Chorthippus (Chorthippus) lacustris La Greca & Messina, 1975

Calling song (Figs 40–41, 45–46) The male of Ch. lacustris produces 3–4 calling songs, each lasting 450–500 ms and separated by intervals of about 2 s. In contrast to other species of this group, when producing a calling song, the leg movements in lacustris are very irregular and the amplitude of the leg movements greatly varies. As a result, the ampli- tude and duration of sound pulses varies as well.

Courtship song (Figs 72–74, App. 2) This species has the most remarkable courtship song among all members of the group because of its highly complex visual display. This conspicuous visual display was described in detail by von Helversen (1986). As usual in this group, the song starts with an alternation of A and B elements. The leg movement pattern producing A and B elements resembles that in Ch. oschei . During the A element, the legs vibrate more rapidly at a rate of about 40–45/s, during the B element, the legs are vibrated more slowly at a rate of about 14/s. Oscillographic analysis shows that sound is only produced during A elements, which consist of the pulses repeated at the rate of leg vibra- tions. After about 35–40 alternations of A and B elements, a complex of B1-A1-C elements follows. In contrast to other species of the group demonstrat- ing the visual display, lacustris starts with lifting of its abdomen already during the B1 element. Then the A1 element follows, when the legs produce extremely low-amplitude vibrations at a very high rate of about 90/s, and after that, the first stroke with the tibiae follows. Then the femora go down but the legs straighten out even more. After that, the legs are slightly folded up and produce the second stroke with the tibiae. During about 2 s, the abdomen is kept in a lifted posture. The abdomen is lifted at a maximal angle of about 70°, whereas the maximal angle between femur and tibia is 140° on average. After that, the tibiae come to their normal position and the legs vibrate with small amplitude at a rather high rate of 80–85/s. The B1-A1-C complex repeats 4–5 times, and A/B pairs alternate again. Oscil- lographic analysis shows that the loudest elements of the song are A1 and C elements. In general, the courtship song of lacustris is much quieter than the songs of other species of the group. [1]

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