Evolution and systematics of Green Bush-crickets (Orthoptera: Tettigoniidae: Tettigonia) in the Western Palaearctic: testing concordance between molecular, acoustic, and morphological data

The genus Tettigonia includes 26 species distributed in the Palaearctic region. Though the Green Bush-crickets are widespread in Europe and common in a variety of habitats throughout the Palaearctic ecozone, the genus is still in need of scientific attention due to the presence of a multitude of poorly explored taxa. In the present study, we sought to clarify the evolutionary relationships of Green Bush-crickets and the composition of taxa occurring in the Western Palaearctic. Based on populations from 24 disjunct localities, the phylogeny of the group was estimated using sequences of the cytochrome oxidase subunit I (COI) and the internal transcribed spacers 1 and 2 (ITS1 and ITS2). Morphological and acoustic variation documented for the examined populations and taxa was interpreted in the context of phylogenetic relationships inferred from our genetic analyses. The trees generated in the present study supported the existence of three main lineages: “A”—composed of all sampled populations of Tettigonia viridissima and the Tettigonia vaucheriana complex, “B”—comprising Tettigonia caudata, Tettigonia uvarovi, and the Tettigonia armeniaca complex, and “C”—consisting of Tettigonia cantans. The present study provides the first phylogenetic foundation for reviewing the systematics of Tettigonia (currently classified mostly according to morphological characteristics), proposing seven new synonymies.