Structure and development of the auditory system in the prothoracic leg of the cricket Teleogryllus commodus (Walker) I. Adult structure

The microanatomy of the adult auditory system of the cricket, Teleogryllus commodus, is described with special attention to the number and arrangement of the groups of scolopidia forming the tympanal organ.

In the proximal part of the prothoracic tibia, there is a large posterior tympanum and a smaller anterior tympanum, which are associated internally with two expanded chambers of the tracheal system. The tympanal organ, which is identical in both sexes, is situated on the dorsal surface of the anterior tympanal trachea. It contains about 70 scolopidia, divided into two main groups: the proximal group, whose attachment cells insert on large accessory cells dorsally within the tympanal organ, and the distal group, whose attachment cells insert on modified dorsal hypodermal cells. These groups can be further divided into five main types, each containing a relatively constant number of scolopidia: 1. proximal group A; 2. proximal main group with proximal neurons; 3. proximal main group with distal neurons; 4. proximal part of distal group; 5. distal part of distal group. These types differ consistently in the following features: location of sensory neuron, orientation of dendrite and scolopale cell, structure of scolopale cell, shape and orientation of attachment cell and its connection to the secondary attachment cell.