Bioacoustics of Isophya kraussii

Bioacoustics. Males produce a soft song (at least for the human ear) by tegmino–tegminal stridulation, consisting of a long sequence of syllables ( Fig. 4 a–d, i–l; table 2). A syllable is formed of a compact series of 80– 125 impulses, lasting for about 250–443 ms (up to 600 ms in recordings from Roesti & Keist 2009), followed after 41–183 ms by one (rarely 2–7) after–clicks (n=200 syllables from 9 males ). The relatively short syllables recorded in the song of some males from Jeseníky Mountains (N Morava) may be the effect of the high temperature (30°C) during recording (Kočárek 2005). The impulse interval is highly variable, 2–9 ms. The following syllable begins after 58–297 ms. During pair formation, females may respond acoustically to males with simple clicks (Heller 1990). Spectrographic sound analysis reveals frequencies between 20–40 kHz ( Fig. 4 q).

Description. Male. Head with fastigium verticis slightly tapering frontward, narrower than scapus, dorsal sulcus present ( Fig. 2 b). Pronotum saddle–like, disc constricted in the transverse sulcus area, with lateral carinae widen in metazona. Dorsal margin of paranota slightly concave, anterior edge straight, posterior and ventral margins moderately convex ( Figs. 2 b, d). Tegmina shorter than pronotum, angle between cubital veins is about 70°, length of Cu2 vein about 4/5–5/6 posterior border of pronotum, mirror large and quadrangular. At distal end of Cu2, the right margin of left tegmen forms an angle of about 90° ( Fig. 2 b). Stridulatory file length about 2.8–3.1 mm , counting 195–229 teeth ( Fig. 3 c, d). Cercus hairy, gradually narrowing towards tip, curved in apical 1/4. Terminal denticle triangular, positioned in middle of cercus apex; epiproct about 1.7 times as wide as long ( Fig. 2 f). Subgenital plate elongated and narrowed apically, with triangular apical shaped incision ( Fig. 2 h). Hind femur about 4.4–4.8 times pronotum length, without ventral spines ( Table 1 ). Coloration green, with fine dark green spots. In rare cases, males have two dorsal bilateral stripes from pronotum to end of abdomen, dark red or orange colored. Antennae greenish or reddish–brown, with light green scapus. Femora, tibiae and tarsi green, brownish or reddish. A white band begins behind the compound eye and ends at posterolateral area of tegmina. A brown band is present above the white one in metanotum. Tegmina brown, rarely dark green, apical area green and costal margin yellowish–white. Cerci brown or reddish–brown, rarely green. HW (mm) PL (mm) PW (mm) TL (mm) TW (mm) BL (mm) FL (mm) CL (mm) S O (mm) kraussii kraussii Isophya male (n=7) female (n=3) Max. Min. Mean S. D. Max. Min. Mean 3.3 3.13 3.24 0.08 3.72 3.31 3.57 4.18 3.9 4.01 0.12 4.51 4 4.25 4 3.81 3.90 0.09 4.35 3.5 3.94 3.59 3.44 3.5 0.07 1.91 1.35 1.68 3.97 3.75 3.88 0.10 3.23 2.9 3.11 23.9 19.3 21.57 1.39 23.4 19.71 21.7 15.39 14.55 15 0.43 16.4 15.09 15.66 2.39 2.27 2.32 0.06 1.29 1 1.15 274 296 287 8.79 – – – – – – – 11.88 9.32 10.69 S. D. 0.23 0.26 0.43 0.30 0.18 1.86 0.67 0.15 – 1.29 . n. ssp moldavica kraussii Isophya male (n=15) female (n=15) Max. Min. Mean S. D. Max. Min. Mean S. D. 3.69 3.27 3.49 0.12 4.1 3.85 3.94 0.07 3.92 3.3 3.63 0.19 4.76 4.29 4.49 0.15 3.96 3.85 3.89 0.03 4.25 4.14 4.19 0.03 3.56 3.33 3.43 0.07 1.98 1.5 1.73 0.14 3.72 3.57 3.64 0.05 3.4 3.11 3.23 0.09 25 22.3 23.62 0.70 24.95 23.3 