The dictyopharid planthopper genus Miasa Distant, 1906 (Orthopagini) is revised to include three known species, M. producta (Lethierry, 1888), M. smaragdilinea (Walker, 1857), and M. wallacei Muir, 1923, and two new species M. borneensis sp.n. and M. nigromaculata sp.n., all distributed in Southeast Asia. The confusion regarding the taxonomy of Miasa species is clarified on the basis of a critical review and examination of historical material. Male genitalia of all species and fifth-instar nymph of M. smaragdilinea are described and illustrated for the first time. A new genus Indomiasa gen.n. which is closely related to Miasa, is also established for a single new species, I. distanti sp.n., from southern India. A phylogenetic analysis based on morphological characters of adults was conducted to reconstruct the species-level phylogenetic relationships of Miasa and Indomiasa. The results show that the monophyly of Miasa and Miasa + Indomiasa is well supported. Keys to the genera of Orthopagini in the Oriental region and to the species of Miasa are provided.

New species, redescription, male genitalia, fifth-instar nymph, phylogeny, biogeography, taxonomy