Bioacoustics of Subria sylvestris

Diagnostic description.— General characteristics as described above. Male pronotum short, barely covering basal half of stridulatory apparatus ( Fig. 33 B). Tegmina surpassing apices of hind femora by about 1/3 of their length ( Fig. 33 A, 36H) (in one female from La Selva Biological Station tegmina are abnormally long, surpassing the apices of the hind femora by more than half the length of the tegmen). Stridulatory file of male weakly curved, 2.1 mm long, with 170-179 (n=3) wide and thin teeth, maximum width of file 142 μm ( Fig. 51 A); teeth of file uniform in thickness, evenly spaced and smoothly narrowing towards proximal end. Male cercus weakly incurved, with incised apex, and large, blunt, ventral tooth subapically ( Fig. 38 D). Ovipositor distinctly curved upwards and slightly widened midlength, slightly longer than half of hind femur (ratio ovipositor/hind femur 0.65- 0.74) ( Fig. 33 J). Coloration — Unlike other species of the genus, S. sylvestris exhibits a remarkable color dimorphism, having both green and brown ( Fig. 36 H) color morphs occurring within the same population. The material examined included 35% of brown individuals and 65% of green ones (including olive green ones). There seem to be no correlation between the color and season or geographical distribution. Most individuals of the species lack a wide, dark band on the pronotum, typical of the remaining two species of the genus. Instead, the sides of pronotum have two, thin, white or light brown stripes. Occasionally the brown band, or intermediate stages are present. Tegmina often have several irregularly distributed, diffused dark spots. The outer pagina of the hind femur may or may not have a distinct reticulate pattern (the pattern is present in most brown individuals but is only rarely distinct in green ones). Measurements.— Table 25 . Bioacoustics.— The call of S. sylvestris is low duty, with sound production accounting for only about 14% of the calling cycle. It consists of short (147-175 ms) phrases produced at intervals of 0.85 - 4.0 S , each phrase consists of two short (38 - 78 ms) pulses ( Figs. 58 C-D) (all data apply to songs recorded at temperature 26½C). Typical of most Tettigoniidae , it is a low Q call, with most energy allocated between 6 and 12 kHz in the audible range, and above 20 kHz (the upper frequency range of the call is unknown because call components above 22 kHz were not recorded due to technical constraints of the equipment used). Males start calling at dusk and continue probably all night. Calls are undetectable in field conditions, even on relatively quiet nights. In laboratory conditions the calls are audible from a distance of about 1-1.5 m .