Bioacoustics of Isophya rhodopensis

Morphological description : see the references above; Bey-Bienko 1954; Harz 1969 (as I. leonorae ); Ingrisch and Paviċeviċ 1985 (as I. leonorae ). Bioacoustics : Heller and Helversen 1986, Heller 1988 (as I. leonorae ). Karyotype : Warchałowska-Śliwa et al. 2008 (as I. kisi ). Synonymy : Peshev (1981) described I. kisi diagnosing it in comparison only with I. modesta . After comparing the morphology and calling song of diverse material from Bulgaria , including from the type locality of I. kisi , with these of I. leonorae , described from the neighbouring territory of Greece , it appeared obvious that both taxa are identical (first mentioned by Klaus-Gerhard Heller, personal communication). Thus, the preference was given for the senior synonym. Further, the morphology of I. leonorae from different localities shows great similarity to that of I. rhodopensis . The song of some populations from the western part of Western Rhodope Mts, located between the ranges of typical I. leonorae and I. rhodopensis (see below), has a structure closer to that of I. leonorae , though their morphology and karyotype characteristics may be intermediate between these of I. leonorae and I. rhodopensis or strongly remaining one of the latter taxa. These cases, we believe, concern hybrid populations, and therefore I. leonorae is here regarded as a subspecies of I. rhodopensis . Supplement to the description and diagnosis : I. rhodopensis leonorae has a large, stout body. The tegmen is very wide with long CuP and stridulatory file ( 3.8–4.2 mm ) bearing many teeth (149–170) ( Figs 45 , 162 A, 163A). Main colouration of male tegmen is green. The lateral stripes of metazone (above the light bands) are wide, reddish (compare with the other subspecies). Female stridulatory apparatus is shown in Figs 162 C, 163C. Typical characteristic of this subspecies is the very wide, showel-shaped apical tooth of male cerci ( Figs 162 B, 163B), usually narrower or pointed in the other subspecies. The song ( Fig. 168 ) consists of loose groups of decrescending syllables lasting 100–200 ms and sometimes followed by 1–2 after-clicks. Bioacoustics : The song in the typical population from Alibotoush (Slavyanka) Mountain at 25–26°С included groups of few (usually 4–10, rarely 2–3) or many (over 15) syllables, which were divided by an interval of 1.3–2 s. The syllables were short—116–176 ms (mean 151±17; n=20), consisted of 60–66 impulses (mean 65±3; n=20), and sometimes followed by 1 (rarely 2) after-click (thus the whole length of the syllable became 246–376 ms; mean 300±53; n=13). The impulses within the main part of the syllable were dense and the impulse period lasted from 2 to 6 (at the syllable’s end) ms (mean 2.3).

Isophya petkovi Peshev , syn.n. as ssp. : Peshev 1959a (sp.n.). Isophya leonorae Kaltenbach , syn.n. as ssp. : Kaltenbach 1965 (sp.n.). Isophya kisi Peshev , syn.n. : Peshev 1981 (sp.n.). Morphological description : see the references above; Bey-Bienko 1954; Harz 1969 (as I. rhodopensis , I. petkovi and I. leonorae ); Ingrisch and Paviċeviċ 1985 (as I. leonorae ). Karyotype : Warchałowska-Śliwa et al. 2008 (as I. rhodopensis , I. petkovi , I. kisi ). Synonymy : see below. Supplement to the description and a diagnosis : The body is large, stout, ventral keels of hind femora bear 1–2 small spines (rarely spines lack). The body colouration is fresh green, sometimes with two dorsal bands of white, pink or yellowish colour. Male tegmina are wide, longer or equal to the pronotum length, not distinctly bulged; their disc may be greenish (in the western and mountain populations) or yellowish-brown (in the eastern and lowland populations) with dark stridulatory area. CuP is thick, long (>3/4 of the width of metazone), greenish or yellowish coloured. In I. petkovi CuP may be distinctly approached to CuA. The stridulatory file has large number (130–180) of densely packed teeth. The cercus tooth is very typical—long, very wide, frequently crest shaped; the apex of cerci has dense strong hairs. The song consists of groups of two to many (>20) syllables (rarely single syllables occur) with a long syllable interval. The syllable (main part) has dense decrescending impulses and lasts 50–300 ms. Sometimes or, in some populations/taxa always, the syllables are followed by one or few after-clicks. The heterochromatin content of the chromosomes, especially X, is highly variable (Warchałowska-Śliwa et al. 2008). The species is distributed in the central part of Southern Bulgaria and the neighbouring territory of Greece on the territory of the Rila-Rhodope Mountain group (see below). Notes to the literature distribution data : The data by Nedelkov (1908) for I. modesta from “Rodopi” is tentatively referred to I. rhodopensis . And though the case may concern I. bureschi , usually Nedelkov has determined his material of I. bureschi as I. modestior , also mentioned from “Rodopi”. Thus, we believe Nedelkov had been working with material of both species occurring sympatrically in the Northwestern Rhodope Mts. The record by Paviċeviċ (1983a) for I. rhodopensis from Beljanica Mt. was referred to I. miksici (see above).

