Bioacoustics of Cicadetta cantilatrix

Morphology ( Fig. 1 ). The terminology follows Moulds (2005) . Head: slightly broader than mesonotum; black except epicranial suture, base of median postclypeal fissure, and lateral margins of postclypeus, which are yellowish. Anteclypeus black except that its posterior part may be yellowish. Rostrum with labrum and mentum yellowish, labium black. Apex of rostrum reaching bases of mid trochanter. Gena and lorum black with dense and long silvery hairs. Prominent brownish compound eyes, wider than long. Ocellus yellowish or ochraceous, the distance between lateral ocelli shorter than the distance between each lateral ocellus and the nearest eye. Antennae and supra-antennal plate blackish, margins of pedicel yellowish. Thorax: pronotum black, sometimes with an interrupted yellowish median line, lateral angle of pronotal collar and pronotal collar black or brownish. Mesonotum black, scutum black or sometimes with a pair of yellow fasciae in an elongated triangular shape, lateral and submedian sigilla black. Metanotum black, cruciform elevation with posterior and anterior branches black or yellowish, mesonotal scutellar cords black with margin yellowish, wing groove black. Pronotum, mesonotum and metanotum blackish with more or less ochraceous margins. Opercula separated, black with a large yellowish posterior margin. Wings: fore wing hyaline with eight apical cells, sometimes with a ninth aberrant apical cell and with aberrant median and aberrant radial anterior veins. Wing nervation yellowish except apical cells and a part of ulnar cells, which are blackish. Median and cubital anterior vein shortly fused at their bases, veins not aligned. Hind wing with six apical cells, sometimes with a seventh aberrant apical cell and aberrant median veins. Venation blackish to brownish, ambient vein blackish, vannus hyaline with margins blackish, plaga and anterior margin of jugum brownish with blackish spot inside jugum. Legs: yellowish-brownish and black. Fore legs with coxa black, their margins more or less brownish; trochanter black with posterior margin slightly brownish; femur with anterior side black and yellowish spot more or less expanded, posterior side brownish except a blackish spot inside, three spines black, the primary spine strong and oblique, isolated from the two others, the secondary sharp and sub-perpendicular, the apical spine short and triangular; tibia yellowish with the posterior margin black; tarsus yellowish with pretarsal claw blackish. Mid legs with coxa black except the latero-posterior side sometimes brownish, its apical border yellowish; trochanter black with base and ventral margin more or less brownish; femur brownish with blackish longitudinal stripe of variable width; tibia yellowish; tarsus yellowish with claw blackish. Hind legs similar to mid legs or lighter in colour. Abdomen: tergites black with posterior margins orange, auditory capsules sub-circular, convex and black. Tymbal bearing a series of three long ribs, alternating with three very short ribs, the three long ribs connected by a dorsal bar and running dorsoventrally to the tymbal plate. Sternites orange with an antero-median spot more or less wide, that gradually narrows to the apex of the abdomen. Genitalia: pygofer curved with an upper lobe rounded, moderately developed, distant from dorsal beak. Median lobe of uncus curved upwards, clasper hooked. Thecal pseudoparameres filiform and much longer than theca, originating near thecal base. Body measurements: Only two specimens, a male and a female, are available. The first value refers to the male and the second to the female. Measures are in millimetres. Length of body: 17.1 – 21.6. Length of fore wing: 19.9 – 21.6. Width of fore wing: 7.6 – 9.2. Length of head: 1.3 – 1.9. Width of head, eyes included: 5.0 – 5.8. Width of pronotum, supra-humeral plate included: 6.3 – 6.9. Width of mesonotum: 5.5 – 6.0. Acoustic behaviour ( Figs. 2–4 ). A typical calling song sequence consists of two alternating phrases: one phrase of short echemes produced at a slow rate (short echeme duration [ ED ], long inter-echeme duration [ IED ]) and the other of long echemes emitted at a faster rate (long ED , short IED ) ( Fig. 2A,B , Table 1 ). The histogram and density function of ED show a bimodal distribution with negative kurtosis (s4 = -1.29) ( Fig. 3 ). This confirms the production of two distinct categories of echemes with short and long duration respectively. The majority of echemes (99 %) are made of two parts: the echeme starts with a quiet part and finishes with a loud part. First part duration ( FPD ) shows a bimodal distribution similar to that of ED with similar negative kurtosis (s4 = -1.31). ED and FPD are in fact highly correlated (Spearman’s rank correlation: R= 0.999, p <2.2*10-16). ED (s) IED (s) FPD (s) SPD (s) FPF (kHz) SPF (kHz) C. cantilatrix sp. nov. Phrase 1 (n=184) 0.169 ± 0.149 0.972 ± 0.522 0.146 ± 0.143 0.023 ± 0.010 13.478 ± 1.060 13.612 ± 0.939 Phrase 2 (n=406) 0.458 ± 0.185 0.437 ± 0.244 0.427 ± 0.183 0.031 ± 0.008 13.133 ± 0.982 13.575 ± 1.005 All (n=590) 0.368 ± 0.220 0.604 ± 0.433 0.339 ± 0.215 0.028 ± 0.010 13.240 ± 1.018 13.586 ± 0.985 C. cerdaniensis Phrase 1 (n=75) 0.044 ± 0.010 0.844 ± 0.214 0.016 ± 0.007 0.027 ± 0.004 15.442 ± 0.233 15.473 ± 0.223 Phrase 2 (n=85) 0.12 ± 0.043 1.037 ± 0.196 0.085 ± 0.040 0.036 ± 0.004 15.299 ± 0.299 15.541 ± 0.293 Phrase 3 (n=333) 0.038 ± 0.005 0.233 ± 0.088 0.012 ± 0.040 0.026 ± 0.005 15.514 ± 0.419 15.515 ± 0.418 All (n=493) 0.053 ± 0.036 0.464 ± 0.365 0.025 ± 0.032 0.028 ± 0.006 15.470 ± 0.386 15.510 ± 0.375 In the frequency domain, most of the spectral energy is between 11 kHz and 18 kHz. The dominant frequency is not constant but does not show a clear modulation pattern ( Fig. 4 ), and is on average around 13 kHz ( Table 1 ). The dominant frequency of the first echeme part ( FPF ) is slightly but significantly lower than that of the second part ( SPF ) (Wilcoxon test for paired samples, V = 40689.5, p = 3.57*10-16). Habitat ( Fig. 5 ). In Haute-Isle and La Roche-Guyon, C. cantilatrix sp. nov. inhabits closed grassland on Seine River slopes. The two stations consist of axeric vegetation belonging to the sub-xeric class and temperate subclass (SX3) following Defaut’s phytoclimatic classification ( Defaut, 1996 ; 2001 ). In one site, C. cantilatrix sp. nov. shares the habitat with C. brevipennis . Their emergence periods seem to be slightly shifted, C. cantilatrix sp. nov. appearing before C. brevipennis .