Bioacoustics of Isophya clara

Diagnosis. The new species is similar to I. modesta Frivaldsky, 1867 , which occurs in Romania . It differs in the male by shorter tegmina compared to pronotum length and by a lower number of teeth on the stridulatory file ( Tabs. 2–3 ). In the female it differs by a shorter and more strongly curved ovipositor. The difference in ovipositor length is distinct in females from Serbia (Beograd-Miljakovac), while in females from Durmitor, the ovipositor is of almost the same length as in I. modesta ( Tab. 2 ) but more strongly curved. Male stridulation is mono-syllabic with a single, uninterrupted pulse series, while in I. modesta the syllables consist of two pulse series separated by a short pause ( Orci & Heller 2004 ). I. modestior Brunner, 1882 , another widespread species on the Balkan peninsula, differs by stridulation, stridulatory file, shape and length of male tegmina and other morphometrical data ( Tabs. 2–3 ).

Description. A medium-sized to large species. Scapus 1.3–2.2 x broader than fastigium verticis. Fastigium verticis shallowly to deeply furrowed above. Male. Pronotum ( Figs. 3 A–B) widening posteriorly, lateral margins substraight to weakly concave, dorsal margin from almost straight to faintly raised before posterior margin. Tegmina 1.0–1.1 (mean = 1.07) times longer than pronotum; stridulatory vein (cu2) hardly thicker than the other veins. Stridulatory file ( Figs. 4 A– B) with 58–72 teeth of increasing size from base to internal margin of wing. Epiproct ( Fig. 3 D) transverse, apico-lateral angles rounded. Cerci ( Figs. 3 D–E) gradually narrowing towards apex, curved in circa apical third; apex transverse-truncate and with a minute tooth. Subgenital plate ( Fig. 3 D) narrowing before apex; apex with two triangular lobes. Female. Pronotum ( Fig. 3 C) slightly widening posteriorly, lateral and dorsal margins substraight. Pronotum 1.7–2.4 (mean 2.0) x longer than tegmina; apex of tegmina faintly convex. Epiproct rounded to transversely rounded. Cerci conical, apex subacute to subobtuse. Subgenital plate ( Fig. 3 F) small, transversetriangular. Ovipositor ( Fig. 3 G) sabre-shaped, weakly curved, apex dentate. species I. modesta Frivaldsky, 1867 and I. modestior Brunner v.W., 1882 [minimum-maximum (mean)]. Localities as in Tab. 2 . Species Index Pronotum Tegmen n Number of n Scapus: Fastigium length: width length: width stridulatory teeth Locality Syllable duration (ms) Number of pulses Temperature (˚C) n Coloration. Green with blackish brown dots. Two white lateral bands on vertex, discus of pronotum, and ventral margins of pronotum. Pronotum with two red stripes medial of the white band. Tegmina of male with a large medium brown spot on discus between Media and Cubitus2. I. modestior (SR) 3 1.60–2.50 (1.91) 0.93–1.09 (1.02) 0.82–1.01 (0.91) 23 150–254 (198) 15 I. modestior (SR) Ƥ 1.56–2.27 (1.85) 1.01–1.13 (1.07) 25 I. modestior (MG) 3 1.41–2.08 (1.66) 0.96–1.07 (1.02) 0.84–1.00 (0.93) 7 190 1 I. modestior (MG) Ƥ 1.79 1.01–1.11 (1.06) 2 I. modesta (RO) 3 1.69 1.09 1.30 1 95 1 I. modesta (RO) Ƥ 1.38–1.69 (1.55) 1.07–1.12 (1.10) 3 I. clara (MG) 3 1.33–1.75 (1.55) 0.93–1.08 (1.00) 1.03–1.15 (1.09) 11 70–72 (71) 2 I. clara (MG) Ƥ 1.50–1.82 (1.64) 1.04–1.14 (1.08) 5 I. clara (SR) 3 1.39–2.17 (1.81) 0.96–1.11 (1.04) 1.01–1.32 (1.18) 21 58–70 (63) 4 I. clara (SR) Ƥ 1.40–1.93 (1.69) 1.04–1.14 (1.09) 10 Donj Unaċ (Durmitor) 214-313 (262) 26-31 (29) 23 29 Trsa (Durmitor) 180-260 (224) 24-28 (26) 26 32 Trsa (Durmitor) 197-250 (232) 26-28 (27) 25 7 W. Dubrovsko (Durmitor) 128-166 (151) 23-25 (24) 27 9 W. Dubrovsko (Durmitor) 136-153 (146) 27-29 (28) 26 7 Boricje - Seljkovac (Durmitor) 153-238 (197) 25-31 (29) 26 13 Miljakovac (Belgrade) 163-199 (179) 23-27 (24) 25 17 Zlatibor 245-310 (281) 23-31 (26) 22.5 10 Pešter Plateau 174-250 (220) 21-27 (25) 25.5 21 Pešter Plateau 151-175 (165) Sopoċani 203-302 (239) 20-25 (23) 23-30 (27) 26.5 26 12 16 Zlatar 266-315 (292) 26-27 (27) 19 3 Zlatar 198-223 (216) 26 26 2 Variation. Specimens from Miljakovac (Belgrade) differ from the above description as follows: Slightly smaller ( Tab. 3 ). Index "length of tegmen: length of pronotum" more variable but with about the same mean (male 0.9–1.3, mean 1.02). Spot on male tegmen blackish brown. Epiproct in male from subquadrate to transverse, apico-lateral angles rounded and slightly concave in between. Subgenital plate in male with triangular apical lobes smaller. Cerci of female subobtuse to obtuse. Subgenital plate of female transversely rounded; in females from Zlatibor it is either rounded or triangular. Ovipositor shorter ( Tab. 2 ).

