Sirex nitobei Matsumura, 1912

3.3.5. Sirex nitobei Matsumura, 1912

Figure 15 View Figure 15

Sirex nitobei Matsumura, 1912 , Thousand insects of Japan. Supplement IV: 17–18. (original description)

Sirex nitobei Matsumura : Xiao et al., 1992, Economic Sawfly Fauna of China: 38–42. (described, keyed)

Sirex nitobei Matsumura : Xiao & Wu, 1983, Memoir of Forest Entomology: 2–5. (described, keyed)

Sirex rufiabdominis Xiao & Wu, 1983 , Memoir of Forest Entomology: 2–5. syn. nov.

Sirex sinicus Maa, 1949 , Notes d’Entomologie Chinoise, 13 (2): 124–126. syn. nov.

Sirex imperialis W. F. Kirby : Xiao & Wu, 1983, Memoir of Forest Entomology: 2–5. (original record) [misidentification]

Material examined.

Type specimens: 1 ♀ holotype of Sirex rufiabdominis Xiao & Wu, 1983 , Fuyang District , Hangzhou, Zhejiang, 1986-X-7, deposited in Chinese Academy of Forestry ; 1 ♂ paratype of Sirex rufiabdominis Xiao & Wu, 1983 , “ Yangxian ” probably Chuzhou City (due to illegible handwriting, the exact characters cannot be identified), Anhui, 1981 (month and date not indicated), deposited in Chinese Academy of Forestry . Additional specimens: 1 ♂ Mt. Jiulong , Mentougou District, Beijing, 2015-XII-25 (emerged), Gao T leg. ; 2 ♀ 7 ♂ Chifeng City , Inner Mongolia, Gao T leg. ; 10 ♀ 13 ♂ Fei County, Linyi , Shandong, 2019-IX, Xu Q leg.

Diagnosis.

Females with apical half of forewings moderately to strongly darkened (Fig. 15 A – D View Figure 15 ); vein 3 A of forewings absent; antennae completely blackish (Fig. 3 I View Figure 3 ); tarsal pad of metatarsomere 2 0.7–0.8 times as long as ventral length of tarsomere (Fig. 7 E View Figure 7 ). Males with flagellar basally brownish to dark brownish (Fig. 3 J View Figure 3 ); abdomen segments completely darkish or I – II blackish, III – IX yellowish (Fig. 9 L, M View Figure 9 ).

Female Description.

Color: With different color forms. Head, Antennae and thorax blackish with dark blue metallic reflections. In dark forms, legs blackish with more or less dark blue metallic reflections (Fig. 15 A View Figure 15 ). In red forms, color of legs variable, coxae and femora blackish with dark blue or purple metallic reflections, while tibiae and tarsi from dark brownish to completely light reddish brown (variable based on individuals) (Fig. 15 B, C, H View Figure 15 ). Forewings with basal half clear and apical half brownish to dark brownish (in red form comparatively light but darkened in dark forms), brownish area moderately deepening before pterostigma, sometimes forms vague brownish bands. Dark forms with abdomen completely blackish, terga I and IX always dark blueish metallic reflections while terga II – VIII dark purple metallic reflections in dorsal view (Fig. 9 I View Figure 9 ). Red forms with color of abdomen variable, terga I and IX always dark blueish metallic reflections while terga II – VIII from more or less reddish brown to completely light reddish brown (Fig. 9 J, K View Figure 9 ). — Head: Genae with pits 0.1–2.5 pit diameters apart (Fig. 6 I View Figure 6 ), vertex and postocellar area with pits less than 2.0 pit diameters apart, and each pit diameter about 0.1–0.25 times as lateral ocelli (Fig. 5 I View Figure 5 ). — Thorax: Mesoscutum widely covered with net-like pits in median area. Metatarsomere 2 in lateral view 1.7–2.0 times as long as height, length about 0.9–1.1 times length of tarsomeres 3 + 4; tarsal pad 0.7–0.8 times as long as ventral length of tarsomere (Fig. 7 E View Figure 7 ). Forewings vein 3 A absent. — Abdomen: Median basin of tergum IX with basal width about 0.8–1.1 times as long as median length (always less than 1.0 times in red forms, while more than 1.0 times in intermediate and dark forms), maximum width 0.9–1.3 times as long as median length (always less than 1.0 times in red forms, while about 1.2 times in intermediate and dark forms), median length 0.8–1.1 times of cornus length. Cornus in dorsal view rather short, with edges in the basal half straight and curved apically, distinctly angulate midway, its median length 0.7–0.9 times as long as maximum width of abdomen at junction of terga IX and X. Sheath. Basal section 1.1–1.3 times as long as apical section. Ovipositor. Pits near middle annuli (the area at base of apical section of sheath) 0.27–0.33 times as long as an annulus, pits not decreasing in size toward ovipositor base (Fig. 10 E View Figure 10 ), about 0.4 times as high as lancet height in lateral view, 0.7–0.9 times as long as pits height.

