Bioacoustics of Pterapotrechus salomonoides

Description. — Karny’s (1929) original description of the species (see Suppl. material 1 : appendix A) is for the adult female only. The male was never described. While Karny’s description is minutiously accurate, it is wordy and hard to follow with few illustrations. Curiously, it lacks any mention of the stridulatory apparatus, which in Gryllacrididae is present in both males and females. A new description of the species is given here, based on the examination of 19 fresh specimens, and including a description of the male for the first time. Measurements . See Table 1 . Females tend to be slightly larger than males, but not significantly so. Measurement Males Females Sample size 10 9 Body length (mm) 25.9 (23.8–28.1) 27.6 (21.0–30.7) Pronotum length (mm) 5.3 (4.8–6.8) 6.2 (4.8–6.9) Pronotum width (mm) 6.2 (4.8–7.1) 6.3 (4.9–7.3) Ovipositor length (mm) - 15.4 (13.6–16.8) Ratio ovipositor to body length - 0.59 (0.50–0.70) Length of male cerci (mm) 4.0 (2.6–5.9) - Length of fore femur (mm) 8.1 (7.5–9.2) 8.0 (7.2–9.5) Length of mid femur (mm) 8.4 (7.4–9.2) 8.3 (7.6–9.8) Length of hind femur (mm) 12.9 (11.0–14.5) 13.2 (11.0–15.2) Length of hind tibia (mm) 12.8 (12.3–13.6) 13.3 (10.7–14.4) Ratio hind tibia to body length 0.51 (0.44–0.53) 0.47 (0.43–0.62) Forewing length (mm) 24.2 (20.5–26.7) 21.8 (19.5–26.8) Hindwing length (mm) 25.6 (21.5–27.9) 22.0 (18.9–28.7) Ratio hindwing to forewing length 1.06 (0.96–1.11) 1.07 (0.96–1.09) Stridulatory pegs anterior row T 2 5 (3–6) 4 (3–8) Stridulatory pegs posterior row T 2 8 (6–12) 7 (5–10) Stridulatory pegs anterior row T 3 8 (5–10) 8 (7–10) Stridulatory pegs posterior row T 3 8 (6–10) 9 (8–11) Hind femur ventral spines, inner edge 1 (0–1) 1 (0–1) Hind femur ventral spines, outer edge 2 (2–4) 2 (2–4) Hind tibia dorsal spines, inner edge 3 (2–4) 3 (2–3) Hind tibia dorsal spines, outer edge 2 (2–4) 2 (2–4) Head . (Fig. 6 A, B ). No noticeable sexual dimorphism. Vertex heavily domed, glabrous, smooth, and shiny, pale. Median ocellum visible as a white dot. Just below the ocellum, a shallow V-shaped line separates the pale fastigium from the black frons. The latter is wrinkled throughout and is delimited on the sides by prominent ridges running from the insertions of the antennae to the base of the mandible; these ridges are diagnostic of the genus Pterapotrechus . Mandibles very strong, sharp. Labrum and mandibles dark red / brown. Labial and maxillary palpi pale. Antennae uniform brown, very long, four times the body length or more. Thorax . Pronotum pale; reddish-brown only near the margins. Anterior margin convex in the middle; posterior margin straight. Anterior corners of the lateral lobes in the shape of sharp right angles; posterior corners truncated. A straight median sulcus and two curved sulci on either side of the pronotal discus give the pronotum a characteristic dorsal pattern (Fig. 6 D ). Dark markings on parts of the sulci are often present but not in all individuals. Wings . (Fig. 7 ). Fore- and hindwings well developed in adult males and females. Forewings truncated in apical half, shaped like the blade of a kayak paddle; shorter than body, yet always reaching beyond the end of the abdomen; falling well short of the apex of the ovipositor in females (Fig. 10 B ). Hindwings on average 6 % longer than the forewings. Wing shape as in Chauliogryllacris acaropenates Rentz et al., 2018 and in Béthoux 2012 : Fig. 16. Wing venation simpler than in most other Australian Gryllacrididae ( Béthoux 2012 ) , with veins CuA, CuPaα, and CuPaβ fused into a single vein in both forewing and hindwing. Veins MA and MP share the basal stem with RP in the hindwings. Legs . Fore and mid femora approximately one-third of body length, unarmed. Fore and mid tibiae hairy above; armed ventrally with one pair of spines at the apex (Fig. 6 F ) and with four pairs of strong, sharp spurs that are articulated at the base (Fig. 6 F ; detail in Fig. 6 C ). Hind femora smooth inside, but with a scabrous stridulatory file near the dorsal edge in basal third (Fig. 8 C, D ); armed ventrally in distal half often but not always with one spine on inner edge, always with two to four spines on outer edge. Hind tibiae hairy above, unarmed in basal half (Fig. 6 G ); armed ventrally with one pair of spines near the apex; armed dorsally on both sides with two to four spines in distal half (Fig. 6 G ). Hind tibiae armed with three pairs of apical spurs, one dorsal and two ventral, the ventral spurs being recurved upwards. Abdomen . Shape typical of other Gryllacrididae , with two rows of stridulatory pegs laterally on both tergites T 2 and T 3 (Fig. 8 A, B ). Peg counts in all four rows are reported in Table 1 . Male terminalia . Internal male genitalia soft, non-sclerotized, as in most other Australian Gryllacrididae ( Rentz and John 1990 , Rentz et al. 2018 ). Suranal plate pale, roughly trapezoidal, with two very prominent, darkened, cat’s ear-shaped lobes on the apical vertices (Fig. 9 A ). Subgenital plate triangular, bearing numerous dense, stout spinules on the median keel underneath (Fig. 9 B, C ). Female terminalia . Subgenital plate glabrous, with two pointed lobes giving it the shape of a capital letter M (Fig. 9 E ). Ovipositor on average 60 % of body length, strongly recurved upwards (Fig. 9 F ). Eggs . One female from Kerikeri, New Zealand ( MPN OR 0540) was dissected and found to be carrying 62 eggs in various stages of development. Mature eggs are yellow, elongated, between 4 mm and 4.5 mm long and approx. 1.5 mm wide at center (Fig. 9 G ).