Bioacoustics of Mikrischyrum musicum

Measurements (male/female): pronotum 5.5/ 5–5.5 mm , tegmina 12/ 18 mm , hind femora 8/ 10 mm , male subgenital plate with styli 3.5 mm , ovipositor almost 10 mm . Comparison with the two other species: The male holotype of M. festae is slightly larger and has a narrower pronotum, which is posteriorly hardly widened, with a slightly bilobed rear margen. It has only two white spots, widely separated on the corners of the rear margin (photos in Cigliano et al. 2021 ). The hind femora have 6 spinules ( Griffini 1896 ). The male of M. minutum is considerably smaller than the new species and has conspicuously long spines on the inner genicular lobes of the fore femora and the outer ones of the hind femora (about as long as dorsal width of the femora, Fig. 5 in Nickle 2006 ). The hind femora have 5–7 spinules (op. cit.). The male subgential plate has a very narrow terminal emargination (width and depth less than the width of the styli (op. cit. Fig. 26). Males of that species have a prominent trapezoidal whitish median spot on the frontal margin, and a very large one coating the entire metazona. In the holotype the frontal spot and the coated metazona are connected by a narrower whitish band, which is more weakly developed in the paratype (op. cit. Figs. 5, 24). Calling song: The males produce at night extraordinarily long pulse trains of around 2 seconds (20°C, holotype in cage, Fig. 3A ) to over 3.5 seconds (13°C, field recording, Fig. 3E ). Independent of temperature they consist of around 15 pulse groups, each comprising 2–4 sustained pulses. The carrier frequency spectrum shows a very narrow peak just above 20 kHz and beyond human hearing range ( Fig. 3C ). The long pulses, almost pure sine waves, involve a slight frequency modulation ( Fig. 3D ). Probably sound is produced during closing strokes of the tegmina, with the low-amplitude signals preceding the pulses corresponding to the opening strokes ( Fig. 3B ). Note to Braun 2002 : The recording used for Fig. 6.3.3 “ Drepanoxiphus ?“ seems to have a technical issue: the redigitized copy shows a faint periodic background signal and the peak appears a little bit below 20 kHz, as in that figure. In the other recordings as well as the field recording it is above 20 kHz.