The role of the Krauss’s organ in sound production in Pamphagidae (Caelifera: Orthoptera).

In Pamphagidae, the Krauss’s organ is located on both sides of the 2nd tergite and its function is superficially known. It has been proposed to have a stridulatory function. This organ can be found in all Pamphagidae except the apterous genera. Rearing specimens of some species and observing mounted pamphagids allowed the author to observe that when the Krauss’s organ is absent (most apterous species) the tympanum is also absent; further, he discovered specialized stridulatory structures on hind femurs of some taxa for sound emission. By rearing two Pamphagidae belonging to different genera, fragments of stridulations involving the Krauss’s organ and specialized structures on the hind femur surface were obtained for the first time. Mapping the presence of these morphological characters onto the known Pamphagidae list revealed that specialization on the hind femur surface evolved multiple times in multiple geographical locations in winged species with a wrinkled Krauss’s organ. The function of the sounds produced by the femur-Krauss’s organ method remains to be studied.