A new Australian genus of Orthotylinae, Myrtlemiris Cheng, Mututantri & Cassis gen.n., is described, with nine included species described as new to science (M. agnewsp.n., M. astartephilasp.n., M. meanarrasp.n., M. newmanensissp.n., M. rubrocuneatussp.n., M. russulatussp.n., M. silveiraesp.n., M. tesselatussp.n., M. yalgoosp.n.). A phylogenetic analysis based on 39 morphological characters is presented for all Myrtlemiris species and 6 outgroup taxa. This analysis establishes Myrtlemiris as monophyletic, defined by a broad apophysis on the left paramere. A key to species is provided and diagnostic characters are illustrated. Myrtlemiris is endemic to southwest Western Australia. Host plants for Myrtlemiris species are near restricted to the myrtaceous tribe Chamelaucieae.