Description : The populations from the southwestern part of the Western Rhodope Mountains (Trigrad Village in Bulgaria and neighbouring Zagradenia forest in Greece ) show morphology of I. rhodopensis leonorae with some transitions to the nominate subspecies, mostly in the narrower male tegmen and less widened cercal tooth. Other populations from the central part of Western Rhodope, though morphologically belonging to the typical I. rhodopensis , showed a song ( Fig. 169 ) of very short syllables without after-clicks, thus similar to these of I. rh. leonorae (compare with Fig. 168 C). In few individuals from Shiroka Polyana Lake and Stoykite Village the syllables (in groups of 4–5; Т=27°С) were strongly shortened (even shorter than in I. rh. leonorae ), lasted 50–107 ms (mean 71±17, n=15), and consisted of 25–48 dense impulses (mean 36±8; n=15; their separation is frequently very difficult) with an impulse period of 2–4 (to 5) ms (mean 1.9).

Morphological description : Ramme 1951; Bey-Bienko 1954; Harz 1969. Karyotype : Warchałowska-Śliwa et al. 2008 (as I. rhodopensis and I. petkovi —partim: cf. localities). Supplement to the description and diagnosis : The body size varies. It is usually slightly smaller than in I. rh. leonorae , male tegmina are narrower and the stridulatory file is usually shorter— 2.9–3.7 mm with 134–155 teeth ( Figs 164–166 A), but in the lowland population from the region of Assenovgrad, intermediate to I. rh. petkovi , the file is up to 4.1 mm with 180 teeth. Main colouration of the disc of tegmina is green, rarely (in lowland populations) mixed with yellow. The lateral stripes of metazone are narrower than in leonorae and darker—reddish to blackish-brown. Female stridulatory apparatus is shown in Figs 164–166 C. Male cercal tooth ( Figs 164–166 B) is long and wide, usually more or less pointed but sometimes as in leonorae . According to its shape we could discern two forms— typical form with a wide cercus tooth similar to that of leonorae and Northwestern form with pointed tooth and song temporarily similar to that of I. rh. petkovi . The song ( Figs 170–172 ) consists of groups of 3–5 or more syllables. The syllables last 100–200 ms with 40–70 impulses and an impulse period of 2–7 ms. In all cases the syllable (main part) was followed by 1–5 after-clicks, thus the whole length (syllable+after-clicks) becomes 275–386 ms (27°С) to 800 ms (23°С). Bioacoustics : Typical form . The structure of syllables vary to some extent between different populations. Specimens from Smolyan (close to the type locality of I. rhodopensis in the Central Rhodope Mts) and the neighbouring Turun Village showed the following characteristics at 27°С. Smolyan ( Fig. 171 ): syllables—main part 142–160 ms (mean 152±6; n=10) with 43–55 impulses (mean 49±4; n=10) and impulse period of 2–6 ms (mean 3.2); Turun ( Fig. 172 ): syllables—main part 105–116 ms (mean 110±3; n=10) wtih 50–55 impulses (mean 52±2; n=10) and impulse period of 2–5 ms (mean 2.1). The animals from the northern slopes of Western Rhodope are morphologically and bioacoustically transitional to I. rh. petkovi in larger body, higher number of stridulatory teeth and development of black lateral stripes in metazone (compare below). The song of specimens from Assenovgrad and Bachkovo Village area at 23°С had longer interval between the main syllable part and the after-clicks, which is at least partly due to lower body temperature (but the main syllable part was even shorter). It had the following characteristics: syllables—main part 133–153 ms (mean 143±6; n=10) with 60–67 impulses (mean 63±2; n=10) and impulse period of 2–4 ms (mean 2.3) and a total duration with the after-clicks 714–762 ms (mean 739±16; n=8). Interestingly, here after-clicks were observed in all cases. Northwestern form . Specimens from the region of Batak Lake (NW Rhodope), Krichim, Pazardzhik (W Thrace Lowland) and Sushtinska Sredna Gora Mountain showed stable difference in the shape of the cercal tooth ( Fig. 165 B) being narrower and pointed, similar to that of I. andreevae . The song ( Fig. 170 ) does not differ significantly from that of the typical form but the syllables are longer with more impulses: syllables—main part 164–194 ms (mean 185±8; n=10) with 63–68 impulses (mean 66±2; n=10) and impulse period of 2–4 ms (to 7 ms at the end of the main part) (mean 2.8) (T=28°С). The populations from different regions show significant variation in the distribution of heterochromatine (Warchałowska-Śliwa et al. 2008) and are genetically variable (Grzywacz and Warchałowska-Śliwa 2008; Grzywacz-Gibała et al. 2010).

