Microchironomus tener (Kieffer)

Yan, Chuncai & Wang, Xinhua, 2006, Microchironomus Kieffer from China (Diptera: Chironomidae), Zootaxa 1108, pp. 53-68 : 61-65

Microchironomus tener (Kieffer)

( Fig. 4 A–G)

Chironomus tener Kieffer 1918: 48

Cladopelma sinuosus Kieffer 1924: 393

Cryptochironomus aegyptius Kieffer 1925: 288

Chironomus (Cryptochironomus) tener Kieffer Goetghebuer 1928: 174

Chironomus (Cryptochironomus) balticus Pagast 1931: 218

Chironomus (Cryptochironomus) primitivus Johannsen 1932: 531 , Sublette et al. 1973: 405, Saether 1977: 101, Wang et al. 1977: 231

Tendipes (Parachironomus) tener Kieffer Krusenman 1933: 125

Chironomus (Cryptochironomus) aegyptius Goetghebuer 1936: 469

Chironomus forcipatus Freeman 1954: 20, 1957: 394 , 1961a: 699

Leptochironomus tener (Kieffer) Kugler 1971: 341 , Shilova 1976: 118 –119, Pinder 1978: 126

Microchironomus tener (Kieffer) Saether 1977: 101 ; Freeman and Cranston 1980: 193; Moller–Pillot 1984: 244; Chaudhuri and Chattopadhyay 1988: 177, 1990: 160; Sasa and Kawai 1987: 61; Kikuchi and Sasa 1990: 300; Sasa 1991: 82; Sasa et al. 1999: 186; Wang et al. 1991: 10; Wang 2000: 645

Cryptochironomus tener (Kieffer) Wang et al. 1977: 230

Parachironomus tener (Kieffer) Hashimoto et al. 1981: 19

Material examined: Tianjin City, Jixian County, Yuqiao Reservoir, 1 male, 2. X. 1986, X. Wang; Hebei Province, Panjiakou Reservoir, 1 male, 25. IX. 2001, sweep net, R. Zhang; Shanxi Province, Taiyuan City, 1 male, 10. VII. 1987, F. Han; Zhejiang Province, Qingyuan County, Baishanzu, Chameixu, 1300 m, 1 male, 18. IV. 1994, H. Wu; Anhui Province, Tongling City, 3 males, 30. VII. 1994, light trap, X. Wang; Fujian Province, Jianning County, 3 males, 26. IX. 2002, light trap, Z. Liu; Jiangxi Province, Poyang Lake, Nanjishan Natural Conversation, 5 males, 12. VI. 2004, sweep net, light trap, C. Yan; Shandong Province, Zaozhuang City, Beizhuang Town, 2 males, 28. V. X. Wang; Hubei Province, Hefeng County, Fenshuiling, 1200 m, 3 males, 16. VII. 1999, B. Ji; Guangdong Province, Fengkai County, Heishiding, 2 males, 19–20. IV. 1988, sweep net, light trap, X. Wang; Hainan Province, Changjiang County, Bawangling Natural Conversation, 7 males, 11. V. 1988, light trap, X. Wang; Hainan Province, Jianfengling Natural Forest Park, 2 males, 15. IV. 1988, X. Wang; Sichuan Province, Xichang City, 1 male, 4. VI. 1996, light trap, X. Wang; Guizhou Province, Libo County, Maolan Town, 500–700 m, 3 males, 3. VIII. 1995, light trap, W. Bu; Guizhou Province, Luodian County, 2 males, 9. VIII. 1995, sweep net, W. Bu; Yunnan Province, Dali City, Zhonghelin, 200m, 2030–2800 m, 43 males, 22. V. 1996, light trap, X. Wang & Y. Du; Yunnan Province, Dali City, Guancangshan, Qingbixi, 2370–2520 m, 12 males, 23. V. 1996, light trap, Y. Du & B. Wang; Yunnan Province, Dali City, Yinqiao, 2000 m, 10 males, 21. V. 1996, X. Wang; Yunnan Province, Dali City, Erhai, 2000 m, 9 males, 23. V. 1996, light trap, X. Wang; Yunnan Province, Jinghong City, 4 males, 3. IV. 1987, H. Zou; Yunnan Province, Lijiang County, Shigu Town, Chongjianghe River, 1850 m, 4 males, 25. V. 1996, B. Wang & C. Zhou; Yunnan Province, Jianfeng County, 3 males, 17. V. 1988, X. Wang; Yunnan Province, Huaping County, Xinzhuang village, Liangmahe River, 2 males, 30. V. 1996, light trap, X. Wang; Yunnan Province, Dali City, Hudiequan, 1 male, 23. 5. 1996, X. Wang; Yunnan Province, Eryuan County, Niujie Town, Futian village, Meicihe river, 2332 m, 1 male, 11. VIII. 1998, light trap, B. Wang; Gansu Province, Linze County, 1 male, 22. VI. 1993, light trap, G. Liu; Ningxia Province, Yinchuan City, 5 males, 26. VII. 1987, X. Wang; Taiwan Province, 7 males, 2000, 2003, K. Ma.

