Bioacoustics of Rhacocleis parnassica

Description Male (figs 1, 3, 5). Medium size. Integument silky glossy, smooth. Head. Fastigium of vertex parallel sided, convex, slightly wider than scapus. Pronotum (figs 8–9). Pronotum subcylindrical, edges rimmed, in profile straight lightly undulating, metazona relatively short, dorsum very slightly convex without median keel, roundly merging with lateral lobe, hind margin weakly convexly rounded, humeral excision weak, impressed; lateral lobes slightly laterally spread, along fore and lower edges impressed. Prosternum on either side with a tiny spine, mesosternum with low triangular projections, similar projections of metasternum wider but less extending. Thoracic tympanum widely open, strongly elongate. Fore wing. Tegmina reaching hind margin of 1 st tergite; left forewing (fig. 10) about as wide as long; for edge weakly convex, apex broadly obtuse; hind edge with distinct cubital sinus; Sc, R and M veins well raised; SC and R reaching edge, subparallel, proximally slightly diverging, apically slightly converging; M almost reaching the edge. Stridulatory file (fig. 11) as seen from below short, shortest distance between proximal and distal end, ca. 3 mm , at the proximal and distal end curved, remainder straight, apical half slightly more raised; total number of teeth about 60, of which ca. 35 are strongly sclerotized; widest spacing between teeth about halfway 8 teeth per 0.5 mm , distance between middle of two successive teeth is 0.06 mm ; greatest width of middle teeth 0.13 mm . Legs. Hind femur not very slender, 4.9 times longer than wide about three times as long as pronotum, fore femur shorter than pronotum. Tibial tympanum slit-like. Plantulae of hind tarsus three quarters as long as first tarsal segment. Fore femur with 2–3 tiny spines in apical half of inner margin, mid femur unarmed or with a single tiny spine along outer margin, hind femur with 3–4 and 5–6 tiny spines along the mid part of the lower outer and inner margin respectively; inner and outer genicular lobes of fore and mid femora with 2 in hind femora with 1 tiny spines; upper inner (=anterior) margin of fore and mid tibia (fig. 7) with 1–2 spurs (in the fore tibia, a proximal one at the distal end of the tympanal opening, that may be absent, and one in the mid third of the tibia); upper outer (=posterior) margin of fore and mid tibia with 3 spurs (in the fore tibia, a proximal one at the distal end of the tympanal opening, one halfway the tibia and an apical one); both lower margins of fore and mid tibia with 6 spurs; tip of hind tibia with a pair of ventral outer apical spurs without a pair of pits in between them. Abdomen (figs 12–17). Abdominal tergites scarcely folded along midline, no true median keel. Last tergite (fig. 12) slightly hairy along the middle as distal tergites; hind margin rimmed, forming two small triangular acute lobes pointing distally with wide V-shaped median excision. Cercus (figs 14–15) hairy, robust, conical, gradually, and weakly inward bent terminating in an acute tip, pointing downward and inward; inner side at a quarter of the length with a strong compact side tooth with inner margin concave and tip pointing forward. Paraprocts small, knoblike structures not elongated. Subgenital plate (fig. 13) rather compact, as long as basal width, tapering with an indistinct median keel, hind margin wide U-shaped emarginated; styli slender, cylindrical, pointing distad. Titillator (figs 16–17) slender, thin, well sclerotised, basal fusion of right and left titillator membranous, basal part ca. twice as long as apical part, pointing in same vertical direction, widened, slightly twisted; apical part towards the tip flattened and slightly curved, tip hook-shaped, surface smooth. Colouration (figs 1,3,5). Predominantly unicolorous, in live specimen pearl grey to pale buff, some parts with a greenish haze, distinctly mottled with dark brown. Antennae with flagellum unicolorous brown, scape and pedicel sometimes with darker markings. Head of general colour, commonly marbled with brown, labrum and lower half clypeus and genae pale, not mottled. Pronotum of general colour, marbled with brown, the center of the pronotal dorsum with a symmetrical black W-shaped blackish patch, lateral lobe uniformly coloured, with a unmottled stroke along hind margin below humeral excision. Fore wing black, small apical part between R and M and some veinlets yellowish, fore margin transparent with greenish haze. Legs of general colour, variegated with dark brown, insertion of spurs commonly black, spurs brown.All femora of general colour mottled with dark brown, except for black pre-genicular incomplete ring, in mid and fore femora apically bordered by white dorsal ring, lacking any other black markings, or hind femur near the base with small black dorsal patch. Tibiae predominantly pale, except for the insertion of the spurs, tympanal