Intra- and interspecific correlations between forewing morphology and sound production in six European bush cricket species (Tettigoniidae)

Bush crickets (Insecta, Orthoptera, Ensifera) stridulate with their forewings to produce acoustic communication signals, known as songs. Studies analysing the relation between the morphology of their specialised wing structures and the songs produced are usually performed either at the intraspecific or interspecific level. Here, the differences between intra- and interspecific analyses are shown by combining multiple statistical analyses on acoustic and morphometric data compiled from six European bush cricket species. The analysis shows an overall trend for negative correlations between the size of wing regions and the fundamental frequency of the song. On an interspecific level, the area of the mirror and harp on both wings are good predictors for frequency, with the area of the left wing mirror having the highest predictive power. However, results on the interspecific level are not found within all species. Likewise, correlations found on an intraspecific level cannot be interpolated onto all species. This is exemplified using the newly introduced morphological trait circularity of wing regions. Only in Phaneroptera nana does the circularity of the elongated right wing mirror show a significant correlation with the fundamental frequency. The results illustrate potential problems of generalisation, like the occlusion of species-specific adaptations and high intraspecific variation.