagnostic characters. Accordingly, we formally propose the new combination Papuanatula (Papuafiliola) gagadjuensis comb. nov. This reassignment does not require any modification to the existing diagnoses of the genus or subgenus. Papuanatula (P.) gagadjuensis comb. nov. can be distinguished from the other known species in Papuafiliola by the dark brown pattern on femora, the shape of the femora, the shape of the gills, the degree of development of the thumb-like projection on segment II of the labial palp and the distribution of small unpaired dorsal protuberances on abdominal tergites I–V. This transfer marks the first record of Papuanatula in Australia and extends the known range of Papuafiliola beyond New Guinea. The occurrence of this lineage in northern Australia further supports biogeographical connections between New Guinea and Queensland, already recognized in other mayfly genera such as Caenis Stephens, 1835, Prosopistoma Latreille, 1833 and Labiobaetis Novikova & Kluge, 1987 / Pseudocloeon Klapálek,1905. With the new combination Platybaetis is restricted to the Oriental realm and is absent from Australasia.