Bioacoustics of Horatosphaga scalata

Diagnosis. Horatosphaga scalata n. sp. belongs to a group of species with an unmodified tenth abdominal tergite and is thus distinguished from species with an enlarged or otherwise modified 10 th abdominal tergite such as H. parensis Hemp, 2002 , H. elgonensis (Chopard, 1838) , H. ruspolii (Schulthess, 1898) , H. diminuta (Chopard, 1954) , H. vicina (Chopard, 1954) , H. inclusa (Karsch, 1893) , H. crosskeyi Ragge, 1960 and H. laticerca n. sp. In habitus and venation similar species are H. leggei (Kirby, 1909) , H. serrifera Schaum, 1853 and H. magna Ragge, 1960 . These species also have an enlarged medial area with crossveins symmetrical arranged and arched towards the tegminas’ tips, especially in H. leggei while in H. magna and H. serrifera these crossveins are only slightly or not arched. H. leggei and H. magna , however, have differently shaped posterior margins of the subgenital plates. In H. leggei the posterior margin of the subgenital plate is deeply u-shaped incised, while in H. magna lateral processes are developed (similar to H. scalata n. sp. ) but the area between these processes is wavy with a shallow median incision, while in H. scalata n. sp. the margin is straight. H. magna is also much larger in body size and length and broadness of the tegmina than H. scalata n. sp. and is only known from northern Kenya and Ethiopia at present. Also H. serrifera is a species with broad tegmina and a medial area expanded with regularly set crossveins. But as in H. magna these veins are not strongly arched towards the tegmens tip but almost straight. The subgenital plate of H. serrifera is slightly incurved and does not form processes at its edges. Song. Only few series of echemes were heard from H. scalata n. sp. in the afternoon and evening. Within one series, the echemes (inter-echeme-intervals around 10 s) increased in duration and amplitude (last echeme of a series shown in Fig. 18 ). In the crescending first third of the echeme, the short syllables were produced at a rate of about 12 Hz. During the second and the final third the syllable rate was much lower (ca. 5–6 Hz at 21ºC) and the amplitude remained constant ( Fig. 19 ). The echemes are thus much shorter und simpler than they are typically in the song of H. leggei (compare both species in Fig. 19 ; see also Heller et al . 2014 ). The peak of the carrier frequency was between 15 und 20 kHz ( Fig. 20 ). Habitat. Grasslands and clearings in Miombo woodlands.

Description. Male. Color green, with legs dark and creamy striped. On head and pronotum dark median fascia ( Fig. 8 , 9 A–C). Head and antennae : Antennae long and thick, of reddish colour. Fastigium verticis consisting of two bulges, a deep gap between the bulges and another large gap to the conical fastigium of the face. Tegmina and wings. Tegmina longer than twice the body length; tips of alae green, surpassing tegmina; around stridulatory area of left tegmen light brown marking ( Fig. 8 ; Fig. 11 C ). Anterior medial area of the tegmina broadened in the middle, its crossveins strongly arched towards the wing tip. Also costal area broad with regularly arranged crossveins arching towards the tip. Stridulatory file as in Fig. 10 , consisting of two parts, parted by gap. Inner part with large, densely set teeth, outer part with smaller, more widely set teeth. With small mirror on right wing ( Fig. 11 C ). Legs. Tympanic auricles conchate, strongly inflated ( Fig. 8 , Fig. 9 C , Fig. 11 D ). Fore and mid femora with ventral double row of irregular set spines, hind femora unarmed or almost so; tibiae quadratic in diameter, fore and hind tibiae with four rows of densely set spines, mid tibiae only with double row of ventral spines, dorsally unarmed. Abdomen . 10 th abdominal tergite unmodified with almost straight posterior margin. Cerci thick and round, tips sclerotized and inwardly curved ( Fig. 11 A ). Subgenital plate elongated, with two short lateral processes ( Fig. 11 B ). Female. Unknown. Measurements, males (mm) (N=6). Total length of body 18.2–21.1; Median length of pronotum 5.4–6.7; Length of hind femur 33.4–34.1; Length of elytra 35.8–39.7.