Bioacoustics of Zabalius ophthalmicus

Distribution and natural history. Z. ophthalmicus is widely distributed in sub-Saharan Africa, from the Democratic Republic of the Congo , through Angola , Zambia , Kenya , Tanzania and Mozambique , to South Africa and Namibia ( Beier 1957 ; Hemp 2013a ; de Jong 1960 ). In Mozambique this species is associated with habitats that provide tall, broad-leaved vegetation, including banana plantations, from the lowlands to sub-montane elevations. It is not uncommon to hear the call of Z. ophthalmicu in an urban environment as long as it contains tall trees. Typical of other members of the tribe Pseudophyllini , these nocturnal katydids spend the day resting on the underside of large leaves, with their wings partially spread and tightly pressed against the surface of the leaf ( Fig. 23E ). Measurements ( 3 males , 3 females ). body w/wings: male 58–64 (60.73.1), female 75–80 (772.6); body w/o wings: male 36–39 (371.7), female 39–41 (39.71.2); pronotum: male 8–9 (8.7.6), female 9–11 (101); tegmen: male 49–51 (501), female 63–65 (64.31.2); hind femur: male 16–17 (16.3.6), female 19–20 (19.3.6); ovipositor: 16–17 (16.3.6) mm.

( Figs. 23 E–H, Figs. 57 D–F) Diagnostic remarks. A large, vividly green katydid with characteristically bright blue hind femora ( Fig. 23F ). The pronotum is covered with conspicuous, usually orange tubercles and the eyes display a contrasting, vertical striation ( Fig. 22H ); a similar striation is also seen in species of Arantia Stål and several other Phaneropterinae but they all lack the pronotal tubercles. The subgenital plate of the male is extremely narrowed in its posterior part and carries a pair of flattened, leaf-like styli ( Fig. 23G ). Bioacoustics. Males of Z. ophthalmicus call from high in the trees, usually at least 5 m above the ground, and are difficult to spot. Their call is a bell-like, nearly pure-tone series of short, 0.18– 0.28 s echemes, each consisting of 4–6 syllables; mean syllable duration is 0.02798 s (SD=0.00454, n=52); the peak frequency of the call is 6.4–8.3 kHz ( Figs. 57 D–F). The call is easily audible to the human ear from at least 50 meters away.