Ancistrocercus (Ancistrocercus) circumdatus (Walker, 1870)

La Pacifica has a relatively dry climate and A. circumdatus was the only nocturnal katydid taken there. But it was abundant, sing ing from the foliage of trees near the cabenas. Specimens were located by their singing and could sometimes be reached from the ground. In a nearby forest these same insects were discovered tak ing diurnal refuge in axils of the spiny leaves of large (2m high) terrestrial bromeliads. The frons of both sexes is marked turquoise-green and this darker colour may help to conceal the in sect as it faces skyward within the shadow of the leaf base. The male is 3-4 cm in length; females are slightly larger. The ovipositor is prominent and shaped like a bayonet. The body is broadly cream yellow marked with much brown. Dark brown veins contrast against the cream-white archedictyon of the tegmina. The song is a series of longish ticks. At 22 C in the laboratory one male employed a tick rate of 8/s. What the human ear discerns as a mere tick is actually a very elaborate AM pattern (Fig. 9). Both sinusoidal and complex wave pulses are tick components. By calculation from high speed AM traces, the sinusoidal pulses are seen to be responsible for the pronounced spectral peak near 32 kHz (Fig. 2). A longer somewhat incoherent train of rapid-decay pulses begins each tick. This is followed by 3 trains of the 32 kHz sinusoidal pulses, each train interspersed with a rapid-decay pulse train. [1]

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