24.15 0.44 17.8 15.9 16.66 0.55 17.55 16.8 17.15 0.22 2.74 2.24 2.42 0.13 1.35 1.19 1.25 0.06 229 195 201.93 8.15 – – – – – – – – 12.1 10.9 11.59 0.52 SD (ms) IP (ms) NI DAC (ms) NAC GS (ms) T (ºC) Isophya kraussii kraussii Min. (n=200 syllables, 9 males) Max. 250 443 2 62 9 134 41 1 183 7 58 297 21.5–27 Mean 313.97 4.48 96.97 92.27 1.43 140.27 S. D. 39.5 1.37 22.09 33.78 1.18 57.94 Isophya kraussii moldavica ssp. n. Min. (n=200 syllables, 30 males) Max. 89 200 2 30 4 58 60 1 113 3 69 292 17–26 Mean 114.96 3.08 48.24 89.26 1.09 171.74 S. D. 34.87 0.71 9.42 14.53 0.35 69.2 Female. Fastigium narrower than scapus ( Fig. 2 j). Pronotum with lateral carinae straight, disc marginally enlarged in posterior part and paranota slightly as in males, with ventral margin straight ( Figs. 2 j, l). Tegmina about 1/3 pronotum length, reaching the posterior margin of first abdominal tergite. Right tegmen with stridulatory bristles located on and near cubital veins ( Fig. 3 e). Cercus short, hairy, tapering; epiproct about 1.4 times as wide as long ( Fig. 2 n). Subgenital plate rounded, triangular, about 2.7 times as wide as long ( Fig. 2 p). Ovipositor 2.4–2.7 times pronotum length, upcurved, upper margin with 8–9 denticles and lower margin with 7–8 denticles ( Fig. 2 r). Hind femur 3.6–3.9 times pronotum length, without ventral spines ( Table 1 ). Coloration of body as in males, ovipositor green. Bioacoustics. Males produce their song usually at dusk and during the night, a long sequence of simple syllables. A syllable is formed of a compact series of 30–58 impulses, impulse interval 2–4 ms, and lasts for about 89–200 ms (n=200 syllables from 30 males ). Usually a syllable is followed after 60–113 ms by an after–click, rarely 2–3. The following syllable begins 69–292 ms later ( Figs. 4 e–h, m–p; table 2). Both parts (compact series of impulses and after-click) are the result of one closing stroke of tegmina. So far, we did not record any female acoustic response to male song. Sound frequency ranges from 15–20 kHz up to 40–45 kHz ( Fig. 4 r). Comparative note. Isophya kraussii moldavica ssp. n. differs from Isophya kraussii kraussii mainly in acoustics and less in morphology. The song of males from the Moldavian populations consists of shorter syllables, formed of 30–58 impulses (mean±SD: 48.24±9.42) and lasting for about 89–200 ms (mean±SD: 114.96±34.87), while males of the nominal subspecies produce longer syllables, formed of 80–125 impulses (mean±SD: 96.97±22.09) and lasting for about 250–443 ms (mean±SD: 313.97±39.5), sometimes up to 600 ms (Roesti & Keist 2009). After–clicks are produced in a similar time window in the 2 subspecies, after 60–113 (mean±SD: 89.26±14.53) in Moldavian individuals and after 41–183 (mean±SD: 92.27±33.78) in Central European specimens. Male stridulatory file is shorter and contains 195–229 teeth in I. kraussii moldavica ssp. n. , compared with 260– 305 teeth in I. kraussii kraussii . Some other minor morphological variations were noticed in the two subspecies: male wing with longer and triangular posterior lobes in I. kraussii kraussii and shorter and rounded lobes in I. kraussii moldavica ssp. n. , longer pronotum and wings in males of I. kraussii kraussii and stubbier cercus in males of I. kraussii moldavica ssp. n. Females of the new subspecies have somewhat longer ovipositor: 10.9–12.1 mm , compared with 9.32–11.88 mm in nominal subspecies.