Sirex tianshanicus ( Semenov, 1921 )

3.3.8. Sirex tianshanicus ( Semenov, 1921)

Figure 18 View Figure 18

Paururus tianshanicus Semenov, 1921 , Russkoe Entomologicheskoe obozrenie, 17 [1917]: 91–92. (original description)

Sirex tianshanicus (Semenov) : Xiao and Wu 1983, Memoir of Forest Entomology: 2–5. (original record)

Material examined.

Type specimen: 1 ♀ holotype, Issyk-kul near Przhewalsk , 1918-VIII-05, Ya. Korolkov leg., deposited in Museum St. Petersburg . Additional specimens: 1 ♀, Laomancheng , Urumqi, Xinjiang, 1981-V-24, Fan Yong & Li Hui leg., deposited in Chinese Academy of Forestry . 1 ♂, Kunlun Mountains , Qiemo County, Xinjiang, 1984-VII-12, deposited in Chinese Academy of Forestry .

Diagnosis.

Females with wings largely clear (Fig. 18 A, D View Figure 18 ); vein 3 A of forewings absent; antennae completely blackish; legs largely bright yellowish (except coxae blackish); Males antennae completely darkish; abdomen with segments I – III and IX darkish, IV – VIII yellowish brown; hind femora bright reddish brown.

Female Description.

Color: Head and thorax blackish with dark blue metallic reflections. Antennae and palpi dark brownish to blackish. Legs brownish to yellowish (except coxae black with dark blue metallic reflections). Forewings almost clear. Abdomen blackish with dark purple metallic reflections. — Head: Genae with pits less than 5.4 pit diameters apart; vertex with pits less than 6.6 pit diameters apart, and each pit diameter about 0. 25–0.46 times as lateral ocelli. — Thorax: Mesoscutum with large pits densely developed in median area, more or less reticulate patterns in coarsely pitted area. Metatarsomere 2 with its length 0.84 times length of tarsomeres 3 + 4. Fore wing vein 3 A absent. — Abdomen: Median basin of tergum IX with distinct median longitudinal ridge, basal width about 0.75–0.82 times as long as median length, maximum width 1.0–1.1 times as long as median length, median length 0.7–0.8 times of cornus length. Cornus in dorsal view short, its median length 1.5–1.7 times as long as maximum width of abdomen at junction of terga IX and X. Sheath. Basal section 1.14 times as long as apical section. Ovipositor. Not examined.

Male Description.

Color: Head, thorax and coxae black with dark blue or greenish metallic reflections. Antennae dark brownish to blackish. Fore and middle legs reddish brown from femora to tarsi. Hind legs mostly blackish except femora bright reddish brown. Forewings tinted light yellow and slightly pale brownish near outer margin. Abdomen with segments I – III and IX darkish; segments IV – VIII yellowish brown. — Thorax: Metatibia about 3.1 times as long as maximum width. Metatarsomere 1 in lateral view 3.3 times as long as maximum height.

Distribution.

Xinjiang (near Urumqi, Qiemo County); South Gansu (near Zhuoni County)

Host.

Picea schrenkiana Fisch. & C. A. Mey.

Note.

Our recent field surveys failed to collect this species in Xinjiang, even near its originally reported sites ( Xiao and Wu 1983). This absence could suggest local habitat alterations or undetected ecological requirements. Specimens determined as this species by Xiao are deposited in the collection of the Chinese Academy of Forestry, but their collection date was 1984 (postdating to the original records). This raises questions about their connection to the initial discovery. The ovipositor was not exposed in either of the examined female specimens, preventing examination of this structure.

Females of this taxon show striking morphological similarity to S. dux , with which it has a substantial range overlap. However, the males of the two species exhibit notable morphological differences (e. g. yellowish hind femur in S. tianshanicus while darkish in S. dux ). Detailed comparisons revealed that there are no consistent differences for the standard diagnostic features between the females. A potential distinguishing character is the shape of the median basin on tergum IX (flat-elliptical in Chinese S. dux , cushion-shaped in type specimens of S. dux and S. tianshanicus ), but it appears variable across populations, diminishing its diagnostic value. Notably, multiple morphological measurements (including ratio-based characteristics) showed overlapping ranges between these two species across studies. Currently, leg coloration (bright yellow in S. dux while reddish brown in S. tianshanicus ) serves as the only provisional diagnostic character for the female specimens, as ovipositor comparisons remain unavailable for S. tianshanicus specimens.