Eurycorypha ligata, Hemp, 2017

Heller, Klaus-Gerhard & Hemp, Claudia, 2020, Hyperdiverse songs, duetting, and the roles of intra- and intersexual selection in the acoustic communication of the genus Eurycorypha (Orthoptera: Tettigonioidea, Phaneropterinae), Organisms Diversity & Evolution (New York, N. Y.) 20 (4), pp. 597-617 : 606-607

Eurycorypha ligata ( Figs. 3 , 4b , 5 , 6 , 8b , and 9b, c )

The calling song of E. ligata consists of elements in which three components were combined. An element typically started with a crescendoing series of short syllables (syllable period, 44.0 ± 6.4 ms; syllable number, 5.6 ± 1.9, n = 84), immediately followed by a syllable series with similar rhythm (syllable period, 46.1 ± 5.4 ms; syllable number, 5.4 ± 1.7, n = 61; SRR, 22 Hz), but much longer syllables ( Figs. 4b and 5 ). After an interval of about 200 ms (219 ± 52; n = 71) one very long syllable (80.3 ± 12.4 ms; n = 71) was added. This last syllable often consisted of a soft short first part (opening hemisyllable?) and a loud second part (closing hemisyllable?). The first syllable series was occasionally also produced without the following two parts. Besides these elements which were answered by the females, the males produced sometimes only isolated (intervals 10 s and larger) and quite loud pairs of syllables (syllable period, 61.8.1 ± 1.4 ms; syllable duration, 20.8 ± 1.31 ms; n = 10; SRR 16 Hz) for several minutes, or groups of about five loud syllables (pairs and groups not answered by females).

The females responded typically after the third part of the element ( Fig. 6 ). However, the long syllable at the end was obviously not necessary since several duets were recorded where this part was missing. The response occurred 328 ± 27 ms (n = 55; T = 23–25.5 °C) after the end of the second part of the group (lowest coefficient of variation compared with relation to the beginning of the group or to the end of the first series). Measured from the beginning of the long syllable (if present), the delay was 118 ± 26 and 50 ± 19 ms from its end. The influence of a female response on the intensity of the male song is difficult to document. It can be seen only in situations where the female starts to respond after a long silent period (see also Heller et al. 2020). Such a case is shown in Fig. 8b . After two loud pairs of syllables, the male started with a series of elements. After the first female response, it reduced its song intensity abruptly by about 14 dB, still sufficient to elicit a response, and continued with this reduced intensity, receiving responses.

In acoustical male-male interactions (without females), the first male produced regular sequences of syllable groups (60 and 150 s recorded), the second in one case series of ticks without clear relation to song of the first. In another case (to another male), the ticks of the second were timed similarly as female responses in 65% of the cases (13:20) ( Fig. 9 ).

Figures

Fig. 3 Power spectra of male calling song of Eurycorypha species. In species with restricted frequency range, short black lines mark its end. Blue lines indicate power spectra of female responses

Fig. 4 a, b Oscillograms of male calling songs, overview (10 s sections)

Fig. 5 Oscillograms of male calling songs, details (1.5 s sections)

Fig. 6 Oscillograms of male- female duets, overview (10 s sections)

Fig. 8 Oscillograms of long acoustical (1 min sections) interactions of a males in Eurycorypha curviflava and duets of males and females in b E. ligata, c E. pianofortis, and d E. pseudovaria

Fig. 9 Oscillograms of song interactions in Eurycorypha curviflava and E. ligata. a Male-female duet in E. curviflava, b, c Male-male interactions in E. ligata (6 s sections)