Figure 4 from: Graf W, Konar M, Murányi D, Orci K, Vitecek S (2014) A new species of Isoperla (Insecta, Plecoptera) from the Karawanken, with considerations on the Southern Limestone Alps as centers of endemism. ZooKeys 448: 27-36. https://doi.org/10.3897/zookeys.448.8509

Figure 4 - Oscillograms showing the drumming call of an Isoperla claudiae sp. n. male (ambient air temperature 24.2 °C). A oscillogram showing rhythm and amplitude variation patterns of a call B a faster oscillogram of two bi-beats from the second half of the call C variation of interval duration between bi-beats during the call presented in A. Inter-beat intervals were measured from the amplitude peak of one bi-beat to the amplitude peak of the next bi-beat (measured on the same call presented in A).