Decticus albifrons ( Fabricius, 1775 )

Liu, Fei, Chen, Liusheng & Liu, Chunxiang, 2020, Taxonomic Studies of the genus Decticus Serville, 1831 from China (Orthoptera Tettigoniidae: Tettigoniinae), based on Morphology and Songs, Zootaxa 4860 (4), pp. 563-576 : 571-572

Decticus albifrons ( Fabricius, 1775)

Locusta albifrons Fabricius, 1775 . Supplementum Entomologiae Systematicae 2: 86.

Conocephalus albifrons: Thunberg, 1815 . Mem. Acad. Imp. Sci. St. Peterburg 5:273.

Decticus albifrons: Fieber, 1854 . Lotos 4:220.

Decticus aeolicus Guarino, 1935 . Annu. Mus. zool. Univ. Napoli N.S. 6(16):3(syn.).

Material examined. See Table 1 and Table 2.

Diagnosis. Tegmen exceeding knee of hind femora, with narrow and rounded apices ( Fig. 5e ). Male cercus conical, with a black inner tooth at base. Male subgenital plate with distinct lateral carina; cylindrical stylus slightly shorter than cercus, with sharp and black apex ( Fig. 4j & o ). Female tegmen reaching or exceeding ovipositor apex. Female subgenital plate thick, with an acute-angled trianglar incision.

Redescription. Lateral lobe of pronotum about 1.5 times higher than wide; anterior margin inclining backward, posterior margin vertical, and ventral margin circular. Mirror irregular ellipse ( Fig. 6i ). Stridulatory file with about 72–75 widely regularly-arranged pegs; pegs gradually becoming smaller towards both ends ( Fig. 6j ). Male ninth abdominal tergum slightly extending backward with an obtuse angle. Male tenth abdominal tergum with an oval central concavity on dorsal surface; apex shrinking with a shuttle-shaped incision. Male epiproct covered by tenth abdominal tergum, bent down at an angle of 90° ( Fig. 4f ). Male subgenital plate with distinct lateral carinae.

Generally brown, scattered with black and white spots. Face light purple, darkening to both sides. Clypeus pale yellow. Areas around eyes and antennal socket yellow. Occiput brown. Pronotum dark brown; center of pronotal lateral lobes dark brown, becoming black and yellow outwards. Tegmen creamy-brown, scattered with creamy-yellow and black spots. Hind femur black marbled on posterior surface, and brown on ventro-anterior surface. Yellow with the ventral of body.

Song. The calling song consisted of stereotyped chirps with a regular period (147.47±6.75 ms) and duration (104.69±4.46 ms) ( Fig. 7 a–c). Each chirp was comprised of 2 syllable groups. Frequency ranges from 0 to 24 kHz, frequency of main peak is about 8.79 kHz, and that of second peak is not significant ( Fig. 7 d–e). The important parameters are listed ( Tab. 3 ).

Measurements (mm). See Table 6 and Table 7 .

Distribution. The distribution area includes the Canary Islands and Madeira and across the Mediterranean area (North Africa and Europe) up to southwesterm Asia ( Willemse et al. 2018).

Figures

FIGURE 4a–o. Male pronotum and abdominal apex (scale: 1.00 mm). a–e: Pronotum; f–j: The dorsal view of abdominal apex; k–o: The ventral view of abdominal apex.

FIGURE 5a–e. Right tegmen of males. a: D. v. verrucivorus; b: D. v. latipennis ssp. n; c: D. v. sayram ssp. n. d: D. v. crassus; e: D. albifrons.

FIGURE 6a–j. Stridulatory apparatus of Decticus. a, c, e, g, i: Mirror on right tegmen; b, d, f, h, j: Stridulatory file on underside of male left tegmen; a–b: D. v. verrucivorus; c–d: D. v. latipennis ssp. n.; e–f: D. v. sayram ssp. n.; g–h: D. v. crassus; i–j: D. albifrons.

FIGURE 7a–j. Song diagrams per populations. a–e: D. albifrons; f–j: D. v. verrucivorus; k–o: D. v. crassus (The temperature of m2 is 29.8 °C and others are 27 °C.); a–b, f–g, k–l: A phrase series; c, h, m1–2: Elements in a chirp; d, i, n: Sonogram of the calling song; e, j, o: Power spectrum of the calling song.