Chorthippus kegenicus Vedenina & Tishechkin, 2025

Vedenina, Varvara, Tishechkin, Dmitry, Kovalyova, Evgenia & Sevastianov, Nikita, 2025, A new species of the subgenus Chorthippus Fieber, 1852 (Orthoptera: Acrididae: Gomphocerinae: Chorthippus) from Kazakhstan and Kyrgyzstan, closely related to C. angulatus Tarbinsky and C. karelini (Uvarov), Zootaxa 5653 (2), pp. 246-262 : 255-259

Chorthippus kegenicus Vedenina & Tishechkin sp. nov.

Material examined: Holotype ♂: 9 Kazakhstan , Almaty region , Kegen district, ab. 4 km SE of Kegen, flood-lands of Kegen river, N 42°59.65’, E 79°16.47’, 1824 m a.s.l., 07.07.2016, leg. V. Vedenina & T. Pushkar ( ZIN) . Paratypes: same locality and date as holotype, 1♂, 1♀ , leg. V. Vedenina & T. Pushkar ( ZIN), song recordings in 1♂ ; same locality as holotype, 20.06.2023, collected as larvae, 8 ♂, 11♀ , leg. V. Vedenina, N. Sevastianov & T. Tarasova ( ZIN, CV), song recordings in 7♂ ; 10 Kazakhstan , Jetisu region, Panfilov district, ab. 6 km SW of Zharkent, N 44°08.431’, E 79°55.325’, 594 m a.s.l., 06.07.2016, 7♂, 2♀ , leg. V. Vedenina & T. Pushkar ( CV), song recordings in 3♂ ; same locality, 21.06.2023, 6♂, 6♀ , leg. V. Vedenina, N. Sevastianov & T. Tarasova ( CV); 11 Kazakhstan , Almaty region , Raiymbek district, environs of Tuyuq, N 43°06.116’, E 79°24.538’, 1925 m a.s.l., 21.06.2023, 3♂ , leg. V. Vedenina, N. Sevastianov & T. Tarasova ( CV), song recordings in 3♂ . Kyrgyzstan: 12 southern beach of Issyk-Kul’, Tossor river mouth, N 42.175°, E 77.395°, 16.07.2013, 2♂, leg. D. Tishechkin ( FSCB) , song recordings in 2♂; 30.06.2024, 20♂, 3♀, leg. D. Tishechkin ( ZMMU) , song recordings in 4♂.

Other material, excluded from type series: Turkestanskii krai, earlier than 1918, 1♂ ( ZMMU) ; Kyrgyzstan: Issyk-Kul’ , 17 km N of Przheval’sk, 02.08.1953, 2♂, 2♀, leg. D. Panfilov ( ZMMU) ; environs of Issyk-Kul’ , canyon Arashan, 17.08.1990, 2♂, leg. S. Dialektov ( CV) .

Description. Head from above as wide as pronotum, 0.82–0.85 times as short as pronotum ( Fig. 7 G, H ). Foveolae distinct, visible from above, 2.8–3.75 times as long as broad. Antennae filiform, in ♂ extend slightly beyond hind coxa, in ♀ hardly reach hind margin of pronotum, its longest medial segments 2–2.6 times as long as wide. Pronotum with almost parallel lateral carina, ratio of max/min widths of pronotum less than 1.4; prozona nearly as long as metazona. Radial vein of tegmen clearly sinuate ( Fig. 7 E, F ). Stigma well developed. Tegmina projecting slightly beyond apices of hind knees. Tegmen in ♂ 4.5, in ♀ 5.1 times as long as wide on average. Alae slightly shorter than tegmina. The number of stridulatory pegs on the inner side of hind femur varies from 95 to 130 in ♂, from 89 to 117 in ♀. In the proximal part of the stridulatory file, the pegs arranged in a sinuous row very densely in ♂ ( Fig. 4 G ). The stridulatory pegs well-developed in both sexes. Tympanal organ in ♂ 2.3 times, in ♀ 2.8 times as long as wide on average. Cerci conical, in ♂ reaching margin of supra-anal plate, in ♀ reaching half of supra-anal plate. Subgenital plate in ♂ bluntly conical. Ovipositor short, without lateral teeth. Hind femur in ♂ 4.7, in ♀ 5 times as long as its maximum width on average. General colour brown, green forms not observed. Antennae of general colour, ventral side of apical segments commonly darker brown, particularly in ♂. Pronotum of general colour, in ♂ dorsum sometimes slightly darker, in ♀ lateral keels ventrally often bordered with dark sepia brown streak and exceptionally also with dark brown median keel. Tegmen in ♂ of general colour, in ♀ commonly costal area with white stripe, contrasting with darker brown Sc and often also R vein and sometimes darker brown coloured subcostal, medial and basal part of radial fields. Hind femur of general colour, in ♂ outer and particularly upper side or keels often darker brown towards the hind knee, in ♀ much less obvious. Hind knee in ♂ darker brown, especially upper lobe, in ♀ of general colour and often upper lobe only darker. Hind tibia of general colour, ventral side often dark brown, particularly towards the apex, more obvious in ♂. Hind feet of general colour, in ♂ often slightly paler, particularly third tarsus but not white.

Measurements (in mm). Body length ♂ 15–18, ♀ 20–24; pronotum length ♂ 2.9–3.5, ♀ 3.6–4.9; tegmen length ♂ 9.5–12.4 ♀ 11.6–15.5; tegmen width ♂ 2.1–2.8, ♀ 2.2–2.9; femur length ♂ 8.3–10.2; ♀ 10.6–14.2; femur width ♂ 1.8–2.2, ♀ 2.1–2.8; peg number in ♂ 95–130, in ♀ 89–117.

