Hexacentrus ashoka Ghosh, Jaiswara & Rajaraman, 2023

Ghosh, Aarini, Jaiswara, Ranjana, Sabharwal, Shagun, Dasoju, Vivek, Bhattacharjee, Anubhab & Rajaraman, Bittu Kaveri, 2023, Description of three new species of predatory Genus Hexacentrus (Orthoptera Tettigoniidae) from India, with bioacoustic and morphological characterizations, Zootaxa 5249 (3), pp. 335-356 : 345-350

Hexacentrus ashoka Ghosh, Jaiswara & Rajaraman sp. nov.

Type material. Holotype, ♂, INDIA: Haryana, Sonipat, Rai, Rasoi ~ 315 m a.s.l., VIII.2021, 28°56′48.78″ N; 776′5.19″ E, AG_SO1_M3 ( ZSI) . Allotype _ ♀,AG_SO1_F5, same locality as holotype ( ZSI) . Paratypes (2 ♂, 3♀), same information as holotype, VII–IX.2020 –2021: 1 ♂ (AG_ SO1 _M1), 1 ♂ ex-AG_SO1_M2 ( BNHS) ; 2♀ (AG_ SO1 _F1, AG_SO1_F2), 1♀ ex-AG_SO1_F4 ( BNHS) .

Type locality. Ashoka University , Rai, Sonipat, Haryana, India .

Distribution. The species is currently known only from its type locality.

Etymology. The species is named after the Ashoka University located in Sonipat, Haryana. The project was carried out with the support and research grant funding provided by Ashoka University. The University is in turn named after the pluralistic and peace-loving Ashoka, after whom this species has been named.

Diagnosis. The species can be differentiated from H. khaisiensis sp. nov. by the pronotum having anterior margin slightly concave, pronotal disc flat, posteriorly expanded, broadly rounded, posterior margin concave with slight median excision. The M vein is much more curved, thick distally, CuP vein somewhat straight, space between CuP and CuA about same as between M and CuA, 1 st anal vein bearing the stridulatory file less inclined, ventral side with 40 teeth ( Fig.14B , 9 ). Cerci cylindrical at the base; it is broad with a tubercle on internal side then narrowing to small digitiform apical appendages with strongly incurved apex.

Description. Mostly similar to H. khaisiensis sp. nov. Except for the following characters.

Male. Body slender, medium-sized ( Fig. 7A–B ). Head. Fastigium verticis triangular, narrow, laterally compressed with a median longitudinal sulcus, and apex round in lateral view. At base of fastigium verticis is almost the same width as the scapus. Fastigium verticis is separated from fastigium frontis by a furrow. Eyes globular ( Fig. 7C–E ).

Pronotum. Saddle shaped, expanded in posterior region; with three transverse sulci, slightly depressed behind first transverse sulcus, third transverse sulcus is restricted to disc, “U” shaped sulcus presents between second and third transverse sulci, anterior margin slightly concave with no excision present. An hourglass-like brown band is present in the pronotum. Median carina is faintly visible ( Fig. 7C ). Pronotal disc is flat, posteriorly expanded, broadly rounded, posterior margin concave with slight median excision. Lateral margin of pronotum descending, longer than high, with the humeral sinus absent, anterior angle is round and anterior margin shorter than posterior margin from lateral view, posterior angle is obtuse. Thoracic auditory spiracle large, oval, slightly hidden under lateral lobe of pronotum ( Fig. 7D ).

Wings. Tegmina slightly shorter or the same as the length of hind wings. Tegmina long and crosses the mid tibiae of the hind leg. Male tegmina long, broad in middle, apex narrow round in lateral view ( Fig. 7B ). Stridulatory file broader at the tip and narrows towards the centre. Tooth length is different in different parts of the file, widest in the beginning. The stridulatory file has 40 teeth ( Fig. 9 ).

Legs. Fore coxae are provided with a forward outward projecting spine. FI with 4 subapical spurs and 1 apical spur, 16 spines in between sub-apical spurs on the inner margin, and approximately 27 spines with no subapical and apical spur on the outer margin.

TI dorsally unarmed and ventrally armed with 6 long subapical spurs inwardly bent, 1 st subapical spur slightly shorter than 2 nd subapical spur and then decreasing in length apically on both margins. TII is dorsally armed with two subapical spurs, sometimes absent, ventrally armed with 6 subapical spurs on inner and outer margins. TIII dorsally armed with 24–36 spines on the inner margin and 27–35 spines on the outer margin, TIII ventrally armed with 10–15 subapical spurs increasing in length and density each on the outer margin and 8–15 subapical spurs increasing in length and density towards tarsus.

