Bioacoustics of Ducetia laniae

Description. Habitus typical of Ducetia japonica species group; generally pale green with head and pronotum on dorsum yellow green, tegmina with stridulatory area and anal margins and legs (sometimes) brown when alive ( Figs 1–3 ). Frontal rostrum conical, stout, with subacute apex; upper tubercle having median sulcus distinct ( Fig. 4A ). Eyes oval and globular; in anterior view taller than wide ( Fig. 4B ); in dorsal view faintly protruding anteriorly ( Fig. 4A ); in lateral view obliquely elongated ( Fig. 4C ). Mouthparts generally light colored ( Fig. 4B ). Apical segment of maxillary palpi longest, slender, slightly curved, apex obtuse; fourth distinctly shorter than third segment in length ( Fig. 4C ). Pronotal disc not covering stridulatory area; 1.3–1.8 times as long as wide; anterior margin straight; slightly widening apically; median sulcus not distinct; lateral keel distinct near anterior and posterior margins; posterior margin broadly rounded 1.4–1.8 times as long as anterior margin ( Fig. 4A ). Pronotal lateral lobe rectangular, 1.3–1.5 times as long as tall; with ventral margin fairly elongated and straight; anterior margin slightly concave; posterior margin broadly rounded ( Fig. 4C ). Thoracic auditory spiracle (= thoracic foramen) large and bean-shaped; partly or fully covered by pronotal lateral lobe ( Fig. 4C ). Tegmen fully developed, well surpassing hind knees; infumated; rather narrow, with oblique apex; venation typical of Ducetia japonica species group: with 4–6 closely parallel posterior branches ( Fig. 3A ). Hind wing surpassing tegminal apices, reaching or surpassing middle of hind tibia; exposed part infumated ( Fig. 3 ). Legs generally long and slender ( Fig. 3 ). Fore and middle legs and hind tibia sometimes brown ( Fig. 1–3 ). Fore femur with both internal and external ventral margins having two to three very small spines, usually at apical half; middle femur with ventral margin having seven or eight small spines; hind femur with ventral margin having circa four spines widely spaced apart. Inner and outer knees of hind femora with rounded lobes each having a small apical spine. Fore tibia with both tympanum oval and open ( Fig. 3A ). Tibia ventrally and dorsally typically with numerous outer and inner dark-colored spines. Male. 1A vein on left tegmen straight and swollen ( Fig. 4A ). Stridulatory file on 1A vein of left tegmen, in ventral view, about 1.7 mm long, mostly straight but slightly curved at basal end, with 97 stridulatory teeth; at anal end having teeth particularly densely packed, at basal end having teeth more widely spaced apart; tooth length generally increases from anal end to maximum of 0.12 mm before decreasing drastically at basal end ( Fig. 4D ). Average tooth length at anal third 0.07 mm , at middle 0.08 mm , at basal third 0.10 mm ( Fig. 5A ). Average inter-tooth distance at anal end and middle region 0.014 mm , indistinctly smaller than at basal end of 0.030 mm ( Fig. 5B ). Mirror area of left tegmen rectangular with anterior and posterior margins parallel, anal and basal margins slightly converging posteriorly; anterior margin 1.2–1.3 times as long as posterior margin, 1.8–1.9 times as long as the length of mirror ( Fig. 4A ). Abdominal apex typical of Ducetia japonica species group. Cercus in lateral view with basal half cylindrical and straight; with apical half curved dorsad; with apical third having characteristic interno-ventral ridge ( Fig. 4E ). Subgenital plate elongated; apical half deeply and narrowly emarginated at middle; with inner margins of emargination nearly touching each other except at basal end ( Fig. 4F ). Female ( Fig. 6 ). Habitus similar to male ( Figs 6A–C ). Ovipositor falcate with dorsal valve having dorsal margin from basal third dentated; with ventral valve having ventral margin dentated only at the apex ( Fig. 6D ). Subgenital plate small; in lateral and ventral view, triangular; apex subacute ( Fig. 6E ). Measurements ( 2♂ , 1♀ in mm). See Table 1 .

Diagnosis. This new species is typical of the Ducetia japonica species group by the male cerci having long interno-ventral ridge and the tegmen having 4–6 closely parallel posterior branches that do not bifurcate. Ducetia laniae sp. nov. differs from other species by the absence of distinctly larger teeth in the anal part (similar to D. adspersa and Ducetia javanica (Brunner von Wattenwyl, 1891)) , and having distinctly more teeth, with a row of closely packed 97 teeth (see Heller et al. [2017 , Table 4]). Likewise in D. adspersa from Luzon ( Philippines ), the number of teeth on the stridulatory file is notably lower, with fewer than 30 teeth, than D. laniae sp. nov. Ducetia laniae sp. nov. also differs by the calling song, which is relatively simple, consisting of an echeme-sequence made up of a closely-spaced repetition of echemes (see below).

Calling song ( 1♂ , 28.6°C) ( Fig. 7 ). The calling song is an echeme-sequence composed of complex echemes (n = 2), and has a duration of 8.28– 10.67 s . Each echeme-sequence is made up of 46–56 echemes. The average echeme duration is 0.18± 0.02 s (0.15– 0.23 s ), and the average interval between consecutive echemes is 20.8±2.4 ms (16.0–23.7 ms). At the start of each echeme, the first syllable is particularly long, having a duration of 12.8±2.5 ms (8.4–18.3 ms), and has the highest amplitude. The average interval between the first and second syllables is 9.0±3.8 ms (4.9–16.5 ms). The remaining part of the echeme consists of 16±3 (13–21) syllables and has an average duration of 0.16± 0.02 s (0.14– 0.20 s ). These syllables show up as possibly rapid-decay pulses. The average syllable duration is distinctly shorter than the first syllable, i.e., 5.5±1.0 ms (3.4–7.1 ms), and the average interval between these consecutive syllables is 5.4±1.5 ms (2.3–7.5 ms). The call spectrum is broad-band, and has a peak frequency of 17.2±1.1 kHz (15.8–20.8 kHz).