The above results support the conclusion that the majority of sound is radiated through the tympanal opening in typical cicada species, with the tyMPana being driven passively by the resonant vibrations of air in the air sac.
It is suggested that cicada sound production depends on the coupling of two resonators, that of the tymbal and the abdominal air sac, from which sound is radiated through the tympana, and that the abdomen of male cicadas forms a Helmholtz resonator.
From the morphological evidence, it is suggested that these chordotonal organs provide a very sensitive monitoring system for the activity of the sound producing apparatus.
The tymbal muscle of O. vanduzeei is indeed a synchronous muscle, albeit a highly modified one, capable of operating at 550 Hz, and it is suggested that the advantages of asynchronous muscles lie chiefly in their greater economy of structure and operation, rather than in an ability to operate at higher frequencies than synchronous muscles.
Tymbal muscles of the cicada Cyclochila australasiae Donovan are synchronous, those of Platypleura capitata (Oliv.) asynchronous, and they are used to illustrate the diagnostic features of synchronous and asynchronous muscles.
In the tettigoniid Neoconocephalus robustus, twitches from forewing muscles of male animals become progressively shorter over the first five days following the adult molt, indicating that neural input is necessary for this transformation.
The tympanal organ, the tracheal system and the tympana of Teleogryllus commodus is described, which develops in a proximo-distal direction but the more distal groups begin to form before the proximal groups are complete.
It is concluded that the auditory system of C. saundersii is finely adapted to the requirements of intraspecific acoustic communication with low frequency sound.
The tracheal organ of the mesothoracic tibia of Teleogryllus is located in a corresponding position to the tympanal organ and resembles the early nymphal trachesal system in both pro- and meso-thorcic legs.
SummaryThe 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…