Bioacoustics of Sichuana taiji

Diagnosis. The new species superficially resembles Sichuana planicercata Gu, Zheng & Yue, 2023 , but can be differentiated from the latter by the following characters: 1) male left tegmina with more numerous distinct stridulatory teeth, and 2) male cercus inner basal part robust and expand inward. In addition, Sichuana taiji sp. nov. can be differentiated from S. curvicercata Gu, Zheng & Yue, 2023 by the following characters: 1) male left tegmina with more numerous distinct stridulatory teeth, 2) posterior margin of male 10th abdominal tergite medially with a shallow concave, form a pair of lobate projections, and 3) male cercus slightly bent toward ventral side, but apex not pointing dorsally, inner tooth not straight which apex not suddenly sharp and incurved. Sichuana taiji sp. nov. can be differentiated from S. longilamina Gu, Zheng & Yue, 2023 by the following characters: 1) prosternum with a pair of distinctly smaller processes, 2) lateral field of male tegmen relatively narrower, 3) posterior margin of male 10th abdominal tergite with a depressed wide rounded area, 4) male cercus not pointing dorsally and basal part of inner tooth more robust, and 5) male subgenital plate not elongate, with a relatively shorter styli. Sichuana taiji sp. nov. can be differentiated from S. cryptospina Shen & Yin, 2020 by the following characters: 1) prosternum with a pair of distinctly smaller processes, 2) lateral field of male tegmen relatively narrower, and left tegmina with more numerous distinct stridulatory teeth, 3) basal part of inner tooth on male cercus robust and expand inward. Sichuana taiji sp. nov. can be differentiated from S. feicui He, 2020 by the following characters: 1) prosternum with a pair of distinctly smaller processes, 2) lateral field of male tegmen relatively narrower, 3) male cercus strongly incurved at the middle which apex acute, basal part of inner tooth robust and expand inward. Sichuana taiji sp. nov. can be differentiated from S. magnicerca Gu, Zheng & Yue, 2023 by the following characters: 1) prosternum with a pair of distinctly smaller processes, 2) lateral field of male tegmen relatively narrower, 3) male cercus relatively smaller and shorter, not extending beyond subgenital plate, with inner tooth distinctly larger, basal part robust and expanded inward.

Description. Male. Body relatively large in Drymadusini . Head . Frons slightly oblique backward. Fastigium of vertex slightly wider than the scape of antenna ( Figs. 2 AB). Median ocellus visible, oval ( Fig. 2A ). Compound eyes broadly round and projecting outward ( Figs. 2 ABC). Thorax . Disc of prozona with a broadly obtuse concavity in the middle of each side, anterior margin of pronotum slightly concave and posterior margin blunt, lateral carina faintly indicated in prozona and distinct in metazona, first transverse sulcus slightly concave backward, central transverse sulcus “V” shaped, posterior transverse sulcus absent, median carina distinct in prozona and slightly obscure in metazoan, lateral lobes longer than deep, with weakly humeral sinus ( Figs. 2 ABC). Prosternum with a pair of small conical processes ( Fig. 2D ). Mesosternum with a pair of acute triangular lobe-shaped processes, nearly equal in width to height; metasternum with a pair of obtuse triangular lobe-shaped processes, width distinctly broader than height ( Fig. 2D ). Wings . Mesopterous, about 1.3 as long as pronotum, with clear longitudinal and cross veins; lateral field gradually and slightly widens from base, apical half not distinguish expend ( Figs. 2 EFHI, 3AB). C weak, reach about 3/5 of the wings ( Fig. 3A ). Sc strong, with 3–4 branches, first branches sometimes fused with C which reach about 4/5 of the wings ( Fig. 3A ). Rs branching about in basal 2/3 part of tegmina, with 2 branches ( Fig. 3A ). Stridulatory file on Cu2 of left tegmina with 3/5 basal part bearing 27–31 distinct stridulatory teeth, and 