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

Abstract

In Pamphagidae, the Krauss's organ is located on both sides of the 2 nd 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.

Phylogenomic analysis sheds light on the evolutionary pathways towards acoustic communication in Orthoptera

“…3). However, the ability of these structures to produce sound remains largely unconfirmed, except for a few species that use acoustic signalling for mating or defence 11,35,36 , and thus, we must consider them putative for now. Definitive sound-producing organs used for mating evolved at least three times in Caelifera (Fig.…”

“…1). Similar to the bladder grasshoppers, pamphagid grasshopper engage in pair formation via reciprocal dueting 78 , and males are often fully winged and females are flightless, although the loss of wings is quite common in this family 35 . Our study finds that Krauss's organ-femoral stridulation is a phylogenetically conserved mechanism of sound production for the family (Fig.…”

New distribution records of Orthoptera of Greece

“…This method of sound production is considered most primitive. The species of genus Paranocarodes Bolivar, 1916 have only a just visible Krauss's organ and no specialized hind femur (Massa 2012), thus have probably abandoned this mechanism, and have secondarily adapted a more evolved method of sound production (García et al 2014). The tympanum, a structure placed also on both sides of the abdominal tergites, although normally used for hearing only, in this case amplifies the emitted sounds.…”

“…The tympanum, a structure placed also on both sides of the abdominal tergites, although normally used for hearing only, in this case amplifies the emitted sounds. According to Massa (2012), members of Paranocarodes have a wide tympanum. Paranocarodes chopardi however does not seem to fit that rule as it has a very small tympanum (Ünal pers.…”

Revision of the genus Prionotropis Fieber, 1853 (Orthoptera: Pamphagidae: Thrinchinae)

“…Thrinchinae; 2) the inner side of the hind femora bear minute rounded tubercles that could rub on Krauss' organ (Krauss 1878, Saussure 1888); it was found in both P. hystrix and P. rhodanica, but it is a specialization of most Thrinchinae (Foucart 1995, Popov 1997, Ünal 2007a, Massa 2012; 3) a tegmino-alar stridulation has been described for P. rhodanica by Foucart (1995) and for P. appula , and probably occurs in other species of the genus and of the subfam. Thrinchinae, as well as in many species belonging to the subfam.…”