Bioacoustics of Arantia (Euarantia) tanzanica

( Figs. 4 A–C, 30F–J, 31G–L, 55D–F) Diagnostic remarks. A large, green katydid, similar to A. fasciata ( Fig. 30J ) but lacking the white markings on the metazona of the pronotum but instead having two small dark patches on the opposite sides of the metazona ( Fig. 30H ). The front margin of the tegmen is bordered with a narrow yellow strip and the face is pale, almost white. The male cercus is more slender than in A. fasciata ( Fig. 31G ) and is distinctly bent downwards when seen from the side ( Fig. 31H ); styli of the subgenital plate are extremely reduced, almost invisible ( Fig. 31J ). Bioacoustics. The call of A. tanzanica is similar to that of A. fasciata and consists of short, 2–3 syllable echemes; each successive syllable in an echeme is successively louder than the previous one; mean syllable duration is 0.0723 s (SD=0.0137, n=11); the peak frequency of the call is 10.5–12.9 kHz ( Figs. 55 D–F). The call is loud and easily perceived by the human ear. In addition to the advertisement call, both males and females produce loud, broad frequency release calls if captured.

Diagnosis . A . tanzanica n. sp. is larger than A . rectifolia , has broader wings, and a different stridulatory area on the left tegmen (compare Figs 19 and 20 ). The stridulatory file is much longer in A . tanzanica n. sp. consisting of 90–110 teeth, being large in the middle and more widely spaced and smaller and more densely set at both sides while A . rectifolia has a comparatively short stridulatory file with more regular densely set 80 –85 small teeth (compare Figs 57 and 58 ). The fastigium verticis also differs between both species: A . rectifolia has a fastigium that is narrow triangular with a deep sulcus while in A . tanzanica n. sp. the fastigium verticis has posteriorly a broad base then narrowing suddenly midway and is more shallowly sulcate. Also the spination of the legs is different between both species. Otherwise both species are morphologically very similar.

Description . Male. General habitus and colour pattern. Large to medium sized species with broad wings, predominantly green with pair of dark patches lateral on posterior part of pronotum. Head and antennae. Eyes oval-roundish, dark. Antennae long and thin, tawny. Fastigium of vertex forming a ridge with a broad base suddenly narrowing anteriorly; sulcate; fastigium of frons conical; both fastigia separated by deep gap. Thorax and legs. Fore coxa without spine. Tympana of fore tibiae open on inner side, conchate on outer side, whole area slightly inflated. Fore femora on inner side with two ventral black spines, mid femora unarmed, hind femora with 4 inner and 8 outer black-tipped spines. Fore tibiae with 1 dorsal spine on apical part of inflated part anterior of tympana and 2 spinules more proximally. 2 pair of spurs; ventrally with double row of irregular set of 1–4 blacktipped spines. Mid tibiae with ventral row of 7–8 irregular set pairs of spines and 2 pairs of spurs. Hind tibiae tetragonal with 4 rows of numerous and irregularly set spines; dorsal 1 pair of spurs, ventral 2 pairs. Anterior margin of pronotum broadly rounded. Disc of pronotum slightly depressed on posterior part. Posterior margin of pronotum slightly incurved. Tegmina broad with evenly rounded posterior margin. At costal area pattern of ivorycoloured net of veins on dark ground. Stridulatory file on underside of left tegmen long, sinuous ( Fig. 58 ); teeth in the middle larger and more widely spaced than at both ends. Abdomen. Cerci long and slender with club, sinuous at apical part and decussate. Club hairy with inner part black. Subgenital plate longer than wide and tiny dot-like styli. Female. Similar to male but a bit larger. Only obtained specimen could not be preserved.