COMPLEX TIBIAL ORGANS IN FORELEGS, MIDLEGS, AND HINDLEGS OF THE BUSH-CRICKET GAMPSOCLEIS-GRATIOSA (TETTIGONIIDAE) - COMPARISON OF MORPHOLOGY OF THE ORGANS

The structure of the complex tibial organs in the fore-, mid-, and hin dlegs of the East Asian bushcricket Gampsocleis gratiosa (Tettigoniida e, Decticinae) is described comparatively. In each leg the tibial orga ns consist of three scolopale organs: the subgenual organ, the interme diate organ, and the crista acoustica. Only in the forelegs are the ti bial organs differentiated as tympanal organs, and sound transmitting structures (acoustic trachea, tympana, and tympanal covers) are presen t. The morphology of the tracheae in the mid- and hindlegs is signific antly different from that found in the forelegs. The number of scolopi dia 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 m idleg, 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 scolo pidia and the attachment structures within the crista acoustica of the mid- and hindlegs differ strongly from those in the foreleg. The resu lts 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 t he forelegs. (C) 1994 Wiley-Liss, Inc.