Bioacoustics of Tritonus

Description. Form narrowly to very broadly oval. Head. Systematic punctures present on the lateral margins of the clypeus and frons; absent or undetectable on the labrum. Ground punctation fine to coarse; not uniform in size. Labrum small, often retracted beneath or not extending beyond the anterior margin of the clypeus such that it is not visible from above. Mentum quadrate ( Figs. 2 b, 3b), slightly depressed at lateral margins; often with fine to coarse microsculpture consisting of fine transverse microreticulation. Maxillary palps very short, always shorter than width of labrum; apical segment longer than penultimate ( Fig. 14 ). Antennae 9-segmented, including a 3-segmented pubescent club. Dorsal surface of the eyes not bulging, in the same plane as the surface of the head. Thorax. Pronotum with systematic punctures forming anterolateral and posterolateral series; each series forming an irregular arc or row; systematic punctures larger than ground punctation. Posterolateral corners of pronotum rounded, never angulate or spinose. Prosternum ( Figs. 7–8 ) with a low median carina which may be fine and without a strong ridge ( T. steineri ), or more commonly, strongly ridged ( T. complanatus , T. cribratus ). Mesoanepiplerual sutures straight, giving the mesoventrite a diamond-shaped appearance ( Fig. 6 ). Ten very fine rows of elytral serial punctures are distinct in T. complanatus , but not discernable (or absent) in the remaining species, although some rows of coarse punctures may represent serial punctures in addition to systematic punctures. Five rows of elytral systematic punctures present although frequently difficult to distinguish from enlarged serial punctures in some species (e.g. T. complanatus ). Elytra with sutural stria at least in posterior half ( Figs. 4–5 ). Interior of elytra with a small roughened region (=plectrum; Fig. 10 ) along the central margin. Procoxae ( Figs. 7–8 ) finely pubescent, without thickened setae or spines. Hind femora entirely glabrous ( Fig. 13 ). All tarsi with five segments. Meso- and metatarsi with two rows of ventral spicules and a dorsal row of fine setae. Abdomen. Abdomen with five exposed ventrites ( Fig. 11 ). Abdominal ventrites 2 to 5 each with median glabrous region, varying in width and length; ventrite 1 often with a small, posteromedial glabrous margin, but not as extensive as the region of the other ventrites. Anterior margin of ventrites 3 and 4 sometimes slightly to strongly crenulate. Ventrite 5 entire, without apical emargination. Laterosternite 3 with a distinct, ridged stridulatory file ( Fig. 9 ). Aedeagus of the simple tri-lobed type , with parameres and median lobe generally unmodified.