Eurycorypha pseudovaria, 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 : 609-610

Eurycorypha pseudovaria ( Figs. 3 , 4b , 6 , 8d , and 11 )

The basic unit of the calling song of E. pseudovaria is a short echeme, consisting of three impulse groups of different durations and modulations with different silent intervals ( Fig. 4b ). The impulse groups probably represent syllables. The first had a duration of 23.1 ms (range, 15.9–31.5 ms; means of 7 males, each based on ≥ 10 measurements). It was separated from the next by an interval of 69.5 ms (range, 61.6–81.7 ms). The next group was shorter (13.4 ms; range, 11.2–16.2 ms), followed by a short interval of 13.7 ms (range, 7.5–19.6 ms) and a final soft group with a duration of 14.6 ms (range, 10.2–25.6 ms; Fig. 11a ). This echeme was answered by the female. Often immediately after this unit (with an interval of 220 ms; range, 154–319 ms; means of 6 males, n = 2–10 per male), and after a possible female response, a series (1–6) of two-part sounds followed, interpreted as soft opening and loud closing hemisyllables (syllable periods 62.3 ms; range, 43.5–72. 5 ms; Fig. 11b ). Several of such series could follow after one responded song at intervals of several seconds without repeating the calling song ( Fig. 8d ). In a few males, such syllable groups were also observed isolated without the preceding echeme and were very rarely (observed once) also answered by a female. The intervals between the male songs typically lasted many seconds and remained even in duets above 5 s.

The acoustical response of the female was registered 231 ± 13 ms (2 females; 10 measurements per female) after the beginning of the echeme ( Figs. 6 and 11 ). It mostly consisted of one to three loud and several soft impulses (mean duration 45 ms). Due to the low variation in the male song and the variability of the female response, a special trigger element in the male song could not be identified. During a long acoustical interaction (about 1 h) between a male and a female, the female produced also spontaneous sounds without any close relationship to the male song. Surprisingly the male responded to these sounds several times with a series of syllables (delay, 483 ± 174 ms; n = 6) as if it would have had sung itself ( Fig. 11e ). The males produced these series with the same delay also if the female had responded to another male ( Fig. 11c ). In some rarely observed acoustical male-male interactions, males produced syllable series in response to the echeme of a “leading” male at similar intervals as the female response ( Fig. 11f ; 557 ± 98 ms; n = 8). Occasionally, a male produced a relatively long series of impulses during the time of an expected female response or shortly before ( Fig. 11d ).

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. 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. 11 Oscillograms of song interactions in Eurycorypha pseudovaria. a–e Male-female duets, details. f Male-male inter- action (1.5 s sections). See text and discussion for details