Bioacoustics of Morocera nigrifrons

Description. Small and narrow species with wings covering about abdomen ( Fig. 2B ). Face narrow elongate, black, rarely reddish, or pale with black shine ( Fig. 2E ). Without prosternal spines; mesosternal lobes rounded or angularly rounded; metasternal lobes rounded. Femora with the following number of spines on ventral margins: fore femur 4–12 anterior, 3–8 posterior; mid femur 5–13 anterior, 0–4 posterior near base; hind femur 8–11 anterior, 0 posterior (in a single male with 3 minute spinules); posterior spines on fore and mid femora minute. Hind knee lobes with one spine on both sides. Male. Stridulatory file on underside of left tegmen 1.70 mm long, with 78 teeth or 45.9 teeth per mm, about last 20 teeth very small ( Fig. 2A ). Cerci stout and conical in basal half, narrow and incurved in apical half, in sub-basal area with a straight narrow projection with obtuse end that terminates on proximal side into a small spinule, while the narrow apical area ends into a short digitiform projection that in sub-apical area is widened into a compressed semi-circular projection with a short acute spinule at distal rim ( Fig. 2C ). The titillators have about the basal half compressed and curved outward, while the apical half consists of bunches of very long hairs or bristles that are completely covered in situ by long, narrow and vaulted apical sheaths. The sheath-like cover of the titillators opens when extracted thus giving the hair bunches free ( Figs. 2D , 3H ). Female. Subgenital plate with proximal margin concave; lateral margins sub-parallel but little wavy and ascending dorsally, forming at dorsal margin convex lateral projections with stiffened rim and impressed surface; surface of plate with a transverse subbasal furrow; apical margin truncate, with a pair of stout, conical, apical projections ( Fig. 2G ). Ovipositor curved with dorsal valves in subbasal area markedly widened ( Fig. 2F ). Measurements ( 4 males , 5 females ). Body w/o wings: male 21–22, female 20.5–22.5; pronotum: male 5.2– 6.0, female 5.0–5.75; tegmen: male 11.5–12.0, female 11.5–13.0; hind femur: male 9.5–10.25, female 10.5–11.5; ovipositor: female 8.0– 8.5 mm .

Measurements. ( 1 male , 2 females in mm). body: male 21, female 21.0–21.5; pronotum: male 5.5, female 5.0–5.25; tegmen: male 11.5, female 11.5–12.5; hind femur: male 10.25, female 10.7; ovipositor: female 8.0–8.5. Stridulation. This insect produces transient pulses ( Fig. 72D ) grouped tightly together into trains ( Fig. 72A,B ) with a pulse-train period of 66.5 ms at low 20° temperatures. “Stridulatory file on underside of left tegmen 1.70 mm long, with 78 teeth or 45.88 teeth per mm; about the last 20 teeth very small” ( Ingrisch 2023 , his Fig. 2A ). The number of file teeth agree reasonably with the number of pulses in the train): mean number of pulses for 10 calls of one male 65.2. Average duration of train 19.1 ms. The spectrum is a broad band ( Fig. 72C ) between 20 and 38 kHz with an average carrier of 28.4 kHz.