Song Structure and Description of Some Costa Rican Katydids (Orthoptera: Tettigoniidae)

The physical features of the calling songs of a dozen species of Tettigoniidae from Costa Rica are recorded and analyzed. A new species, Cocconotus pusillus, is described from the cloud forest.

Several forms from the understory of lowland rainforest utilize high-Q (sinusoidal) carrier frequencies in the ultrasonic range and to this end the sound generating regions of the tegmina are uniquely strengthened. Relative to other katydids, these insects show what may be adaptations for avoidance of predatory bats: elongate antennae, lowered thresholds for elicitation of defensive behaviour and a severely curtailed signal emission time. It is proposed that reduced signal dura tion has placed a selective premium on localization efficiency during pair formation. The ultrasonic pure tone carrier, functioning in conjunction with highly directional ear slits, may be an adaptation to enhance localization.