Etymology. This species is named from the type locality in the environs of the Kegen village, in the flood-land of the Kegen river.

Morphology. The new species can be distinguished from C. karelini by the significantly smaller number of stridulatory pegs: the peg number varies from 95 to 130 in the C. kegenicus males, whereas the peg number varies from 140 to 188 in the C. karelini males. Moreover, the proximal pegs are arranged in one row and more densely in the C. kegenicus males, whereas the pegs are arranged in two or even three rows, and the pegs are organized relatively widely in the C. karelini stridulatory file ( Fig. 4 ). In another species relative to C. karelini , C. albomarginatus , the male pegs also form one straight row. However, C. albomarginatus does not occur in Kazakhstan, inhabiting more northern territories. Thus, distinguishing C. kegenicus from C. albomarginatus is not so relevant. The females of C. kegenicus differ from the females of both C. albomarginatus and C. karelini by the well-developed stridulatory pegs. This feature, however, does not allow distinguishing the females between C. kegenicus and C. angulatus . On the proximal third of stridulatory file, the pegs are arranged in a sinuous row in the C. kegenicus males but in a straight row in the C. angulatus males ( Fig. 4 E, G ). The R vein of tegmen is clearly sinuate in the C. kegenicus males but straight in the C. angulatus males, and stigma is well developed in both sexes of C. kegenicus but is often absent in both sexes of C. angulatus ( Fig. 7 C–F ).

Calling song. As a rule, a male of C. kegenicus produces from 6 to 11 echemes separated by intervals of 0.7–1 s ( Fig. 9 ). Each echeme lasts for 0.7–1 s and consists of 5–6 syllables repeated at the rate of about 7.5 /s. The syllable duration varies in the range of about 130–190 ms. Each syllable starts with a short and loud pulse, followed by a very soft buzzing sound. Oscillographic analysis shows that the loud pulse is produced by the strong downstroke of usually one leg and the soft sound is produced by the low-amplitude vibrations of both legs ( Fig. 9 C ). The two legs are often moved asynchronously and change their roles in producing the loud pulse from syllable to syllable.

The calling song of C. kegenicus greatly differs from those of C. angulatus and of the species of the C. albomarginatus group, which was written above.

Courtship song. The courtship song of C. kegenicus starts with the synchronous, small-amplitude movements of the hind legs, which generate quiet syllables repeated at the rate of 3.5–6 /s (element 1; Fig. 10 A ). The loudest component of the syllables is generated by the down leg movements. In about 0.2–1 min, there comes an element 2: each second syllable starts to be produced by synchronous high-amplitude stroke of the legs ( Fig. 10 A, C ). As a result, a short loud pulse is produced at the rate of 3–3.5 /s. The element 2 lasting from 5 to 30 s is followed by an element 3, which is generated by rather complex leg movements ( Fig. 10 D, E ). Each leg alternates 3–4 low-amplitude and one high-amplitude movements, and superimposed on high-amplitude movements are small-amplitude vibrations. Notably, a louder sound is produced during the low-amplitude leg movements and at the beginning of each high-amplitude stroke. The loud pulse at the beginning of each high-amplitude stroke is produced by only one leg, and the two legs alternate their roles ( Fig. 10 E ). In the developed courtship, the element 2 (lasting about 5–10 s) and the element 3 (lasting about 3–4 s) may alternate for more than 1 min. Sometimes, the element 2 is preceded by the short element 1, so the complex of elements 1-2-3 may be repeated many times for two minutes or more.

It is remarkable that not a single element of the courtship song resembles the calling song in C. kegenicus , which differs this species from both C. angulatus and C. karelini . The courtship songs between C. kegenicus and C. karelini differ greatly, which was mentioned above. The difference in the courtship songs between C. kegenicus and C. angulatus is less striking, although the syllable periods and the temporal structure of syllables in the elements 2 and 3 are quite different.

Figures

FIGURE 4. Proximal part of the stridulatory file on inner side of hind femur: Chorthippus karelini male (A), female (B); C. albomarginatus male (C), female (D); C. angulatus male (E), female (F); C. kegenicus sp. nov. male (G), female (H). Scale 200 mkm.

FIGURE 7. Tegmina of Chorthippus karelini male (A), female (B); C. angulatus male (C), female (D); C. kegenicus sp. nov., paratypes, male (E), female (F) and C. kegenicus sp. nov., paratypes, head and pronotum, dorsal view in male (G) and in female (H). Scale 2 mm.

FIGURE 9. Oscillograms of the calling songs in Chorthippus kegenicus sp. nov. from Kazakhstan (locality 11) and Kyrgyzstan (locality 12). Song recordings are presented at three different speeds (faster oscillograms of the indicated parts of the songs shown in B–C and E–F). In all oscillograms the two upper lines are recordings of hind leg movements and the lower line is the sound recording.

FIGURE 10. Oscillograms of the courtship songs in Chorthippus kegenicus sp. nov. from Kazakhstan, locality 9 (A) and locality 10 (B). Song recordings are presented at two different speeds (faster oscillograms of the indicated parts of the songs shown in C–E). In all oscillograms the two upper lines are recordings of hind leg movements and the lower line is the sound recording. Different elements of the courtship song are indicated.