Bioacoustics of Plangia variacantans

Description. Male. General habitus and colour pattern . Medium-sized Plangia with elongate tegmina and pointed alae giving especially the male an acute appearance. Colour light green to yellowish-green with faint dark spots and patches on tegmina ( Fig. 8 A ). Stridulatory area dark. Area of tympana on fore legs violet. Laterally on abdomen reddish patches on each segment, a reddish patch also on pleura of pronotum. Eyes striped. Head and antennae . Antennae filiform, of whitish to tawny colour, shorter than flexed tegmina (about 33 mm long; N=1). Face predominantly white with few green patches, eyes oval. Fastigium verticis deeply sulcate, reddish with blunt anterior apex, laterally slightly compressed, broader than width of scapus. Fastigium of vertex and fastigium of face meeting in deep sulcus. Thorax. Pronotal disc flat ( Fig. 8 A ). Lateral pronotal lobes deeper than wide, ventral margin evenly rounded, anterior margin almost straight. Fore coxa with spine. All femora laterally compressed; dorsally unarmed. Fore femora with laminate outer expansion ventrally and 2–4 black-tipped spines distally. Mid femora distally with 2–3 black-tipped spines on outer ventral margin. Hind femora with 4 black-tipped outer spines. Fore tibiae inflated in area of oval and open tympanum; ventrally with 2–3 outer and 1–2 inner spines. At apex pair of inner spurs, on outer side only 1 spur, thus apex with three spurs and one rounded unarmed lobe. Mid tibiae ventrally with 5–6 outer spines and 1 inner spine. All spines black-tipped. Spurs as in fore tibiae. Hind tibiae with four rows of slender black-tipped spines getting denser distally. Dorsal one pair of spurs, ventrally 2 double pairs of spurs. Wings. Sc and R contiguous, except near base and at the very end of the tegmen where both veins run apart. Tegmina elongate with oval tip. Hind wings hyaline, longer than tegmina, visible part when folded of same colour as tegmina. Stridulatory file thick. Continuously, at both sides teeth decreasing in size ( Fig. 9 D ), approximately 65 teeth (N=1). Abdomen. Plump, laterally green with reddish patch on each segment and white venter. Dorsal with red broad fascia. Tenth tergite unmodified, posterior margin with two broadly rounded lateral edges and depressed central part ( Fig. 9 A, B ). Cerci stout, hairy, inwardly curved with sclerotized tips ( Fig. 9 B ). Subgenital plate deeply v-shaped incised and with very long, round styli ( Fig. 9 C ). Female. General habitus, colour pattern and spination as male but without dark patch on left tegmen ( Fig. 8 B ). Ovipositor strongly up-curved with serration on both valves ( Fig. 10 A ). Subgenital plate elongated triangular ( Fig. 10 B ). Measurements. males (N = 3) Total length of body 18.5–23 mm Median length of pronotum 5.3–5.4 mm Length of hind femur 15.1–16.5 mm Length of tegmina 33.5–35 mm females (N = 4) Total length of body 22.0– 25 mm Median length of pronotum 5.2–5.6 mm Length of hind femur 14.5–16.2 mm Length of tegmina 33–37 mm Lateral length of ovipositor 6.2–6.5 mm Diagnosis. Five Plangia species are described on the female sex only, three of them occur on Madagascar . Plangia guttatipennis Karsch, 1889 described from Madagascar is similar to P. variacantans n. sp. in habitus and colour pattern. In difference to P. variacantans n. sp. the subgenital plate of P. guttatipennis is smaller and less elongate and the ovipositor is smaller and differently shaped. Distinguished from female P. nebulosa Karsch, 1890 described from Cameroon who is also similar in habitus and colour pattern by a much smaller subgenital plate in P. nebulosa and a differently shaped ovipositor. For P. albolineata (Brunner von Wattenwyl, 1878) Brunner von Wattenwyl states that it is distinguished from all other Plangia species by a blunt fastigium verticis and its large body size of 30 mm (B. v. Wattenwyl 1878, p. 328). Plangia karschi Chopard, 1954 from Guinea in West Africa has a broader and not as elongate subgenital plate. Plangia villiersi Chopard, 1954 from Madagascar has a similar subgenital plate but its habitus is completely different from P. variacantans n. sp. being larger and stouter and with much broader tegmina. Males of P. variacantans n. sp. are distinguished from all other Plangia species by their elongate and deeply divided subgenital plate with long and slender styli.