Structure of atympanate tibial organs in legs of the cave-living ensifera, Troglophilus neglectus (Gryllacridoidea, Raphidophoridae).

Troglophilus neglectus (Gryllacridoidea, Raphidophoridae) is a nocturnal Ensifera which can be found in caves of Slovenia. The anatomy of the tibial organs in the fore-, mid-, and hindlegs, as well as the external morphology of the proximal fore-tibia and the prothoracic tracheal system, is described comparatively. In the prothorax and in the forelegs, no sound-conducting structures such as an acoustic trachea, enlarged spiracles, or tympana are developed. A group of 8-10 campaniform sensillae is located in the dorsal cuticle of the proximal tibia. In each leg, the tibial organ complex is built up by two scolopale organs, the subgenual organ and the intermediate organ; the structure and the number of scolopidia is similar in each leg. No structure resembling the crista acoustica is found. The subgenual organ contains around 30 scolopidia; the intermediate organ is subdivided into a proximal part containing 8-9 scolopidia and a distal part with 5-6 scolopidia. The two groups of scolopidia are not directly connected to the tracheal system. The tibial organs in the forelegs are insensitive to airborne sound, and they appear to be more primitive compared to those found in members of the Tettigoniidae and the Gwllidae. The results indicate that the complex tibial organs in all legs of T. neglectus are primarily vibrosensitive. © 1995 Wiley-Liss, Inc.