Bioacoustics of Decticus albifrons

Redescription. Lateral lobe of pronotum about 1.5 times higher than wide; anterior margin inclining backward, posterior margin vertical, and ventral margin circular. Mirror irregular ellipse ( Fig. 6i ). Stridulatory file with about 72–75 widely regularly-arranged pegs; pegs gradually becoming smaller towards both ends ( Fig. 6j ). Male ninth abdominal tergum slightly extending backward with an obtuse angle. Male tenth abdominal tergum with an oval central concavity on dorsal surface; apex shrinking with a shuttle-shaped incision. Male epiproct covered by tenth abdominal tergum, bent down at an angle of 90° ( Fig. 4f ). Male subgenital plate with distinct lateral carinae. Generally brown, scattered with black and white spots. Face light purple, darkening to both sides. Clypeus pale yellow. Areas around eyes and antennal socket yellow. Occiput brown. Pronotum dark brown; center of pronotal lateral lobes dark brown, becoming black and yellow outwards. Tegmen creamy-brown, scattered with creamy-yellow and black spots. Hind femur black marbled on posterior surface, and brown on ventro-anterior surface. Yellow with the ventral of body. Song. The calling song consisted of stereotyped chirps with a regular period (147.47±6.75 ms) and duration (104.69±4.46 ms) ( Fig. 7 a–c). Each chirp was comprised of 2 syllable groups. Frequency ranges from 0 to 24 kHz, frequency of main peak is about 8.79 kHz, and that of second peak is not significant ( Fig. 7 d–e). The important parameters are listed ( Tab. 3 ). Measurements (mm). See Table 6 and Table 7 .

The loud calling song, a common Mediterranean sound in hot, sunny weather, is a long series of click-like syllables, sometimes repeated fairly regularly at the rate of about 5-7/s, or, if less regularly, usually with a mean repetition rate within this range. Depending partly on temperature, the mean repetition rate is occassionally as low as 2/s or as high as 10/s. The interval between successive syllables is usually within the range 0.1-0.4s, but is sometimes under 0.1s and occassionally as long as 1s a little more. The song continues for indefinite periods, often of many minutes. Oscillographic analysis shows thatnearly all (occassionally all) the sound is produced by the closing stroke of the fore wings, each closing hemisyllable lasting about 6-10 ms. The song is resonant, the audible sound produced being an almost pure tone of about 8-9 kHz (see Fig. 257).

The song of the male found in Montemor-o-Novo ( g. 2) differs from that of the males collected in italy (schmidt 1996a, abb. 12). The loud calling song consisted of a series of very short syllables, sometimes repeated fairly regularly, at a rate of about 16/s at relatively high temper- atures. The interval between successive syllables was very short (about 30-110 ms). The song continued for inde nite periods, often for many minutes. The oscillographic analysis showed that diplosyllables were emitted. The opening stroke is always faint and clear, but the audible sound is produced by the closing stroke of the elytra. The loud part of the hemisyllable lasts for about 5 ms. Ragge & Reynolds (1998) also report- ed some differences in the songs of males collected in france.