1978] 
Morris & Gwynne — Cyphoderris 
159 
floor itself. The same is true of C. strepitans. Only C. monstrosa 
climb high into the trees as the night’s signalling progresses. At 
Monck Park singing heights in excess of 5 m were common and an 
hour after sunset collection without climbing trees becomes im- 
possible. 
The calling songs are generated by tegminal stridulation. As in 
Gryllidae the tegmina are morphological mirror-images, both left 
and right bearing a functional file and scraper. Unlike gryllids 
however, which maintain a characteristic ‘right above’ forewing 
overlap, the overlap of a Cyphoderris male may change during his 
lifetime and both files take part in his stridulation. 
Certain Tettigoniidae also have mirror-image tegmina and two 
functional files: Megatympanon speculatum Piza (Listroscelinae) 
(Riek, 1976), Neduba macneilli Rentz & Birchim, Neduba sierranus 
Rehn & Hebard (Decticinae) (Morris et al., 1975). Most tettigoniids 
have structurally distinct left and right forewings and overlap them 
‘left above’. In the Neduba species some individuals show left above, 
some right above. Unlike Cyphoderris they appear to maintain their 
particular overlap as individuals through life. Both overlaps were 
represented by Riek’s two (pinned) specimens of M. speculatum. 
Spooner (1973) analysed the calling song of C. monstrosa and 
describes it as a trill of grylloid (sinusoidal) pulses at a carrier 
frequency of 13 kHz. He noted substantial variation in the intensity 
and frequency of pulses and suggested that these changes “reflect 
irregular switching of tegmina from top to bottom position”. He 
refers to this habit as “switch-wing singing” and regards it as 
occurring several to many times in the course of a single trill. 
Overlap at rest (i.e. between singing bouts) is very infrequently 
changed in C. buckelli. The overlap of 16 individually-caged males 
was monitored by examining them once a day during almost 2 
weeks. Of 141 checks, only 4 reversals from the immediately 
previous overlap were observed; the incidence of resting overlap 
reversal was less than 3%. Thirteen of these males never showed an 
overlap reversal. 
Four C. monstrosa males checked over 5 days, gave similar 
results: two were never found with reversed overlap (checked 
respectively 5 and 6 times), one was reversed once in 5 checks and 
one twice in 6 checks. If Cyphoderris alter overlap several times 
within a single trill, it is strange that individuals end up so 
consistently at the same overlap with which they began. 
