MORPHOLOGY OF THE TIBIAL ORGANS OF ACRIDIDAE - COMPARISON OF SUBGENUAL AND DISTAL ORGANS IN FORELEGS, MIDLEGS, AND HINDLEGS OF SCHISTOCERCA-GREGARIA (ACRIDIDAE, CATANTOPINAE) AND LOCUSTA-MIGRATORIA (ACRIDIDAE,OEDIPODINAE)

The structure of the complex tibial organs in the fore-, mid-, and hin dlegs of two grasshopper species, Schistocerca gregaria (Acrididae, Ca tantopinae) and Locusta migratoria (Acrididae, Oedipodinae), is descri bed. In each leg the tibial organs consist of two scolopale organs: th e subgenual organ and the distal organ. Both organs are located in the hemolymph channel. The subgenual organ has a sail-like structure, and its scolopidia are oriented perpendicular to the long axis of the leg . The number of scolopidia in the subgenual organs is lower in Locusta migratoria than in Schistocerca gregaria. The scolopidia of the dista l organ are clearly separated from those of the subgenual organ and li e parallel with the long axis of the legs. They insert distally on an attachment plate that lies in the hemolymph channel. The subgenual org ans and the distal organs are smaller in the hindlegs than in the fore - and midlegs, and this difference is especially pronounced in Locusta migratoria. The complex tibial organ of Locusta and Schistocerca is v ery similar in structure and cellular composition with that of Peripla neta (Blattidae). In tettigoniids and gryllids the distal organ is dif ferentiated into an intermediate organ and the crista acoustica. (C) 1 995 Wiley-Liss, Inc.