Bioacoustics of Monseremus

Description. Head: Face not particularly large; in frontal view roughly oval; forehead nearly smooth; fastigium verticis distinctly wider than scapus; medium and lateral ocelli small, little distinct ( Fig. 79H ). Abdominal tergites two and three each with two little distinct rows of minute stridulatory pegs (4, 11; 15, 6; n=1; Fig. 79L ). Wings absent ( Figs. 78 E–G). Legs: Fore coxa with a rather long spine at fore margin; fore and mid femora unarmed; fore and mid tibiae with four pairs of large ventral spines and one pair of smaller ventral spurs; hind femur with 5–6 external and 8–10 internal spines on ventral margins, little increasing in size towards posterior end; hind tibia with spaced spines on both dorsal margins increasing in size from base to end; ventral margins with one pre-apical spine each; with 3 apical spurs on both sides. Coloration. General color medium to dark brown, dorsal side darker than ventral side; with little distinct darker ornaments on hind femur. Face yellowish brown. Male unknown. Female. Seventh abdominal sternite with a strong convex apical extension having a fallen-T shaped elevation in middle and is grooved on both sides; main part with two pits in about half length of sternite, one at each side. Subgenital plate basic shape roughly semi-circular with rim strongly swollen, basal margin straight in middle but on both sides with a large swollen extension bent ventrad and later craniad, tip broadly rounded ( Figs. 79 I–K). Base of ovipositor laterally at very base with a conical protuberance. Ovipositor straight, longer than hind femur; tip narrowly obtuse ( Fig. 78 F–G). Measurements ( 2 females ).—body w/o wings: 23–24; pronotum: 5; tegmen: 0; hind femur: 14; antenna: 150; ovipositor: 17.0– 17.5 mm .

Remarks. The two species are very similar in general morphology, size and colouration in both males and females. Only the female subgenital plate and male tenth abdominal tergite show clear-cut species differences ( Fig. 2 ). The female tenth abdominal tergite and epiproct did not exhibit species differences ( Fig. 3 ). The number of pegs on the two stridulatory files on each of the second and third tergites can be variable within species (second tergite ♂ ♀ 4–6, ♂ ♀ 12–14; third tergite ♂ 12–14 and ♀ 15–17, ♂ ♀ 16–19 in Monseremus bellus comb. nov. [n = 4♂ , 4♀ ]) and do not appear show clear species differences ( vs. ♂ ♀ 4–5, ♂ ♀ 11–13; ♂ ♀ 15–17, ♂ ♀ 16–18 in Monseremus appendiculatus [n = 2♂ , 2♀ ]) ( Fig. 3 ). Likewise, the shape of the stridulatory files are also not different between the two species ( Fig. 3 ). Hence, these characters are unlikely to be important for species diagnosis.