Sirex dux ( Semenov, 1921 ), 2025

3.3.3. Sirex dux ( Semenov, 1921) stat. rev. (New record from China.)

Figure 12 View Figure 12

Paururus dux Semenov, 1921 , Russkoe Entomologicheskoe obozrenie, 17 [1917]: 90–91. (original description)

Sirex dux Semenov : Benson, 1943, Bulletin of Entomological Research, 34: 38. (keyed)

Sirex cyaneus dux Semenov : Benson, 1965, The Annals and Magazine of Natural History, series 13, 8 (87): 141. (treated as subspecies of S. cyaneus )

Material examined.

Type specimens: 1 ♀ holotype, “ Abast ” (in Russian) – Abastumani ( Georgia, ca. 41°45’22’’N / 42°49’41’’E) VIII-17 (year not indicated), deposited in Museum St. Petersburg GoogleMaps . Additional specimens: 8 ♀ 1 ♂ Banfanggou Valley , Urumqi, Xinjiang , 2016-VIII-5, Gao T and Lu ZB leg. ; 7 ♀ Daifuseng Village , Wusu, Xinjiang, 2016-VII-3, Gao T and Lu ZB leg. ; 3 ♀ Wulasitai Village , Wusu, Xinjiang, 2016-VII-27, Gao T and Lu ZB leg. ; 4 ♀ Tiereketi Village , Habahe County, Xinjiang, 2017-VIII-5, 1035 m, Gao T and Lu ZB leg. ; 22 ♀ Haxionggou Valley , Miquan, Xinjiang, 2016-VIII-18, Gao T and Lu ZB leg. ; 11 ♀ Jibuku Village , Qitai County, Xinjiang, 2016-VII-14, Gao T leg. ; 2 ♀ Jiadengyu National Forest Park , Altai, Xinjiang, 2017-VII-27, 1418 m, Gao T and Lu ZB leg.

Diagnosis.

Females with wings largely clear (Fig. 12 A, F View Figure 12 ); vein 3 A of forewings absent; antennae completely blackish; legs largely bright yellowish (except coxae blackish); tarsal pad of metatarsomere 2 about 0.8 times as long as ventral length of tarsomere (Fig. 7 B View Figure 7 ).

Female Description.

Color: Head and thorax blackish with dark blue metallic reflections (Fig. 12 A, E View Figure 12 ). Antennae and palpi dark brownish to blackish (Fig. 3 C View Figure 3 ). Legs yellowish (except coxae black with dark blue metallic reflections). Forewings almost clear. Abdomen blackish with dark purple metallic reflections (Fig. 9 C View Figure 9 ). — Head: Genae with pits 0.3–5.6 pit diameters apart (Fig. 6 C View Figure 6 ); vertex with pits less than 5.0 pit diameters apart, and each pit diameter about 0.12–0.23 times as lateral ocelli (Fig. 5 C View Figure 5 ). — Thorax: Mesoscutum with large pits densely developed in median area, with transverse and longitudinal ridges in coarsely pitted area. Metatarsomere 2 in lateral view about 2.2–2.3 times as long as height, length about 0.9–1.0 times length of tarsomeres 3 + 4; tarsal pad about 0.8 times as long as ventral length of tarsomere (Fig. 7 B View Figure 7 ). Forewings vein 3 A absent. — Abdomen: Median basin of tergum IX with basal width about 0.8–1.0 times as long as median length, maximum width 1.3–1.5 times as long as median length, median length 0.6–0.8 times of cornus length. Cornus in dorsal view short, with edges straight, its median length 0.9–1.1 times as long as maximum width of abdomen at junction of terga IX and X. Sheath. Basal section 1.05–1.15 times as long as apical section. Ovipositor. Pits near middle annuli (the area at base of apical section of sheath) 0.13–0.18 times as long as an annulus (Fig. 10 B View Figure 10 ), pits moderately decreasing in size toward ovipositor base, 0.18–0.30 times as high as lancet height in lateral view, 1.08–1.60 times as long as pit height.

Male Description.

Color: Head, thorax, and coxae black with dark blue metallic reflections (Fig. 12 C, D View Figure 12 ). Antennae and hind legs blackish (Fig. 3 D View Figure 3 ). Fore and middle legs with tarsus yellowish, femora and tibiae dark yellowish brown. Forewings tinted light yellowish. Abdomen segments I – IV, VIII and sternum IX black with dark blue or purple metallic reflections, segments V – VII largely light yellowish with apical part of each segment darkish with purple metallic reflections (Fig. 9 D View Figure 9 ). — Thorax: Metatibia 3.6 times as long as maximum width (Fig. 8 B View Figure 8 ). Metatarsomere 1 in lateral view 2.9 times as long as maximum height.

Distribution.

Gansu (Zhangye City; Wuwei City; Baiyin City), Ningxia (Helan Mountains), Qinghai (Menyuan County), Xinjiang (Urumqi; Shihezi City; Yili City; Tacheng City; Altay Prefecture; Changji Prefecture).

Host.

Picea obovata Ledeb. ; P. schrenkiana Fisch. & C. A. Mey (Fig. 19 View Figure 19 ).

Note.

Females of this species can be easily distinguished from other Chinese Sirex species (excluding S. tianshanicus ) by their entirely black antennae and predominantly yellowish legs. Although initially collected during field surveys conducted several years ago and known to exhibit a broad distribution across western China, no formal records of this taxon were published prior to this study. Notably, this study is also the first formal description of the male of the species, even though only one specimen was obtained through several years’ fieldwork. This taxon historically classified as a subspecies of S. cyaneus , our phylogenetic analysis suggests that S. dux and S. nitidus form a monophyletic group, which is sister to S. cyaneus . Based on the molecular findings and consistent morphological differentiation, we propose reinstating S. dux stat. rev. as a distinct species.