Functional morphology and phylogenetic significance of the forewing base structure in Ensifera (Orthoptera)

The forewing base structure of the orthopteran suborder Ensifera, a group of insects well known for their sound-producing behavior, was examined by using light microscopy, confocal laser scanning microscopy, and µCT. We detected significant novel characters, such as functional changes in the tpm9 muscle from the flexor to the extensor of the forewing that are likely associated with the acquisition of sound-producing behavior using forewings. Phylogenetic analysis based on the characters selected from the forewing base structure showed that the character system contains a strong phylogenetic signal supporting the monophyly of Ensifera, Tettigonioidea and Grylloidea as well as the sister-group relationship between Grylloidea and Gryllotalpoidea, but no apomorphies to resolve the deep phylogeny among superfamilies could be determined from this character system.