Bioacoustics of Acantheremus colwelli

Diagnostic description.— Body small, with wings in both sexes slightly surpassing apices of hind femora ( Figs. 10 A, 36C). Fastigium of vertex about 2.5-3 times as long as eye diameter; triangular when viewed in front; apex bifurcated ( Figs. 10 B-C). Pronotum granulate; both anterior and posterior margins straight; lateral lobe of pronotum 1.8 times longer than high. Male stridulatory apparatus well developed; stridulatory file straight, 1.15 mm long, 0.17 mm wide, with 358 very closely spaced, lamelliform teeth ( Figs. 43 D-E); transparent area between M+CuA and mirror in shape of equilateral triangle, mirror about as long as high. Caudal margin of male 10th tergite weakly emarginated. Male cercus almost straight when seen from above, its apex strongly bent downward, ending in sharp spine; inner, ventral part of cercus with short spine ( Figs. 10 E-F). Female cercus simple, elongately conical. Male subgenital plate about 1.3 times as long as wide, distinctly narrowed toward apex, apex with narrow, almost parallel sided incision, reaching past 1/3 of length of plate; styli short, about 1.8 times as long as wide ( Fig. 10 G). Female subgenital plate about 1.5 times as wide as long, apical part of plate narrowed and shallowly incised ( Fig. 10 D). Ovipositor shorter than hind femur, ratio tegmen/ hind femur 0.9, distinctly upcurved in its basal part ( Fig. 10 A). Coloration .— General coloration green ( Fig. 36 C) (yellow in old museum specimens). Lateral carinae on the head, knees, and cubital veins of tegmina yellow with red edges; femoral spines often red; proximal end of middle tibia with dark brown, longitudinal spot; apex of ovipositor dark brown. Measurements (mm). — Body (excl. tegmina): male 26, female 26-30; body (incl. tegmina): male 30, female 36- 40; pronotum: male 7, female 7.5-8; tegmen: male 19, female 25-28; hind femur: male 12, female 14.5-16, ovipositor 13-14. Bioacoustics.— The call of A. colwelli consists of irregular series of short, buzzing trains, lasting 0.50- 1.28 s , separated by 233-262 ms long pauses (at 25°C). Each train consists of 34-89 individual wingstrokes ( Figs. 54 D-E). The call is low Q, without a clearly defined energy peak. It is likely, however, that most energy is allocated in ultrasonic frequencies, which I was unable to record due to the technical constraints of the recording equipment.