A new species of skipper butterfly, Toxidia aurantia Braby, sp. nov., is illustrated, diagnosed and described from the northern Kimberley of Western Australia. A molecular phylogeny based on one mitochondrial (COX1 barcode fragment) and four nuclear genes (EF1-a, RSB2, RSB5, Wingless) for nearly all members of Toxidia Mabille, 1891 and its sister genus Timoconia Strand, 1909 according to the Maximum Likelihood optimality criterion, indicated that the new species belongs in the Toxidia xanthomera species-group (formerly classified in the genus Neohesperilla Waterhouse & Lyell, 1914) and is most closely related to T. crocea (Miskin, 1889). These two taxa are sister to T. xiphiphora (Lower, 1911). Toxidia aurantia Braby, sp. nov. is currently known from only a limited area on the mainland in the Admiralty Gulf near the Osborn Islands and Borda Island, WA. The discovery of this new species contributes to the emerging picture that the northern Kimberley is likely an area of high species richness for butterflies and day-flying moths within the Australian Monsoon Tropics.

Key words: Biogeography, butterfly, Ord Arid Intrusion, Trapezitinae, Victoria River Drainage Basin barrier.