Male Description.

Color: With different color forms. Head, thorax and coxae blackish with dark blue metallic reflections. Antennae with basal half dark brownish to brownish (except for scape blackish) and apical half blackish (Fig. 3 J View Figure 3 ). Fore and middle legs brownish to yellowish brown (except coxae black). Hind legs with femora yellowish brown (in dark forms dark brownish) (Fig. 15 E – G View Figure 15 ); metatibiae blackish. In dark forms with metatarsomere 1–3 and 5 blackish while metatarsomere 4 brownish in dorsal view; in red forms with metatarsomere 1–3 blackish while metatarsomere 4 + 5 yellowish brown. Fore and hindwings yellowish. Abdomen with segments I – II blackish with dark blue or purple metallic reflections; in dark forms with terga III – VIII (including sternum IX) dark brownish (Fig. 9 L View Figure 9 ), while light yellowish brown in red forms (Fig. 9 M View Figure 9 ). — Thorax: Metatibia 4.2–4.9 times as long as maximum width (Fig. 8 E View Figure 8 ). Metatarsomere 1 in lateral view 2.7–3.1 times as long as maximum height.

Distribution.

Almost nationwide: Heilongjiang; Jilin; Liaoning; Inner Mongolia; Beijing; Hebei; Henan; Shandong; Shaanxi; Anhui; Jiangsu; Zhejiang; Gansu; Yunnan; Xinjiang.

Host.

Pinus sp. (e. g. P. tabuliformis Carr. ; P. sylvestris var. mongholica Litv. ; P. thunbergii Parl. ; P. massoniana Lamb. )

Note.

This species is the most widespread Sirex species in China. Earlier studies mistakenly classified different color variants of it as distinct species (i. e. S. rufiabdominis Xiao & Wu ) because their appearance varies greatly. After studying series of specimens (including type series of S. rufiabdominis Xiao & Wu ), we discovered that these color variants are merely individually and continuously with no structural differences. Molecular phylogenetic analysis also confirms that they belong to the same species. Therefore, based on both morphological characters and molecular data, we propose S. rufiabdominis Xiao & Wu as a junior synonym of S. nitobei Matsumura , i. e. S. rufiabdominis Xiao & Wu, 1983 syn. nov. Another confusing case is S. sinicus Maa , which was named based on single male holotype from Beijing, where S. nitobei also occurs. By comparing the original description ( Maa, 1949) with our examined specimens (the type specimen of S. sinicus has not been examined), we found no significant differences between S. sinicus and S. nitobei . We propose S. sinicus Maa as a junior synonym of S. nitobei Matsumura , i. e. S. sinicus Maa, 1949 syn. nov. Additionally, Xiao and Wu (1983) reported S. imperialis W. F. Kirby, 1882 in China based on specimens deposited in the Chinese Academy of Forestry. Our rechecking of these specimens also identifies them as S. nitobei , confirming that S. imperialis does not occur in China.