Bioacoustics of Chrysoperla nigrocapitata

Diagnosis . Adults of C. nigrocapitata can be distinguished from all known Old World C. carnea -group species, except C. nipponensis , by the presence of black gradate crossveins. In all other Old World C. carnea -group species the gradates are green. Morphologically adults of C. nigrocapitata cannot consistently be distinguished from C. nipponensis ; however, C. nigrocapitata tends to have darker markings, is larger, and has longer and broader forewings than C. nipponenesis , although there is some overlap in these characteristics. Third-instar C. nigrocapitata larvae can be differentiated from all but the darkest C. nipponensis larvae by the extent of dark pigmentation on their head capsule that yields the prominent white ‘Y’ along the epicranial suture. C. nipponensis larvae usually display the typical pattern for larvae of the carnea- group, with head markings dominated by a prominent pair of brown dorso-lateral stripes set against the pale background color of the body. In cases where C. nigrocapitata larvae display complete dorso-lateral stripes without extensive brown suffusion extending to the eye ( Fig. 3 a), they may be discriminated from dark C. nipponensis larvae ( Fig. 3 h) by presence of a well-developed fronto-medial spot. In summary, only the distinctive phenotypes of the duetting songs can be used to delineate C. nigrocapitata from C. nipponensis absolutely and unequivocally.

Etymology . Named for the nearly solid dark brown or black pigmentation of the dorsal surface of the head capsule of the third-instar larva. Description. Adult . Ground color uniform bright green dorsally, paler green ventrally; pale yellow dorsal stripe running length of thorax and abdomen; body color changes in winter diapause to yellowish- or reddishbrown. Maxillary palp black dorsally on all segments. Stipes marked black, sometimes unmarked basally. Gena with black band. Clypeus laterally with black stripe. Frons unmarked. Pedicel and postocciput unmarked. Pronotal setae mostly pale, occasionally a few black setae present. Metatarsal claw basal dilation ratio 2.02–2.52 (mean ± SD = 2.18 ± 0.16, N =12). Forewing length 11.83–15.33 mm (mean ± SD = 13.71 ± 1.08 mm , N =31), forewing breadth 4.00– 5.33 mm (mean ± SD = 4.77 ± 0.35 mm , N =31), pointed apically; length: breadth ratio 2.76–3.17 (mean ± SD = 2.88 ± 0.11, N =31); basal longitudinal veins and gradate crossveins black, other crossveins entirely black or black at each end, strong black fleck at base of radial vein; costal setae long, inclined towards wing apex. Abdomen bearing partially to mostly blond setae; pleural membrane of second segment unmarked; lip of sternite 8+ 9 in male broad relative to chin (AB> BC) and protruding ( DE > GF). Courtship Song (25ºC) . Song consisting of a single-volley SRU 1.2–2.7 s long (mean = 2.1 s), repeated by solitary individuals several to many times every 3.4–5.0 s (mean = 4.0 s). Each volley subdivided into 4–6 sections exhibiting different dominant frequencies and rapid reversals of frequency modulation; dominant frequency of the most intense middle section is a pure (sinusoidal) tone, rising from about 45 Hz to about 96 Hz during its brief (≈155 ms) duration. SRUs of duetting individuals interleaved temporally and non-overlapping (‘polite’). Third-instar Larva . ( Fig. 1 a, 3a–d) Head: background color cream to pale tan; markings variable. Palest ( Fig. 3 a) with broad, dark brown dorso-lateral stripes, moderately broad baso-lateral expansions, occasionally with poorly defined dorso-lateral spot; lateral brown suffusion not extending to the eyes; sub-medial spots present, usually within pigmented frontal area; fronto-medial spot present; lateral stripes behind eyes dark brown. Darker larvae ( Fig. 3 b, c, d) extensively medium to dark brown, except epicranial suture, antennal bases, and anterior margin of frons; dorso-lateral stripes dark brown anteriad, variable, indistinct ( Fig. 3 b) to dark brown ( Fig. 3 c, d) posteriad; baso-lateral expansions indistinct; dorso-lateral spot absent; sub-medial and fronto-medial spots coalesced in single, triangular pigmented area, often with antero-medial projection; dark lateral stripe behind the eye usually expanded ventrad over gena. Thorax: cream colored to pale tan; pronotum with medium brown, longitudinal, dorso-lateral stripes, 65% with variable red and/or brown suffusion between prothoracic stripes; meso- and metanota with progressively smaller, paler brown spots near mid-length, variably suffused with red and/ or brown; pleura above coxal bases brown; coxal bases dark laterally; femora with broad distal band 0.6–0.75 the length of femur, often darker anteriorly and posteriorly; bases of tibiae pigmented, in darker specimens pigmentation extended over entire tibiae, but paler near mid-length; tarsal apices pigmented. Abdomen: A1–A7 with moderate to extensive red suffusion dorso-laterally; all tubercles white.