Synorthocladius semivirens ( Kieffer 1909 )

Liu, Yuedan & Wang, Xinhua, 2005, Synorthocladius Thienemann from China, with a review of the genus (Diptera: Chironomidae: Orthocladiinae), Zootaxa 1057, pp. 51-60 : 55-57

Synorthocladius semivirens ( Kieffer 1909) ( Figs. 5–8 )

Dactylocladius semivirens Kieffer 1909: 48

Dactylocladius breviradius Kieffer 1911: 183

Dactylocladius flaviforceps Kieffer 1911: 183

Spaniotoma tripilatus Edwards, 1929: 348

Orthocladius semivirens ( Kieffer 1909) , Wang & Zhang 1987: 120

Synorthocladius semivirens (Kieffer) , Thienemann 1935: 211. comb. n.; Saether et. al. 2000: 177; Wang 2000: 640.

Material examined: 1 male, CHINA: Shaanxi Province, Zhouzhi County, Banfangzi (33° 49 N, 108° 0 0 E), alt. 1450 m, 9.VIII.1994, light trap, W. Bu, slide no. 03895; 1 male, Shaanxi Province, Fengxian County (33° 54 N, 106° 31 E), alt. 1400 m, 29.VII.1994, light trap, W. Bu, slide no. 08304; 1 male, Shaanxi Province, Ningshaan County, Huoditang (33° 26 N, 108° 27 E), alt. 1640 m, 12.VIII.1994, light trap, W. Bu, slide no. 0 9216.

Male imagines (n = 3 Chinese specimens, except when otherwise stated).

Total length 1.68–2.08, 1.90 mm. Wing length 1.06–1.27, 1.14 mm. Total length/wing length 1.53–1.82, 1.66. Wing length/length of profemur 2.15–3.56, 2.62.

Coloration [slide mounted material]: Head yellow­brown. Thorax yellow with brown vittae, scutum, anterior anepisternum II, preepisternum, and postnotum. Abdominal segments brown with pale posterior margins. Legs yellow. Wings transparent, yellowish.

Head: Terminal flagellomere 180–250, 223 µm long. AR 0.47–0.63, 0.55. Temporal setae 5–7, 6, including 1 inner vertical and 4–6, 5 postorbitals, without outer vertical. Clypeus with 3 or 4, 3 setae. Tentorium ( Fig. 5 ) 103–117, 108 µm long, narrow part straight and with small tubercle. Stipes 113­126, 118 µm long. Palpomere lengths (in µm): 25–36, 31; 28–45, 33; 43–70, 54; 53–78, 62; 83–128, 106.

Thorax ( Fig. 6 ): Antepronotum with 1 or 2, 1 lateral setae. Acrostichals 1, dorsocentrals 3 or 4, 4, prealars 3. Scutellum with 3 or 4, 4 setae.

Wing ( Fig. 7 ): Anal lobe almost right­angled. VR 1.12–1.21, 1.17. R2+3 ends at half distance between R1 and R4+5. Costal extension 35–53, 45 µm long. Brachiolum without setae; R with 1–3, 2 setae; remaining veins bare. Cu1 slightly curved and end of Cu1 slightly recurved. Squama with 6–8, 7 (2) setae.

Legs ( Table 2 ): Spur of front tibia 28–33, 31 µm long, spurs of middle tibia 15–20, 18 µm and 15­20, 18 µm long, of hind tibia 33–55, 42 µm and 15­18, 17 µm long. Hind tibial comb with 8 setae. Middle and hind tibial spurs with developed denticles. Pseudospurs absent.

Hypopygium ( Fig. 8 ): Tergite IX concave inwards and with 13–15, 12 setae. Anal point 12–15, 14 µm long, 2–4, 3 µm wide at base, pointed apically. Anal point length/ width 4.00–6.50, 5.25, with 7–9, 8 setae at base. Phallapodeme 67–87, 73 µm long; transverse sternapodeme 78–98, 88 µm long, oral projection well developed. Gonocoxite 118–165, 139 µm long. Gonostylus slightly arched, 50–84, 65 µm long. Inferior volsella narrow, bent and apically triangular. Megaseta 9–12, 11 long. HR 1.82–2.70, 2.21, HV 2.47–3.86, 3.03.

Distribution: The species is widespread in Europe, Asia, and North America. The Chinese specimens were collected with a light trap in a temperate mountain area in a Palaearctic Chinese Province.

Remark s: Synorthocladius semivirens can be differentiated from the other known species of the genus by having a narrow and apically triangular inferior volsella. When we reviewed the literature regarding this species, we found that all previous descriptions and figures were too simple to allow recognition. We, therefore, have redescribed and illustrated the species based on Chinese specimens.

Figures

FIGURES 5 – 8. Synorthocladius semivirens (Kieffer) (Chinese specimen). 5, tentorium; 6, thorax; 7, wing; 8, hypopygium.

Tables

TABLE 2 Lengths (in µm) and proportion of leg segments of S. semivirens.

	fe	ti	ta1	ta2
p1	430–590, 503	400–560, 473	240–320, 280	210–280, 240
p2	410–530, 467	360–470, 403	180–220, 200	110–140, 123
p3	430–520, 477	420–540, 473	230–270, 250	140–170, 153