FIGURE 23. Xeropsalta aridula n in Two new genera and five new species of Mugadina - like small grass cicadas (Hemiptera: Cicadidae: Cicadettini) from Central and Eastern Australia: comparative morphology, songs, behaviour and distributions

FIGURE 23. Xeropsalta aridula n. sp. Time expanded waveforms and complimentary envelope plots of two selected segments of echemes. Figs. 23 A, B, recording near start of an echeme, showing the details of four macrosyllables, these each characterised by high amplitude pulses emitted at the end of each macrosyllable. Although each macrosyllable has six higher amplitude main pulses, the pulses show a marked tendency to occur in sets of 4 or 3 pulses. The initial smaller pulse of each macrosyllable is followed closely by a gap (0.8–0.9 ms) and then a set of 4 pulses. These pulse patterns are inferred to result from a slight offset (asynchrony) of pulse emissions between the two timbals, resulting in partial pulse overlaps and the grouping of pulses into 4 or 3 sets, the start of each macrosyllable is marked by 3 partially merged pulses. These 3-pulse sets are inferred to result from the complete overlap of a second peak with the following first peak, resulting in the higher amplitude central peaks. Figs. 23C, D are cage recordings, in which at the end of echemes, the normal 2-timbal song is modified by the cessation of one timbal, causing a drop of the RR of the pulse doublets by half. In these 1 timbal segments, the doublet pulses show the initial high amplitude pulse and following low amplitude peak (0.8–0.9 ms offset). One interpretation is therefore that the initial strong peak results from the timbal rib 1, the weaker peak from the flexing of ribs 2 to 5. The alternate explanation is that the second weaker peaks are the secondary relaxation 'OUT' pulses. Filtered A, B, to 1 kHz. C, D unfiltered.