Bioacoustics of Nothochodaeus huxleyi

Description. Holotype male ( Fig. 6–8 , 11, 13 , 16 ). Length: 11 mm (from the apex of the mandibles to the apical part of the tergite VIII). Width: 5.9 mm (greater width of the pronotum). Head : Head transverse, sub-hexagonal, entirely orange except for the frontoclypeal carina which is darkened. Frontoclypeal carina strongly raised, in inverted “U” shape, ended on both sides by a small, well individualized tubercle ( Fig. 6 , 16 ). Clypeus trapezoidal in outline, strongly obliquely sloping forward, the anterior margin finely denticulate, the interval between these small denticles with a small yellow-orange bristle directed forward. Posterior declivity of clypeus relatively abrupt behind the carina, flanked on both sides by the clypeofrontal suture, slightly impressed and extending laterally up to the level of the anteromedial angle of the eye. Head surface shiny, covered with tight but not contiguous medium setiferous granules; a median longitudinal area, smooth, from the base to the middle of the head in front. Labrum transverse, dorsally convex, hyaline, long pubescent, strongly emarginate in the middle front, with a distinct raised transverse ridge in the middle. Eyes moderate in size, globose, strongly produced laterad with spaced long setae along their inner edge. Mandibles subequal, falciform, slightly concave dorsally, the surface matt, distinctly wrinkled on a microreticulate background. Mentum oblong, subquadrangular, weakly depressed in front. Antenna 10-segmented, the scape and funicle yellow-orange, pubescent, the club shiny, dark-brown except for narrow whitish apical part. Pronotum: Transverse, strongly convex, entirely margined, distinctly emarginate behind the head with a thin hyaline membrane in front, the lateral edges and base fringed with setae. Front angles prominent, projecting forward, the posterior ones obtusely rounded. Pronotal surface with a very dense punctation, consisting of small, tightly packed, medium-sized setiferous rounded granules with yellow-orange setae erect upwards. The setae located laterally at the front angles distinctly longer, black, curved upwards. A short median longitudinal furrow at basal third, extending forward to the anterior margin as a thin, darkened line. Pronotum uniformly orange with two black paramedian spots along the front margin, two other spots more broadly spaced along the base, and a distinct darkened fovea in the middle of each side. Elytra: Transverse, dull, densely pubescent, their color coarsely similar to that of the pronotum. Striae well-marked, relatively shallow, consisting of aligned sunken medium points separated by about 1–1.5× their diameter. Intervals almost flat, punctation strong and tight consisting of small setose granules on a microreticulate background, the minute setae erected, distinctly darkened. Humeral callus well developed. Elytral color patterns as follow: a thin transverse dark band on the fourth interstria along the front margin, a round black spot located on the humeral callus and a transverse median dark band interrupted in the middle, merging laterally with the next band located in the apical third of the elytra. Scutellum elongate, triangular in outline, the lateral edges darkened, the disc slightly depressed longitudinally in the middle. Abdomen: Strongly convex with six visible ventrites (III–VIII). Surface smooth, shiny, microreticulate; ventrites with minute setigerous tubercles along their front margin, the disc with medium setae roughly aligned. Tergite VIII (pygidium) brownish-black, pubescent, the punctation consisting of small close setose granules embedded on a microreticulate background; a lightened transverse band along the upper edge. Tergite VII (propygidium), entirely orange with trapezoidal interlocking mechanism. Stridulatory apparatus (sternite VI) present. Legs: Protibia quadridentate externally, the median tooth (third) barely visible, the basal tooth very reduced, spinose, pointed; inner apical angle of protibia with a short, acute pollex directed anteriorly ( Fig. 18 ). Femur without accessory teeth, their surface with two parallel rows of setose punctures. Genitalia: Aedeagus with phallobase dorsoventrally curved, acuminate apically; parameres short, symmetrical, distinctly divergent at apex, the apical lobe ovoid. Endophallus well developed, unarmed (lacking endophallites) ( Fig. 11 ). Sexual dimorphism. The female paratypes show little variation from the male, and negligible sexual dimorphism. The area located behind by the clypeofrontal carina is flat-topped within the female, somewhat reminiscent of the clypeal horn of males of the genus Ceratochodaeus Huchet, 2017 (this area is obliquely truncated backwards within the male). Finally, overall body coloring of the female may appear distinctly darker than in males (notably the underside, entirely dark orange-brown within the female allotype whereas it is entirely pale yellow in male holotype , except for the abdomen, partly darkened). Similar color variation patterns between both sexes have been reported for the close species N. borneensis ( Ochi et al. 2013 ) .