Distribution ( Fig. 193 ) and phenology : Distributed in the Eastern Rhodope Mountains ( Bulgaria and Greece— Kallithea by Willemse and Willemse 2008 as I. rhodopensis ; new for Greece ), Sakar ( Bulgaria ) and the neighbouring lowlands between 50 and 1200 m . No doubt this taxon has a restricted occurrence also in the northeasternmost corner of European Turkey . Nymphs—(?II–)III–V(–VI), imago—V–VI(–VII). 4. Isophya costata species group The group shows more specialised characters than I. modesta group and may have evolved from it or both groups have common origin. The body is moderately large to large. Hind femur is 16–23 mm long (usually 17–20). The width of fastigium verticis is 1/2 to equal to that of scapus. The disc of male pronotum is elongated, slightly to strongly widened in metazone, flat or moderately raised in metazone. Male tegmina are equal to or shorter than pronotum, frequently bulged, with shortened Costo-Medial part and compact, widened stridulatory area. CuP is moderately (in I. stysi Cejchan, 1958 ) to (usually) very long (>3/4-4/5 times of the hind margin of metazone) and wide (wider than 3rd or even 2nd antennal limb); CuP is moderately bulged, much wider than CuA; both are situated at about the same level over the pronotal surface (or CuA is slightly higher) and are closely approximated to each other. The stridulatory file has 50–275 teeth. Female tegmen has blunt to truncated (rarely slightly concave) hind margin and reticulate venation. Hind femur may lack or have from 1–2 to over 10 ventral spines. The pit between gonangulum and lamella is partly closed, the lamella is thin, without an excision. The ovipositor is moderately to very long for the genus (2 to over 3 times longer than pronotum). The main colouration is green (sometimes with light bands or variegated in I. dobrogensis ). Tegmina are usually greenish, sometimes with darkened stridulatory area. The lateral margins of pronotum in metazone have reddish stripe above the light band. Melanism is absent. The song (when known) consists of single or groups of syllables lasting 140–1100 ms. The X-chromosome of I. modestior may be acrocentric or subacrocentric ( type 1A or 2A according to Warchałowska-Śliwa et al. 2008 and unpublished data) in different populations (see below). Morphological traits of most taxa such as short and wide male tegmina and position of CuA and CuP, blunt female tegmina, high number of stridulatory teeth and shape of cerci indicate close relationships with the I. kraussii group. Presently we consider the group with six species— I. boldyrevi Miram, 1938 , I. costata Brunner von Wattenwyl, 1878, I. dobrogensis , I. modestior , I. stepposa Bey-Bienko, 1954, I. stysi Cejchan, 1958 , distributed in the Northern Balkan Peninsula, Central Europe ( Austria , Hungary , NE Italy ), the Carpathian Basin and Eastern Europe through the steppe belt eastwards to Volga Upland (Privolzhskaya vozvyshennost) in the region of Saratov.

Morphological description : Peshev 1959a. Karyotype : Warchałowska-Śliwa et al. 2008 (as I. petkovi —partim: cf. localities). Supplement to the description and diagnosis : The subspecies is characterised by a massive body and very large size for the genus (similar to I. taurica and I. longicaudata ). Male tegmina are visibly shortened (shorter than in I. rh. rhodopensis and I. rh. leonorae ) with stronger approximation of CuP and CuA. The stridulatory file is 3.5–3.7 mm long with 140–160 teeth ( Fig. 167 A). The disc of tegmina (before and after the dark stridulatory area) is yellowish-brown. The lateral stripes of metazone are blackish. Female stridulatory apparatus is shown in Fig. 167 C. Male cercus tooth ( Fig. 167 B) is similar to that of I. rh. rhodopensis . The song ( Fig. 173 ) consists of groups of few (2–6) syllables with few after-clicks (2–8, rarely one), whose number is higher when the temperature is lower. The impulses of the main syllable part are clearly separated and the impulse period at 20–22°С reaches 14– 18 ms at the beginning and again 10–12 ms at the end of the main part. The impulse period within the additional part (after-clicks) is 50–200 ms. Bioacoustics : The temporal characteristics of the male calling song vary at different temperatures. At 20°С: syllables—main part 261–292 ms (mean 277±11; n=10) with 54–68 impulses (mean 61±5; n=10) and impulse period of 3–18 ms (mean 4.5); total duration of the syllable with 5–8 after clicks— 1447–2039 ms (mean 1784±173; n=10). At 27.5°С: syllables—main part 166–192 ms (mean 179±8; n=10) with 64–72 impulses (mean 69±2; n=10) and mean impulse period of 2.6 ms; total syllable duration with 1–2 after-clicks—560–708 ms (mean 630±51; n=10).