New Stridulatory Structures in a Tiger Beetle (Coleoptera: Carabidae: Cicindelinae): Morphology and Sound Characterization

The stridulatory mechanism in Oxycheila tristis (Fabricius) (Cicindelinae: Megacephalini) is described. Sound is produced by males and females rubbing the internal edge of the hind femur (plectrum) on the ringed elytral epipleura (pars stridens). The hind legs usually alternate, and sound is mostly generated during backward movement. Abdominal movements seem to play a role in the amplitude modulation of the signals. Temporal characteristics of the sound are slightly different for both sexes (longer leg cycles in females) but the frequency spectra are similar. The same stridulatory structures were found in other Oxycheila species as well as in the closely related Cheiloxya binotata longipennis Horn. Considering the different stridulatory mechanisms described in cicindelids, sound production probably evolved independently at least three times in this group.