Bioacoustics of Macrogryllus bicolor

Description. Male (nov.). General appearance somewhat similar to that of M. ephippium and M. canorus sp. nov. , but body distinctly smaller, and coloration other ( Figs 34, 35 ): head yellowish to light brown with reddish tinge, whitish ocelli, greyish or greyish brown eyes, short brown stripe on epicranium along clypeal suture, a pair of small brown oblique stripes between antennal cavities, somewhat darkened small areas under eyes, greyish brown antenna with light brown or yellowish scape and pedicel, and light brown or brown mouthparts having brown median spot or light brown lateral spots on upper half of clypeus, three narrow whitish stripes on lower half of clypeus and sometimes somewhat darkened marks on labrum and on proximal parts of mandibles (palpi in both specimens light brown); pronotum uniformly black but with a pair of small dark reddish brown marks on disc; legs light brown but sometimes with slightly darkened subapical part of hind femur and base of hind tibia as well as some spines and spurs of hind leg; tegmina greyish with semitransparent membranes in stridulatory apparatus, barely darkened basal and apical areas in dorsal field, and greyish brown lateral field having area between R and M as well as short basal stripe along costal edge slightly lighter; rest of body light brown to almost yellowish with greyish brown abdominal tergites, anal plate, paraprocts and cerci (genital plate sometimes with slightly darkened apical part). Shape of head and pronotum similar to that of M. ephippium and M. canorus sp. nov. , but pronotum slightly less widened in posterior part (for comparison see Figs 34 and 42 ); outer tympanum almost thrice as long as wide and slightly longer than width of fore tibia in tympanal region; inner tympanum much smaller (outer tympanum approximately twice as long and wide as inner one); hind tibia with 5–6 outer and 5–6 inner dorsal spines (these spines rather short and similar to those of M. canorus sp. nov. in structure); tegmina reaching abdominal apex, with four oblique veins, with mirror barely longitudinal and having one dividing vein ( Fig. 34 ) but sometimes two such veins, and with 13–15 branches of Sc (three or four distal branches more or less S-shaped and starting from Sc stem; other branches almost straight to somewhat arcuate, but two or three of them starting from proximal half of Sc stem) and sparse crossveins in lateral field; hind wings distinctly not reaching tegminal apices; genitalia as in Figs 36–38 (their ectoparamere rather similar to that of M. canorus sp. nov. but with lateral edge more concave than in this species and less concave than in M. ephippium , and with posterodorsal sclerite wider than even in M. ephippium and without distinct apical lobule; see Figs 22–24 and 25 ). Female . Judging by original description ( Chopard 1930 ), holotype (female) from Sarawak State of Malaysia ( Borneo ) almost indistinguishable from above-mentioned males in size, coloration and other non-sexual characters, but its tegmina completely black, with nine longitudinal veins in dorsal field and four branches clearly starting from Sc stem in lateral field, and with rather short ovipositor (hind femur approximately 2.7 times as long as ovipositor) . Length (mm). Body: male 23–24, female 29; pronotum: male 4.7–5.0, female 4.5; tegmen: male 15.5– 17.0, female?; hind femur: male 14–15, female 16; hind tibia: male 7.3–7.5, female 8; hind basitarsus: male 3.7–4.0, female?; ovipositor 6. The measurements of female are given according to Chopard (1930) .