Review of the genus Prochasma Warren (Geometridae, Ennominae, Boarmiini), with description of a new species from Hainan, South China

The few already published generic features of the genus Prochasma Warren, 1897 are reviewed and new-found characters are added to make the generic description more comprehensive. A new species, Prochasma diaoluoensis Liu & Stuning, <bold>sp. nov.</bold> is described from Hainan Province, China. It is the only Prochasma species found on this island and exceptional for its conspicuous pattern, vivid coloration and some morphological characters not observed in other species before. Descriptions and illustrations of adults, their venation, and male and female genitalia are presented. An identification key and an annotated checklist of all presently known species of Prochasma are provided. In addition, a DNA barcode sequence is given for the new species, and preliminary phylogenetic estimations of the genus Prochasma are discussed.