Bioacoustics of Conocephalus (Anisoptera) cinereus

Remarks.— Conocephalus cinereus is known from most of the Caribbean islands and a large portion of the continental Americas, from Florida in the US and Vera Cruz in Mexico , through Guatemala , Costa Rica ( Map 1 ) and Panama , to French Guyana , Surinam and Peru . Older records (prior to Rehn and Hebard 1915b ) should be treated with caution as this species has been frequently confused with C. fasciatus (De Geer) . These two species can be separated based on the shape and coloration of male cerci (cerci green, apical part short and only weakly flattened dorso-ventrally in C. fasciatus [ Fig. 38 D], yellow, apical part more elongated and strongly flattened dorso-ventrally in C. cinereus [ Fig. 38 F]) as well as in the number of the stridulatory teeth (about 33 in C. fasciatus , 44-45 in C. cinereus ). In addition, the apical portion of the fastigium of vertex in C. cinereus is usually slightly expanded laterally, whereas that of C. fasciatus has its sides parallel.

Coloration .— Coloration typical of the genus, light green, with brown stripe on top of head and pronotum; posterior half of abdomen in male bright yellow, cerci yellow to light brown; abdomen in females usually green or faintly yellowish ( Fig. 37 D). Measurements .— Table 2 . Bioacoustics.— The call of C. cinereus has two repeating, distinct parts: a series of individual, short chirps, followed by a train of continuous buzz ( Fig. 52 E). At 27°C each series of chirps lasts 1.6- 1.8 s , with chirps produced at the rate of 0.30-0.32/s, and each chirp lasting 32-37 ms (avrg. 34±1.7 ms, n=10) ( Fig. 52 F). The continuous portion of the call lasts 0.86- 1.1 s and consists of a train of short chirps produced at the rate of 39.5-40.2/s ( Fig. 52 G). Both parts can be repeated continuously for several minutes. Within the audible portion of the call most energy is allocated between 8 and 16 kHz.