Distribution. Presently known from Montenegro and Serbia . Stridulation ( Fig. 5 ). The calling song consists of single, decrescenting syllables of 128–315 ms ( Figs. 5 A–B, Tab. 4 ), which are usually arranged in loose groups with a variable number of syllables. The number of pulses in a syllable is only 20–31, corresponding to the low number of 58–72 teeth on the stridulatory file ( Tab. 4 , Figs. 4 A–B). Those teeth are narrow at the base and gradually become spaced towards the internal margin of the wing. As the number of teeth is more than twice as much as the number of pulses in a syllable and each stroke of the scrapper at a teeth produces a pulse, that would mean that less than half of the teeth are used in sound production. The frequency range shows a distinct maximum at about 14–17 kHz. Thus the song is more clearly audible to the human ear than that of other Isophya species. The variation of the syllable duration depends mainly on temperature ( Fig. 5 C). The number of pulses do not differ markedly between different populations from Montenegro and Serbia ( Tab. 4 ).

Diagnosis : Ingrisch and Paviċeviċ (2010) diagnoze I. clara comparing it with I. modesta (and I. modestior — for differences see the latter paper), from which it clearly differs in song, consisting of groups of much shorter and uninterrupted syllables, pronotum and tegmen shape, number of stridulatory teeth, cercus tooth and ovipositor shape. However, in size, morphology (compare Figs 39 , 64 , 88 , 113 , 144 with 40, 65, 89, 114, 150, 151) and song (compare Ingrisch and Paviċeviċ 2010: Fig. 5 A, B with present paper, Fig. 156 ), this species much resembles I. miksici , from which it seems to be isolated by the river Morava in Serbia . At similar air temperature, the song of I. clara cannot be differentiated by that of I. miksici , either using syllable duration, number of impulses or impulse interval. Unfortunately, the description lacks exact data on the number of syllables in the groups and the syllables’ interval. I. clara may be differentiated by I. miksici on account of the pronotum shape (usually with more sinuately expanded metazone in I. miksici ), the relative size of the cercal tooth (larger and longer in “typical” I. clara ). The shape of tegmina in I. clara vary (see Ingrisch and Paviċeviċ 2010), which does not allow us to make comparison with other taxa and leaves the possibility of including more than one taxon within this species. This is especially true for the specimens from the region of Belgrade showing even bigger similarity with I. miksici .