Bioacoustics of Isophya modesta

Discussion. Only three specimens from Romania were available for comparison with a similar species from Serbia and Montenegro described below as I. clara sp. n. In general morphology both species are very similar but the tegmina are little longer as compared to the pronotum in I. modesta than in the latter species and the female ovipositor is longer and less curved (compare Figs 2 and 3 ). The male cerci are nearly identical. Stridulatory file and stridulation were recently described by Orci & Heller (2004) . The length of the file and the number of stridulatory teeth are of diagnostic value to tell apart I. modesta from I. clara , although the number of teeth in the male from Mehadia is only 95 ( Tab. 3 ) and thus quite lower than the number of 124 to 143 stridulatory teeth given by Orci & Heller (2004) for Hungarian and Transylvanian males. In I. clara from Montenegro and Serbia the number varies between 58 and 72. Measurements and some morphometrical data are summarised in Tabs. 2–3 .

Under this grouping we place most of the species of I. modesta group. Their distribution covers the Northern Balkan Peninsula (Northern Montenegro , Eastern Bosnia and Hercegovina , Northern Kosovo , Serbia , North Bulgaria , Romania , Hungary , Slovakia , Ukraine , reaching the region of Kursk in the southern European part of Russia . The complex is characterised by a large to very large body for the genus, with a massive habit. CuP vein is wide, frequently very bulged and long, except in I. miksici and I. clara , where it may be similar to that in I. bureschi ; in the other taxa it is>3/4 to almost equal to the width of metazone. Following west-east direction the disc of tegmina in the different taxa undergoes modification from greenish and slightly bulged to yellowish-brown and distinctly bulged (especially in I. longicaudata ). The stridulatory file bears between 55 and 160 teeth. The cercal tooth is pointed but short and wide contrary to the above described taxa. The song in taxa occurring in the western part of the range consists of groups of short syllables (similar to that of I. andreevae ) getting to the east consisted of single, long, almost compact (in I. longicaudata ) or split into two parts (in I. modesta ) syllables. After the revision made the complex includes 7 taxa of 5 species: I. clara , I. miksici , I. plevnensis sensu novo, I. longicaudata adamovici , I. longicaudata longicaudata , I. modesta modesta and I. modesta rossica .

Isophya modesta modesta (Frivaldszky) : Kis 1960. Isophya modesta intermedia Kis , syn.n. : Kis 1960 (ssp.n.). Morphological description : see the references above; Harz 1969; Heller et al. 2004. Bioacoustics : Orci and Heller 2004; Heller et al. 2004. Synonymy : Kis (1960) described I. modesta intermedia on the basis of slight morphological differences and different colouration of male tegmina recognising it from I. modesta modesta . At the time of this publication I. modesta was known from few localities in Central and Southwestern Romania and little was known on its morphological variation. Investigation of the song of typical I. m. intermedia showed it coincides with that of typical I. m. modesta . The measurements at 23°C were as follows: main part of syllables—56–170 ms with 15–26 impulses and impulse interval of 3–8 ms; second part—640–1340 ms with 25–42 impulses and impulse interval of 4(at the end)–127 ms. Both parts were separated by an interval of about 4–6 seconds and thus the total syllable duration was 5300–7460 ms. These characteristics fit well the measurements at higher temperatures given by Orci and Heller (2004) except the shorter main syllable part. However, regarding the great variability of the temporal song characteristics of I. m. modesta (compare Orci and Heller 2004) we consider I. m. intermedia a junior subjective synonym of I. m. modesta .

