Bioacoustics of Nemobius interstitialis

N. interstitialis sp. nov. N. sylvestris GLM Diagnosis. A cricket of small size (males 1.05–1.33 cm , females 1.03–1.15 cm ). Body pubescent and covered with long chaetiform hairs. Foreleg tibiae lacking a tympanum on either side in both sexes. Male forewing without a stridulatory vein, but with a strongly developed speculum and chordal cells with central ridges around which are profuse secretory pores. Inner margin of female forewing oblique and curved, overlapping in the proximal half ( Figure 3 ). Male genitalia triangular in shape, with the apical lobe of the epiphallus highly developed. Males n= 23 Females n= 42 Males n= 23 Females n= 22 Males p, F Females p, F Pronotum length (PL) 0.16-0.23 0.21 ± 0.02 0.18-0.24 0.21 ± 0.01 0.13-0.19 0.17 ± 0.01 0.17-0.21 0.20 ± 0.01 0.0000 37.51 0.0048 8.57 Pronotum width (PW) 0.16-0.23 0.21 ± 0.02 0.18-0.29 0.26 ± 0.02 0.22-0.28 0.26 ± 0.02 0.23-0.30 0.27 ± 0.03 0.0370 4.63 0.0005 13.65 Fore wing length (TL) 0.22-0.36 0.30 ± 0.04 0.15-0.23 0.20 ± 0.02 0.32-0.42 0.37 ± 0.02 0.18-0.23 0.20 ± 0.02 0.0000 66.91 0.0000 26.25 Hind femur length (FL) 0.47-0.75 0.63 ± 0.08 0.56-0.75 0.69 ± 0.04 0.49-0.67 0.60 ± 0.05 0.55-0.78 0.63 ± 0.07 0.0047 8.87 0.0523 3.91 Hind tibia length (TL) 0.32-0.50 0.43 ± 0.05 0.33-0.51 0.43 ± 0.04 0.36-0.45 0.40 ± 0.03 0.38-0.49 0.44 ± 0.05 0.0012 11.92 0.0598 3.67 Ovipositor 0.40-0.56 0.47 ± 0.04 0.54-0.68 0.61 ± 0.04 0.0000 90.49 FL/PL 2.68-4.00 3.25 ± 0.23 2.79-3.83 3.27 ± 0.26 3.06-4.69 3.55 ± 0.18 2.71-3.90 3.20 ± 0.33 0.0087 7.57 0.5501 0.36 TL/PL 1.76-2.56 2.19 ± 0.18 0.71-1.06 0.95 ± 0.10 2.05-3.00 2.34 ± 0.12 1.90-2.45 2.21 ± 0.16 0.0162 6.25 0.0000 463.61 Male: Head black-brown to black, clypeus and labrum brown. Eyes slightly prominent. Scape dark brown with transverse brownish antennae. Fastigium smooth, a little wider than the scape, with two yellow dots between the median ocellus and the scape, where two pairs of strong setae are inserted. Another three pairs of longitudinal setae in the vertex, from the medium ocellus backward, and another pair just before the inner margin of the lateral ocellus. Space between the median and lateral ocelli a little less than that between the lateral ocelli. Maxillary palps light in color, except for the last segments which are dark at the apices. Third joint cylindrical, one-and-a-half times longer than the fourth, which is conical and flattened toward the apex. Fifth joint more than twice the length of the fourth, conical. Labial palpi light in color with the last segment dark. Basal joint with an oblique upper margin at the level of the second articulation. Submentum with lateral margins rounded ( Figure 4 ). Mentum trapezoidal. Prementum robust, basal segment of paraglossa not welded to the prementum. Pronotum transverse, brownish, ornamented with dark dots; fore and hind margins almost straight with long setae. Lateral lobes dark with many strong and long setae, lower margin very slightly sinuous. Forewings blackbrown, short and brachypterous. Right forewing with axillary (Ax), anal node (AN), anal (A), ulnar (U), postaxillary (Pa) and discoidal (D) veins weakly marked. In contrast, the vein prolongations that form the distal cells strongly patent ( Figure 5 ). Mirror cells [all of medium (M), external (E), and internal (I) cells] and chordal cells (c. c.) very highly developed with a median ridge on each cell ( Figure 5 ). Concave surfaces surrounding the ridges have many grouped excretory pores; the number of pores per group is variable ( Figure 6 ). Stridulating vein (SV) of the right forewing absent, stridulatory file with teeth absent ventrally ( Figure 7 ). SV absent also from left forewing ( Figs. 8 and 9 ). Hindwings vestigial. Legs thin, light in color with some dark ornamentation, mostly on the outer side of the hindmost tibia and femur. Femora and tibiae of foreleg and median leg with strong dispersed setae. Foreleg tibia without a tympanum on any side ( Figure 10 ); with two strong apical spurs, the inner of which is the longer and thicker. Median leg tibia with three