Bioacoustics of Arantia (Euarantia) fasciata

( Figs. 30 A–E, 31A–F, 55A–C) Diagnostic remarks. A large, green species, with broad tegmina and hind wings slightly surpassing the tegminal apices ( Fig. 30E ). A. fasciata can be distinguished from a similar A. tanzanica by the presence on the metazona of pronotum of a light, often white patch, bordered with a black band ( Fig. 30C ). The face of individuals of this species in the Central Mozambican population is contrastingly darker than the rest of the head ( Fig. 30D ). The male cercus is slightly sinusoidal when seen from the side ( Fig. 31B ) and its apex has a strongly sclerotized dark disc ( Fig. 31C ); styli of the subgenital plate are small but clearly visible ( Fig. 31D ). Bioacoustics. Males call from treetops after dark and the call consists of short, 3–4 syllable echemes; mean syllable duration is 0.025 s (SD=0.0.0021, n=9); the peak frequency of the call is 15.2–16.9 kHz ( Figs. 55 A–C). 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.

Distribution . Widespread in Africa, from Somalia to South Africa and Gambia further west. Notes on habitat and ecology . Information on habitat and ecology are available only for East African populations (see Hemp 2005 ; 2013a , b ). A . fasciata is a night-active canopy dweller. Its song of a few loud syllables can be heard from the canopy of trees during evening hours. In East Africa it is found in savanna habitats but is also common in submontane elevations on mountains. It also occurs in anthropogenic-influenced habitats such as banana-coffee plantations and here inhabits single high trees. Nymphs are often found on broad-leaved bushes and trees of medium height. A . fasciata is fully alate often covering great distances when disturbed. However, the species seems to rely greatly on its camouflage only moving when being shaken directly from the branches.

Diagnosis . General habitus and colour pattern as in female A . fasciata , but with a smaller body size. Specimens collected in East Africa and seen in various collections differ considerably in body size. Most specimens have dark green tegmina without any pattern. However, in savanna habitats on the southern slopes of Mt. Kilimanjaro few specimens were collected with a large body size and with a vivid pattern of brown patches and fasciae on the tegmina which looked very different from the other uniformly coloured specimens. Comparing the genitalia and the stridulatory files showed that also these specimens belonged to A . fasciata . A similar situation seems to be the case in A . regina (see below) where specimens also vary considerably in body size.

Description of the male (based on East African specimens). General habitus and colour pattern. Large species with broad wings, predominantly green with a white and dark stripe on the posterior part of the pronotum. Head and antennae. Eyes oval, striped. Antennae long and thin, about 6–7 cm long. Fastigium of vertex forming a ridge with shallow sulcus above with rounded margin between antennae. Fastigium of frons conical; both fastigia separated by deep gap. Thorax and legs. Anterior margin of pronotum almost straight. Disc of pronotum almost plane with shallowly impressed sulcus on metazona. Posterior margin of pronotum slightly down-curved, broadly rounded. Broad based, short, blunt knob (reduced spine?) on fore coxa. Tympana of fore tibiae on both sides closed or closed on outer side and on inner side triangular shaped or longish oval. Fore femur unarmed or with few tiny, sometimes black tipped spines. Mid femora unarmed. Hind femora with two rows of small evenly spaced spines, black tipped with broad base. Distally 1–2 spines can be larger to very large in some specimens with flange-like bases. All femora with two pairs of spurs at apex. Fore and mid tibiae with two ventral rows of few small spines, a pair of spurs at the apex. Hind tibiae with four rows of spines, dorsal rows of spines very dense, especially distally; three spurs at each side at apex. The stridulatory file is curved and consists of ca. 100 evenly spaced teeth ( Figs 55– 56 ). Abdomen. Cerci slightly curved, decussate, long with a stouter base and more slender anterior part, tips clubshaped with a serrated sclerotized ridge ( Figs 85a, 85b ). Subgenital plate longer than wide, with median ridge and tiny styli.

Remarks . A . fasciata is distributed over a large area of Africa south of the Sahara. Specimens studied from West , East and South Africa show a certain degree of morphological variation suggesting that at least different populations are present. Thus there are differences in the shape of the fastigium verticis, the shape of the tympana on the fore legs ( West African species with completely closed tympana on both sides while in specimens from East Africa the inner side is more open, being tri-angular shaped and more open on the posterior side). Also the shape of the subgenital plate varies slightly. Further in West African species the face is smoother with parallel furrows below the eyes running to the labrum, while in East African specimens the facial area below the eyes is strongly wrinkled. However, the morphological variation is so gradual that no clear differences can be put down to define species. Unfortunately no male specimens from West Africa are stored in any museum we have visited and since females are generally morphologically very similar in Arantia ssp. it cannot be excluded that West and Central African populations differ from East and South African populations on species level. More collecting hopefully will eventually clarify the status of the Arantia fasciata species-complex and molecular analyses and studies on song should be undertaken to illuminate speciation patterns.

Remarks. When studying the specimen material in the NHM London, UK , it became clear that A. spinulosa Brunner, 1878 is synonymous with Arantia fasciata . This is based on material identified by P. M. Stock 1960, D. Ragge 1962, J. Huxley 1972, L.M. Pitkin 1973, and J. Marshall 1982. Thus the record of A. spinulosa by Kevan (1955) from Kilimanjaro (Makoa) refers to A. fasciata . Probably due to its wide distribution A. fasciata shows some morphological variation in terms of colouration, size and slight differences in the genitalia. Molecular analysis and studies on song should be undertaken to shed light on the status of this species. On Mt Kilimanjaro savanna specimens are of much lighter colour with different patterns of brown mottles or fasciae on the tegmina while individuals collected from the submontane plantation belt were always uniformely dark green ( Fig. 8 A).