The assembly of a DNA barcode library for Australian Lepidoptera revealed that Oenochroma vinaria Guenée, 1858, as currently understood, is actually a mix of two different species. By analyzing DNA barcodes from recently collected specimens and the 150 year-old female lectotype of O. vinaria, we propose a reliable assignment of the name vinaria to one of these two species. A lectotype is designated for Monoctenia decora, a confirmed synonym of O. vinaria, and a new species, Oenochroma barcodificata sp. nov., is described. This species is only known from Tasmania and New South Wales; its biology and immature stages are described in detail.