apical spurs, one inner and dorsal and two ventral, all of the same size. Tarsomeres 1 of the foreleg and median legs with two serrulated parallel ventral rows of small black spines. Second tarsomere very short with several ventral rows of spines. Thoracic sternites typical of the genus. Hindleg tibiae armored dorsally with three inner and three outer spurs, all strong and thin, arranged alternately ( Figure 11 ); with three pairs of apical spurs of which those in the middle are shorter and more distal, the proximal pair asymmetric, and the inner pair more developed. Body dark, covered with dense short setae, predominantly in the pleural zone. Sternites a lighter honey in color. Tenth tergite deeply sloped. Subgenital plate triangular with the apex slightly blunted. Cerci light and hairy with three types of setae of which the long and thin, and short and hard types are located all along the cercus; and globose setae appear on the inner side of the basal part of cercus. In general, all of the surface of the cercus bears many short setae or microtrichia ( mt ), among which setae termed filiform ( f ) setae and very thin setae termed tricoid ( t ) setae are interspersed. Both of the latter types of setae are inserted into pores that are bordered. Globose setae termed club-shaped setae ( cs ) are located on the inner side of the first half of the cerci; these are smaller basally and increase in size toward the apex ( Figure 12 ). These cs setae presents an internal border ( ir ). Male genitalia ( Figure 14 ): Short and more triangular in shape than are those of N. sylvestris . Apical lobe of the epiphallus well-developed, broad and dilated, overhanging the margins of the sclerites of the epiphallus. External margin of the dorsal plate of the epiphallus nearly straight and convergent. Basally, the plate slopes at a right angle. Apodemes narrow, almost straight, and increasing progressively in width toward the apex, which is angled at the inner margin. Spermatophore plate well developed. Female: General shape as in male, but with lighter tergites ornamented with dark dots. Forewings very short, reaching the hind margin of the first abdominal tergite. Six longitudinal parallel veins very patent dorsally ( Figure 13 ). Lateral lobes with four weakly curved veins. Inner margin of forewings oblique and curved, overlapping in the proximal half. Ovipositor dark and short and does not extend beyond the middle of the extended hindleg tibia, as is characteristic of the genus. Apices of dorsal valves weakly serrulated. Subgenital plate short with a deep obtuse furrow. Measurements in centimeters (males, females): length of pronotum (0.18–0.25, 0.18–0.24); width of pronotum (0.16–0.23, 0.18–0.26); length of right forewing (0.22–0.36, 0.18–0.24); length of hindleg femur (0.47–0.75, 0.16– 0.23); length of hindleg tibia (0.32–0.50, 0.33–0.51); and ovipositor (0.40–0.54). Instars. Eight instars have been identified in N. interstitialis sp. nov. They can be readily distinguished on biometrical and morphological bases (with reference to wing pads and ovipositor valves); they match stages described by Gabbutt (1959b) in N. sylvestris . The four first instars are separated only by size, principally hindleg femur length (Gabbutt 1959b; Barranco 2012). Sexes cannot be separated before the fifth instar, when the four ovipositor valve processes can be seen, although wing pads are still not developed. At the sixth instar, wing pads remain undeveloped, but a small ovipositor not extending beyond the end of the body can be seen in females. At the seventh instar, wing pads are present in both sexes, these are laterally arranged and separated dorsally in the middle of the second thoracic segment. In this instar the ovipositor extends beyond the end of the body. At the eighth instar the wing pads are bigger, contact each other dorsally in the middle of the thoracic segment, and the ovipositor is twice the length of that in the prior instar. Table 2 shows the proportions of samples in each instar, separated by sex from the fifth instar, obtained throughout the sampling period.