Five species of neotropical Ponerinae ants, Ectotomma permagnum Forel, E. quadridens Fabr., E. ruidum Roger, E. tuberculatum Olivier and Pachychondyla apicalis Latreille, were studied. The genus Ectotomma, consisting of 14 species in the tropical forests of Central and South America, has been studied previously in relation to the stridulation organ only. Stridulations were heard, in the four species considered in this paper, during artificial disturbance of individuals or of the whole colony; so the role of sound production during normal life is still uncertain. Pachychondyla apicalis, belonging to Central American forests, is occasionally present in cocoa and coffee plantations. The recordings made under laboratory conditions revealed the emission of pulse trains with very clear pulses extending in frequency to more than 75 kHz. The sounds recorded from the workers of the genus Ectotomma appeared homogeneous in their acoustic structure. They were typically emitted in long sequences and were made of pulse-trains consisting of two subunits (disyllabic chirps) characterized by pulses with opposite phase, produced by the alternate movement of the simple plectrum against the pars striders. In sounds recorded from workers of Pachychondyla we found sequences of monosyllabic chirps, made by single trains of pulses. Pictures and measurements on the stridulatory apparatus were made with a scanning electron microscope.
stridulation, ultrasonic, ants, Ectatomma, Pachychondyla