Dinarippiger discoidalis (Fieber, 1853) Skejo & Kasalo & Fontana & Ivković & Tvrtković & Rebrina & Adžić & Buzzetti & Ćato & Deranja & Gomboc & Scherini & Škorput & Veenvliet & Vuković & Lemonnier-Darcemont & Darcemont & Heller, 2023

Skejo, Josip, Kasalo, Niko, Fontana, Paolo, Ivković, Slobodan, Tvrtković, Nikola, Rebrina, Fran, Adžić, Karmela, Buzzetti, Filippo Maria, Ćato, Sebastian, Deranja, Maks, Gomboc, Stanislav, Scherini, Roberto, Škorput, Jadranka, Veenvliet, Paul, Vuković, Marijana, Lemonnier-Darcemont, Michèle, Darcemont, Christian & Heller, Klaus-Gerhard, 2023, Dinarippiger gen. nov. (Tettigoniidae: Bradyporinae: Ephippigerini), a new saddle bush-cricket genus for Ephippiger discoidalis Fieber, 1853 from the Dinaric karst, Zootaxa 5271 (1), pp. 49-90 : 63-66

Bioacoustics of Dinarippiger discoidalis comb. nov.

The song of Dinarippiger discoidalis comb. nov. was first described by Harz (1967) and later analyzed and visualized by several other scientists ( Keuper et al. 1988 a, 1988b, Heller 1988, Keuper 1989, Jatho et al. 1992, Jatho 1995, Massa et al. 2012). Our data corroborate the findings of the previous studies, showing that the song consists of echemes containing 3–7 (only very rarely 1–2) syllables ( Fig. 11A–D ). In structure, it is thus similar to the songs of Ephippiger species (see Jatho et al. 1992, Massa et al. 2012) but differs clearly from the songs of the European Uromenus species ( Heller et al. 2021). Each syllable has a distinct opening and closing hemisyllable made by a series of strongly dampened impulses. These short elements are produced by jumping of the scraper against the teeth of the stridulatory file (see Fig. 11D ) as is typical for Ephippigerini . The frequency spectrum of the song has its peak in the ultrasound, around 20 to 40 kHz ( Fig. 11E ; Keuper et al. 1988b). A relatively high syllable number per echeme should enable D. discoidalis comb. nov. females to discriminate against the mono- or disyllabic song of E. ephippiger when the species co-occur in the same habitat in Slovenia (see above), Croatia (see above), Bosnia & Herzegovina (Mikšić 1969) or Montenegro ( Ingrisch & Pavićević 2012). In the Ephippiger diurnus complex, syllable number per echeme is important for phonotactic female choice ( Ritchie 1991).

However, after a closer inspection of the temporal parameters of amplitude modulation (besides syllable number per echeme), an unexpectedly large variation has been observed ( Table 1 ), even when taking the effects of temperature into account. Our data are too limited for drawing conclusions but among-individual differences as large as the ones found within a single field recording ( Gomboc & Šegula 2014; #61) are quite surprising, despite the fact that animals in the sun may sing much faster than the ones in the shade.

The stridulatory structures are situated on the tegmina of both males and females. In the males, the stridulatory file is located on the underside of the left tegmen, whereas in the females it is situated diagonally on the upper side of the right tegmen ( Fig. 12A–D ). Correspondingly, the scraper is formed by the inner edge of the right tegmen in the male and of the left tegmen in the female. The right tegmen of the male carries a large glossy mirror cell. Stridulatory teeth are rather symmetrical ( Fig. 12E–F ) as can be expected for a species with loud opening and closing hemisyllables. In the female, the stridulatory structures may be used exclusively in a defensive context, a function already mentioned by Krauss (1878) for this species. Judging from the very limited data on the number of teeth in the male stridulatory file, differences among populations may exist (see Table 1 ).

Figures

FIGURE 11. Oscillograms (A–D) and power spectrum of the calling song of Dinarippiger discoidalis comb. nov. A) Rijeka (two males, second distant animal starting), B) Žuljana, C) Lovćen pass near Kotor, D) Oscillogram of stridulatory movement and song [synchronous registration of left tegmen movement and sound (upper line: upward deflection represents the opening, downward the closing; lower line: sound)] of two syllables from male calling song, Lovćen pass near Kotor. 1 = duration of opening hemisyllable, 2 = duration of closing hemisyllable, 3 = duration of a syllable, 4 = syllable period. E) Power spectrum of the male calling song.

FIGURE 12. Left and right tegmina of males (A, B) and females (C, D) of Dinarippiger discoidalis comb. nov. E) Male stridulatory file on the underside of the left tegmen. F) Details of male stridulatory teeth (CROATIA, Crikvenica, leg. D. & O. v. Helversen). Scale—1 mm (A–D), 100µm (E), 10µm (F).

Tables

TABLE 1. Bioacoustical data of D. discoidalis. T—temperature (°C); NSE—number of syllables per echeme; EP—echeme period [s]; DOH—duration opening hemisyllable [ms]; DCH—duration closing hemisyllable [ms]; DS—duration syllable (first to last impulse) [ms]; SP—syllable period (beginning penultimate to beginning last syllable) [ms]; SRR—syllable repetition rate; NI—number of impulses in (penultimate) closing syllable; IP—impulse period (mean of 10 in the middle of penultimate closing syllable); TN—tooth number.

Locality	T	NSE	EP	DOH	DCH	DS	SP	SRR	NI	IP	TN	Source
Italy (Trieste)	23	5	6.4 (n=9)	30	94	128	148	6.8	47	3.1	-	Massa et al. 2012. #2
Slovenia (Istria)	24	6	11.2 (n=3)	59	434	514	543	1.8	81	5.8	-	Gomboc & Šegula 2014. # 60
Slovenia (Vremščica)	24	4–6	4.3 (n=8)	46	143	199	237	4.2	43	5.3	-	Gomboc & Šegula 2014. # 61
Croatia (M. Učka)	?	4–5	3.9 (n=10)	36	105	149	185	5.4	43	3.1	-	Massa et al. 2012 #1
Croatia (Rijeka)	?	3–7	1–1.5	-	-	-	-	-	-	-	-	Harz 1967
Croatia (Rijeka)	25±2	3–7	-	23.6	92.2	125.7	149.6	6.7	39.5	-	83±6	Keuper et al. 1988, Jatho et al. 1993, Jatho 1995
Croatia (Rijeka)	20	4	-	32.5	183.5	229.5	245	4.1	63.5	3.85	-	this paper
Croatia (Rijeka)	24.5	4	-	51.5	342.5	408.5	435.5	2.3	65	6.4	-	this paper
Croatia (Rijeka)	23	3	-	53	235	306	335	3.0	-	-	-	this paper
Croatia (Pag)	?	2–4(5)	1–1.5	-	-	-	-		-	-	-	Duijm 1990
Croatia (Žuljana)	25	(1)4	-	25	239	284	312	3.2	43	5.7	-	this paper
Croatia (Hvar Isl.)	35	5–6	12.8 (n=4)	30	179	227	251	4.0	68	2.9	-	this paper
Montenegro (Kotor)	>28	4–7	4.2 (n=10)	18	73	99	116.5	8.6	32.5	2.9	113	this paper, Heller 1988
Montenegro (Golije Mt.)	26	2–3	3.5 (n=6)	22	203	238	260	3.8	-	-	-	this paper