Resonant sound production in Copiphora gorgonensis (Tettigoniidae: Copiphorini), an endemic species from Parque Nacional Natural Gorgona, Colombia

Abstract

This article describes the acoustic characters of Copiphora gorgonensis, a new species endemic to Gorgona Island National Park, Colombia. It is closely related to C. brevicauda, a congener distributed in the Pacific rainforest of Ecuador and Colombia, and also reported in Central America and other countries of northern South America. Here we provide diagnostic characters for identification; we study the mechanics of stridulation using laser vibrometry and optical motion detectors. Distinguishing features include: the highly tonal song of males with a carrier frequency peaking at 23 kHz; pulses repeated with a high rate of nearly 50/s and wing motion exhibiting a typical subsinusoidal pattern, as has been described for other Copiphorini. The natural frequency of the right forewing is close to that of the calling song and the wing-motion patterns indicate that sound vibrations are the result of sustained tooth impacts, corresponding to the natural frequency of wing vibration, i.e., the tonal characteristic of the calling song in this species is the result of resonant stridulation. This resonance, and the amplitude component of the song, are attributed to the mirror frame and its surrounding cells and veins. These results are contrasted and discussed in regard to published literature on tettigoniid stridulation.