Complex tibial organs in fore-, mid-, and hindlegs of the bushcricket Gampsocleis gratiosa (Tettigoniidae): Comparison of morphology of the organs.

The structure of the complex tibial organs in the fore-, mid-, and hindlegs of the East Asian bushcricket Gampsocleis gratiosa (Tettigoniidae, Decticinae) is described comparatively. In each leg the tibial organs consist of three scolopale organs: the subgenual organ, the intermediate organ, and the crista acoustica. Only in the forelegs are the tibial organs differentiated as tympanal organs, and sound transmitting structures (acoustic trachea, tympana, and tympanal covers) are present. The morphology of the tracheae in the mid- and hindlegs is significantly different from that found in the forelegs. The number of scolopidia in the subgenual organ is highest in the midleg and lowest in the foreleg; in the intermediate organ the number is also highest in the midleg, and the fore- and hindleg contain 40% fewer scolopidia. In the crista acoustica, the number of scolopidia decreases from, the fore- to the mid- and hindlegs. The morphology and the dimensions of the scolopidia and the attachment structures within the crista acoustica of the mid- and hindlegs differ strongly from those in the foreleg. The results indicate that, in addition to the presence of a sound transmitting system, the specific differentiations within the crista acoustica are important for the high auditory sensitivity of the tibial organs in the forelegs. © 1994 Wiley-Liss, Inc.