2/5 apical part with about 50 indistinct small teeth ( Figs. 2G , 6A ). Stridulatory file on Cu2 of right tegmina with 2/5 basal part with about 30 indistinct small teeth, and 3/5 apical part bearing 29–35 distinct stridulatory teeth ( Fig. 2J ). Mirror on right tegmina ovoid, around 1.3 times longer than wide ( Fig. 2J ). Hind wings rudimentary, longer than half of the pronotum, 3 primary veins with relatively high numbers of spinules, and 1 primary vein with a few spinules sparsely arranged ( Figs. 2K , 6C ). Leg. Fore coxae with 1 long spine; fore femora shorter than pronotum, dorsally unarmed, ventrally with 1–4 internal spinules and externally unarmed, genicular lobes with 0–2 internal spinules and externally unarmed; fore tibiae both sides with crack-shape tympana, dorsally with 3 externally spines and internally unarmed, ventrally with 6 pair of spines, a pair at the apical. Middle femora dorsally unarmed, ventrally with 0–2 internal spinules and 0–4 external spines, genicular lobes with 1 internal spinule and 1–2 external spinules; middle tibiae dorsally with 4 internal spines and 2 external spines, ventrally with 6 pair of spines, a pair at the apical. Hind femora dorsally unarmed, ventrally with 4–10 internal spinules and 6–10 external spinules, genicular lobes unarmed; hind tibiae dorsally with 20–27 spines on both sides and 1 pair of apical spurs, ventrally with 5–8 spines on both sides, 1 pair of subapical spines, and 2 pair of apical spurs. Abdomen . Posterior margin of 10 th abdominal tergite with a wide rounded area, which pileous, slightly depressed, and posterior margin medially with a shallow notch, its sides forming a pair of round, blunt lobes, which lack strongly sclerotized margins ( Figs. 4 ACD, 7AD). Epiproct triangular, visible from dorsal view. Cercus stout, pileous and conical, incurved at obtuse angle from midlength, slightly bent ventrally, apex acute; with inner tooth near base, basal part robust and expanded inward, apical part gradually thined and incurved, apex acute. Subgenital plate length greater than width, with 2 lateral carinae, posterior margin medially with a deep sharped notch; width of notch varies; stylus slender and obviously longer than notch ( Figs. 4B , 7C ). Genitalia. Titillators “L” shaped, with long apical portions basal bear 3 row of denticles, and some scattered denticles in addition ( Figs. 4E , 7B ). Female. Generally similar to male. Tegmina brachypterous, slightly shorter than pronotum ( Figs. 5 CF). Hind wings rudimentary, brachypterous, longer than half of the pronotum ( Figs. 5I , 8 EH). Cercus conical and pileous ( Figs. 5G , 8F ). Posterior margin of 10 th abdominal tergite with a wide rounded area, which pileous, slightly depressed ( Fig. 8G ). Subgenital plate nearly trapezoid, width greater than length, with 2 lateral carinae, middle of posterior margin with a wide triangular shallow notch ( Figs. 5H , 8G ). Ovipositor shorter than hind femora, obviously beyond apex of hing femora, apical part slightly decurved ( Fig. 5D ). Coloration. Body dorsally generally brown, dark brown, yellowish brown, or reddish brown, with much irregular light patches; ventrally light yellowish brown or rosybrown. Median ocellus light yellowish brown. Compound eyes black, upper part light while alive. Tegmina generally yellowish brown or dark brown, male stridulatory apparatus area on dorsal field black, lateral field with numbers of black irregular patches. Spinules on hind femora black. Ovipositor dark brown, apical part black. Measurements (mm). Body (from head to tip of abdomen): ♂ 21.07–34.06, ♀ 23.24–33.46; pronotum: ♂ 7.05– 8.46, ♀ 7.53–8.50; tegmina: ♂ 8.58–14.29, ♀ 6.24–7.93; fore femora: ♂ 5.74–7.26, ♀ 7.16–7.70; middle femora: ♂ 6.57–8.17, ♀ 7.42–8.65; hind femora: ♂ 17.34–22.02, ♀ 22.48–24.77; fore tibiae: ♂ 6.76–7.96, ♀ 7.42–8.65; middle tibiae: ♂ 7.30–9.02, ♀ 9.28–9.65; hind tibiae: ♂ 16.24–21.28, ♀ 21.15–24.47; ovipositor: 17.31–20.63.