area of the fore tibia, apical part of the hind tibia with a greenish haze. Plantulae dark, tarsi pale cream or greenish with dark patches. Abdominal tergites of general colour, hind margins tergites with a tiny median black dot. Pro-, meso-, metanotum, sternites and subgenital plate all unicolorous pale grey white. Male cercus pale, the apical half with a greenish hue. Female (figs 2,4,6). Head, thorax and legs as in male. Micropterous, tegmina lateral, almost completely covered by pronotum, oval, not reaching front margin of first tergite. Fore femur only slightly shorter than pronotum. Abdominal sternites, including the seventh not modified. Cerci conical, hairy, evenly narrowing to a pointed apex. Ovipositor (fig. 19) ensiform, relatively long and slender, 0.9 as long as the hind femur, in the apical third weakly curved upward, margins smooth. Subgenital plate (fig 18) along entire length with strongly developed median keel, with bristle like hairs, widening from the base, widest in the middle; the basal half on each side of the keel with a wide rounded ridge which runs from the proximal margin parallel and close to the keel, at one third of the length deflecting to the side, forming a deep, large laterally opening pit; apical half narrowing, trapezoid, depressed besides the keel, sides with bristle like hairs, lateral margins near the apex bend inward forming inward pointed, rectangular lobes separated by wide V-shaped excision. Gonangulum elongate, simple. Colouration (fig. 2, 4, 6) as male but paler. Tegmina unicolorous pale. Head, thorax and legs unicolorous. Abdomen unicolorous except for hind margins of the tergites with a tiny median black dot. Bioacoustics The calling song consists of echemes repeated at relatively slow tempo, about every 10s. Echemes last about 500ms (460–560ms) and consist of nine syllables (8–10), the first one (or sometimes two) last somewhat longer than the following ones. Both opening and closing hemisyllables are visible. The interval between the first and second hemisyllable is substantially longer than those of the following syllables. Syllables (except first one) last 50ms (46–54ms) being repeated at the rate of 18–19/s. The frequency spectrum of the song is between about 18–80kHz, with a maximum around 30kHz. Measurements (length in mm) and ratios Body ♂ 20.0–21.2, ♀ 21.7; pronotum ♂ 4.8–5.4, ♀ 5.6; elytron ♂ 1.1–1.7, ♀ 0.0; hind femur ♂ 15.2–16.0, ♀ 17.6; ovipositor 15.0. Ratio hind femur/pronotum ♂ 3.0–3.2, ♀ 3.1; ovipositor/pronotum 2.7; hind femur/ovipositor 1.2.

Differential diagnosis R. parnassica sp.nov. is well defined and clearly differs from most other Greek species of Rhacocleis by the relatively compact cercus in the male with a strong inner side tooth at one quarter of the length. The male cercus resembles those found in R. anatolica , R. Sylvestri and R. werneri but in these three species the cercus is slimmer, and the side tooth placed closer to the base. Differences with R. distinguenda are more subtle, the cercus in R. distinguenda being more robust and the side tooth being less well defined. Besides, the two species differ in the acute lobes along the hind margin of the last tergite which are more pronounced in R. parnassica sp.nov. and the titillator in ventral view is gradually narrowing along most of its length in R. distinguenda instead of suddenly narrowing in the apical third in R. parnassica sp.nov .. Female R. parnassica sp.nov. can be easily distinguished from congenerics by the shape of the female 7 th sternite and subgenital plate. With the 7 th sternite being flattened, unmodified and not raised, R. parnassica sp.nov. clearly differs from species in which this sternite is modified e.g. R. werneri , R. silvestrii , R. distinguenda , R. anatolica and R. turcica . The overall shape, especially the presence of a central keel and short outward bend ridges in the proximal half forming deep pits in female R. parnassica sp.nov. resembles those found in R. werneri , R. turcica and R. anatolica but differs in the overall shape and the rather deeply excised apical part. Bioacoustics. In many species of Rhacocleis , the main structure of the song is very much like R. parnassica sp.nov. Differences between species especially reside in the number of syllables per echeme, although several species show overlap in this respect. The song of R. parnassica sp.nov. in the number of syllables resembles the songs of several species, including R. germanica , R. annulata , R. buchichii , R. insularis and R. distinguenda . As far as we know only R. germanica occurs in the same area as R. parnassica sp.nov. As both species seem to produce identical songs, this suggests there are other barriers to keep the species separate. The phenomenon of similar songs but differences in the morphology, particularly the male genitalia, has also been reported for Eupholidoptera ( Çiplak et al. 2009 ) .