Male Genitalia. Supra-anal plate triangular in shape with dorsal groove. Cerci are cylindrical in shape at the base; it is broad with a tubercle internal side then narrowing to small digitiform apical appendages with strongly incurved apex ( Fig.7F ). Subgenital plate is long with elongated, wide longitudinal median furrow, and lateral ridges are well developed, apical margin with wide V-shaped excision, styles curved, slightly thick at the base than apex, diverging basally and slightly converging apically ( Fig. 7G ).

Female. Pronotum. In dorsal view the posterior lobe of the female pronotum is less widened and rounded than in males ( Fig. 8C ). Wings. Hind wings and tegmina of same length and shape as in male ( Fig. 8B ).

Female Genitalia. Supra-anal plate triangular dorsal groove, short and broad at base and apex rounded. Subgenital plate triangular, small, with a dorsal groove, as long as wide, at end roundly excised ( Fig. 8I ). Cerci robust, upcurved, straight, thick at base narrow at apex, with smooth conical slightly inward appendages ( Fig. 8G ). Ovipositor dagger shaped, widest before mid-length, gradually narrowing towards end, apex pointed, serrated apically ( Fig. 8J )

Coloration. Overall green when alive ( Fig.2A ). Antennae with regularly spaced blackish brown annules. Occiput and vertex with a thick rusty brown stripe covering most of the head in dorsal view. Pronotum disc bearing rusty brown stripe less in width as of head up to half the length much widened posteriorly.

Acoustic measurements. The call of Hexacentrus ashoka call consists of two sections ( Fig. 10A ). The first part of the call consists of a group of low-amplitude chirps with variable chirp duration: the earlier chirps are longer (337 ± 1.7 ms for the first five chirps from this portion averaged across 3 individuals) and the later chirps are quicker (261 ± 18 ms for the last five chirps from this portion averaged across 3 individuals). There is also considerable variability in the inter-chirp interval, which also reduces over time (317 ± 10 ms for the first five chirps, 187.2 ± 13 ms for the last five chirps, n=3 individuals). The second part has a group of higher amplitude and well-defined sharp chirps that sound like short buzzing sounds ( Fig. 10B–D ). Each chirp ends with a quick single syllable tick of 2 ± 0 ms length. The high amplitude chirps have groups of 80.8 ± 2.13 syllables for a total duration of 194 ± 50 ms (n=7). Each syllable is 1.7 ± 1 ms in length with inter syllable duration of 1.2 ms. The SRR is 340 ± 18. The spectrogram is broadband with a bandwidth of 5 ± 0.8kHz and a peak frequency of 8.9 ± 0.13 kHz ( Fig. 10E–F ).

Figures

FIGURE 2. Picture of all 3 species in their natural habitat—H. khasiensis male (A) and female (B), H. ashoka male (C), H. tiddae male (D).

FIGURE 7. Hexacentrus ashoka male: (A–B) Dorsal and Lateral view of the specimen. Scale 5mm, (C–D) Dorsal and Lateral view of head and pronotum. Scale 5mm, (E) Face. Scale 5mm, (F) Supra-anal plate. Scale 1mm, (G) Subgenital plate dorsal view. Scale 1mm.

FIGURE 8. Hexacentrus ashoka female: (A–B) Dorsal and Lateral view of the specimen. Scale 5mm, (C) Dorsal view of head and pronotum. Scale 5mm, (D) Ventral view of Specimen, (E) Maxillary palpi. Scale 1mm, (F) Lateral view of head and pronotum. Scale 5mm, (G) Supra-anal plate. Scale 1mm, (H–I) Lateral and Dorsal view of the subgenital plate. Scale 1mm, (J) Ovipositor in lateral view.

FIGURE 9. SEM images of the file structure of Hexacentrus ashoka sp. nov in different magnifications.

FIGURE 10. Hexacentrus ashoka sp. nov. (A) Waveform of the whole calling song, (B–D) Oscillogram of the call at various time scales, (E) Spectrogram and (F) Power spectra of the calling song.

FIGURE 14. Stridulatory apparatus structure—ventral side of left wing with file and scraper on the dorsal side of right wing (A–B) of H. khasiensis; (C–D) of H. ashoka; (E–F) of H. tiddae.