Acoustic emission in Megatrupes cavicollis (Bates 1887) (Coleoptera, Geotrupinae) [abstract]

C. Palestrini, M. Luzzatto, A. Roggero and M. Zunino (1997). Acoustic emission in Megatrupes cavicollis (Bates 1887) (Coleoptera, Geotrupinae) [abstract]. Bioacoustics, Volume 8 (3-4): 263 -264

The genus Megatrupes Zunino 1984 is up to now represented by two species, M. cavicollis mates 1887) and M. fisheri (Howden 1987), both distributed between the western Sierra Madre and the Sistema Volcànico Transversal, in Mexico. The aim of our research is to analyze the sound produced by M. cavicollis through two distinct apparatuses - thoraco-elytral and coxo-abdominal. The individuals examined were collected during the summer of 1987 at the Reserva de la Biosfera "La Michilia'', Durango, Mexico. Signals were recorded, acquired and analyzed through the program Signalize 3.12. Each emission consists of a disyllabic chirp, with two distinct sub-units separated by a pause. This is a standard situation among the Geotrupinae. Seven variables concerning duration and frequencies of the chiro have been analyzed. The sexual dimorphism, as regards the morpho-anatomy, does not appear in the acoustic context. Both apparatuses contribute to the sound production. Nevertheless, the coxo-abdominal apparatus seems to be more effective than the thoraco-elytral. Individuals deprived of the elytra emitted stridulations very similar to those usually produced by individuals not experimentally constrained, whereas individuals deprived of their hind legs emitted very thin, unrecognizable sounds. Although statistical analyses of frequencies and duration show significant differences among individuals, males and females do not appear to be separated into two distinguishable clusters.