Bioacoustics of Eurycorypha willschi

Bioacoustics . — In the male song, two different elements were observed. At first glance, both are quite similar (see Fig. 8 ), but they differ in SRR and function. Typically, several (to many) similar elements were repeated one after another. One of these elements invariably consists of pairs of syllables (Fig. 9 D ; syllable period 34–38 ms; means of three males , n = 10–18 per male; SRR 26–29 Hz; T = 20–23 ° C). The period of the pairs — called slow echemes — is quite variable (period 4–28 s; means of three males , n = 10–11 per male; range of measurements 2.7–65 s; T = 20–23 ° C). These slow echemes could be heard for relatively long times (up to 10 minutes recorded). More typically, however, a male switched to a series of the other element after a shorter time. This element consisted of 2–3 syllables (Fig. 9 E ; syllable period 20–22 ms; means of three males , n = 18–23 per male; T = 20–23 ° C), thus showing a clearly higher SRR (45–50 Hz); it is therefore called a fast echeme. Most of these series begin with elements of low amplitude and increase then in loudness (Fig. 11 C ). The females responded exclusively after these fast echemes. Their responses occurred 63–86 ms (means of three females , n = 10–12 per female; T = 20–23 ° C) after the beginning of the last (and loudest) syllable of the male echeme and 99–125 ms after the beginning of the first male syllable. Quite often the male added a series of very short syllables after the female’s response, occasionally even when the female had not answered. See discussion for the function of the parts of the song. The spectrum of the male song showed a broad peak around 16.5 kHz; that of the female was similar but even broader (Fig. 11 ; see Table 1 for other details). Male stridulatory file, tooth number, and inter-tooth intervals are in the range typical for Eurycorypha (Table 1 ; for comparison, see Heller and Hemp 2020 ).