Intraspecific and interspecific variation in drumming signals in the genus Capnioneura (Plecoptera: Capniidae)

The male drumming calls of four species of the genus Capnioneura, and for the first time, the female answer signal from one species of this genus are described. Only the male call of C. mitis from a southern Iberian Peninsula is known. In the current study, the male calls of three additional C. mitis populations from two different mountain drainages and the male calls of C. gelesae, C. libera and C. petitpierreae are described and analysed. The calls were near-ancestral and percussive signals with variable numbers of beats and approximately constant, monophasic beat intervals. The mean interbeat intervals were species specific, ranging from 250 to 1500 ms. The C. mitis female answer interbeat intervals were similar to the call but composed of 3–4 beats. Intraspecific and interspecific variation is discussed and these results support the hypothesis that stonefly drumming plays an important role as a reproductive isolating mechanism.