Bioacoustics of Isophya miksici

Morphological description : Peshev 1985. Karyotype : Warchałowska-Śliwa et al. 2008 (as I. miksici and I. plevnensis ). Supplement to the description and a diagnosis : Body colouration fresh- or dark-green but not bluish. The disc of tegmina is yellowish-brown with dark stridulatory area. CuP is yellowish (similarly to I. andreevae , I. tosevski and I. clara and instead of greenish as in I. bureschi ), about 2/3 of the length of metazone. A tendence to bulging (uplifting) the disc of tegmina and its veins may be noted but the surface of disc is flat. The colouration of the lateral parts of tergites has a tendency for whitish opalescence. The stridulatory file ( Fig. 150 A, 151A) is short ( 2.5–2.9 mm ) with low number of teeth ( 65–88 in the Bulgarian population). Female stridulatory apparatus is shown in Fig. 151 C. Male cercus has a wide, short subapical tooth ( Fig. 150 B). The song ( Fig. 156 ) resembles that of I. andreevae but has shorter syllables with fewer impulses, and is almost identical to that of I. clara . Bioacoustics : Male calling song consists of groups of 3–6 syllables, the latter separated by an interval of 1–2 s (rarely up to 4 s) (Т=30°С). The syllables may have 1–3 after-clicks, usually apearing in the middle and final syllables of a group. The impulse period in the syllable is apparently longer among the first 5–8 impulses, gradually decreasing towards the end of the syllable. Sometimes the last 2–3 impulses again have distinctly longer periods. The song was investigated in two populations—from Vrachanska Planina Mt. (Stara Planina Mts) at 1000– 1200 m ( type locality) and the Iskar Valley near Iskar Town at ~ 50 m alt. At similar temperature (28–30°С) the song showed similar characteristics in the two populations. The syllables had 23–32 impulses (mean 27±3; n=40): in the mountain population the values are 23–31 (mean 27±2; n=20), in the lowland one—23–32 (mean 28±3; n=20). The length of the syllable (without after-clicks) was 112–213 ms (mean 166±25; n=40): in the mountain population—114–213 (mean 171±26; n=20), in the lowland one—112–197 (mean 162±24; n=20). Within the mountain population the after-clicks were more frequently observed (in 70% of the syllables) and the duration of the syllable+after-clicks became 285–516 ms, while the lowland population showed after-clicks in 20% of the cases and then the syllable became 247–319 ms. The impulse period frequently vary between individuals of the same population and may be from 5–6 ms (at the end) to 12–14 ms (at the beginning of the syllable). Rarely, the impulse period in the first 1–3 impulses reach 15 (in the mountain population)–20 ms (in the lowland population) and at the end the period decreases to 3 ms. The mean impulse period is 6.1 ms. Both populations showed some difference in the heterochromatin-content and B-chromosomes (supernumerary to the standard chromosome complement) were found in the mountain population (Warchałowska- Śliwa et al. 2008). Note : At this stage of knowledge the taxon is not well separated morphologically and bioacoustically from some populations of I. clara and I. plevnensis (see below) and some possibility for intraspecific relationships exists.