The group exhibits intermediate characters between these of I. rectipennis group and a number of more specialised (mostly) Central European species. The body is large to very large for the genus, moderately stout to massive. Hind femur is usually longer than 20 mm . The width of fastigium verticis is 1/2 to 3/4 of the width of scapus. The disc of pronotum is not saddle-shaped but frequently is considerably extended backwards and moderately raised in metazone. The sulcus dividing the pro- and metazone passes about the middle of pronotum. Male tegmina are elongated but the stridulatory part predominates. The tegmen is equal or up to about 1/3 times longer than pronotum. CuP is moderately to strongly widened and has variable length within the group; CuP and CuA are moderately to strongly attached (especially in I. longicaudata and I. rhodopensis petkovi ). The stridulatory file is well developed, wide and bears 55–180 teeth. Female tegmen has oval (as in I. rectipennis group) or slightly blunt apex and intermediate venation (parallel along its costal margin getting almost reticulate on its dorsal surface). The lower keels of hind femur have usually 1 spine each; rarely spines are not developed (in I. bureschi ). Male cercus is massive, characteristically angularly incurved at its apical third (compare Figs 84–96 ). The apex of cercus has a large subapically situated tooth, which may be conical or crest-shaped. Female ovipositor is always long for the genus, more than 2.3 times longer than pronotum, except in I. yaraligozi and I. tosevski , or rarely in I. rhodopensis petkovi ; the dorsal edge of the lower valve (lamella) rounds the gonangulum and forms a widely opened pit. The body colouration is greenish with or without dorsal light or pink bands. The lateral edges of pronotum have reddish to black coloured stripe situated only in the metazone over the light band. Melanism is always absent. The song consists of isolated or groups of syllables that may be compact or divided into main and additional part. The main part lasts from about 30 up to more than 1000 ms with the additional part becoming up to more than 10 s in I. modesta . The X-chromosome is subacrocentric ( type 2A or 2B according to Warchałowska-Śliwa et al. 2008; both types may occur within species complexes or even within a species). Herewith we consider the group with 14 taxa (10 species): I. andreevae , I. bureschi , I. yaraligozi , I. clara , I. longicaudata adamovici , I. longicaudata longicaudata , I. miksici , I. modesta modesta , I. modesta rossica , I. rhodopensis leonorae , stat.n. (= I. kisi , syn.n. ), I. rhodopensis rhodopensis , I. rhodopensis petkovi , stat.n., I. plevnensis (= I. pravdini pravdini , syn.n. ), I. tosevski . The taxon I. pravdini bazyluki is considered in another species group (see below). I. modesta group is distributed on the Balkan Peninsula (South to Northeastern Greece ) with one species reaching Central and Eastern Europe and an isolated distribution of I. yaraligozi in Norhwestern Anatolia . With the aim of revision and to present an overview of this complicated group we consider all of its taxa below.

Diagnosis : This subspecies was described by Bey-Bienko (1954) on the basis of subtle morphological differences (Orci and Heller 2004), including stronger CuP vein. It is hardly recognisable from the nominate subspecies both using morphology and male calling song. The only stable difference seems to be the timing of the female response to the male calling song (Orci and Heller 2004), yet, the song of I. m. modesta was compared only with older literature data (Zhantiev and Korsunovskaya 1986) for I. m. rossica and thus the differences observed may be due to incomplete data for the female answer gathered by Zhantiev and Korsunovskaya (1986). Therefore, the case may concern synonymy of I. m. rossica with the nominate subspecies.

Distribution and phenology : Known from Northeastern Ukraine and the neighbouring territory of Russia (the region of Kursk). Inhabits steppe associations and forest meadows in the lowland and hilly terrains. Nymphs—IV– VI, imago—VI–VIII. 3.5. Complex Isophya rhodopensis Four similar taxa were described from the Rila-Rhodope Mountain group in Bulgaria and Greece , which distinction is problematic (Chobanov 2009a) and which distributional ranges are unclear (e.g. Willemse and Willemse 2008: note on p. 18). These are I. rhodopensis , I. leonorae , I. kisi and I. petkovi . The transitions and great similarities between them in morphology, bioacoustics (see below), karyology (Warchałowska-Śliwa et al. 2008), as well as the intraspecific genetic variation (Grzywacz and Warchałowska-Śliwa 2008; Grzywacz-Gibała et al. 2010) does not allow their definitive distinction as species. Furthermore, a clinal transition in morphology and song characters was observed during the present study between different populations (mostly in West-East direction) resembling a case of ring species. However, the close approximation of the populations and the low differentiation, allows us to regard all the studied populations as belonging to one variable species with three subspecies.