Male imago (n = 26, unless otherwise stated)

Total length 2.10–3.98, 3.08 mm. Wing length 1.00–2.00, 1.41 mm. Total length/wing length 1.95–2.85, 2.12. Wing length/length of profemur 2.30–2.78, 2.58.

Coloration: Eyes slightly brown or black brown. Color of thorax variable, entirely brown or slightly yellowish, with black vittae, ventral 2/3 of preepisternum, most of anepisternum, and anterior 1/2 of postnotum black ( Fig. 4 A); brown with 1/3 of preepisternum and postnotum black or only 1/3 of postnotum black. Femora and distal 1/3 of tibia of front leg yellowish brown, remaining parts of front leg dark brown, mid and hind legs yellowish brown, or tarsi 2–5 or tarsi 4–5 dark brown. Abdomen yellowish green to brown and dark brown in middle ( Fig. 4 B) or entirely brown.

Head: AR 1.33–2.06, 1.72. Ultimate flagellomere 350–650, 501 µm long. Frontal tubercles present or absent, if present, cylindrical, 8–25 µm long, 4–13 µm wide, or rounded 3–8 µm in diameter. Temporal setae 5–15, 8, including 1–6, 2 inner verticals, 1–5, 2 outer verticals, and 2–6, 4 postorbitals. Clypeus with 10–18, 13 (21) setae. Tentorium 100–130, 117 (20) µm long, 15–32, 20 (20) µm wide. Palpomere lengths (in µm): 25–40, 31; 30–50, 38; 63–125, 86; 83–145, 112; 115–185, 147. Palp segment 5th/3rd 1.46–2.22, 1.73.

Thorax: Antepronotals 1–6, 3 (16), acrostichals 3–8, 5 (19), dorsocentrals 5–11, 7 (21), prealars 2–4, 3 (18). Scutellum with 3–9, 5 (20) setae.

Wing ( Fig. 4 C): VR 1.10–1.29, 1.19 (24), R with 0–8, 3 setae, R1 without setae, R4+5 with 2 setae at apex. Brachiolum with 2 setae. Squama with 4–13, 7 (12) setae.

Legs: Front tibia with 2 subapical setae, 60–120, 73 (17) and 55–80, 70 (8) µm long, spurs of middle tibia 12–22, 16 µm and 14–23, 18 µm long, comb with 16–30, 19 teeth, 8– 10, 8 µm long, spurs of hind tibia 14–23, 18 µm and 18–28, 22 µm long, comb with 18–40, 25 teeth, 8–10, 10 µm long. Tarsus 1 of mid leg with sensilla chaetica 2–28, 12 (23). Lengths (in µm) and proportions of legs as in Table 4 .

Hypopygium ( Fig. 4 D–G): Tergite IX with 10–20, 14 setae at base of anal point. Laterosternite IX with 1–4, 3 setae. Anal point ( Fig. 4 F–G) 65–120, 82 (22) µm long, 14– 25, 18 (22) µm wide at base, 4–8, 5 (22) µm wide at apex, slender, widest at base and slightly constricted medially, sometimes with tubercle on ventral side of base, bearing 6– 15 (14) setae and numerous microtrichia. Ninth tergite with pair of low tubercles on posterior margin near base of anal point, with 4–12, 6 (24) setae and covered by microtrichia. Superior volsella 45–75, 56 µm long with 3–4, 3 (25) setae and without microtrichia. Anal tergite bands V or Y shaped. Phallapodeme 75–120, 78 µm long. Transverse sternapodeme 30–62, 47 µm long. Gonocoxite 70–120, 84 µm long, with 3–5, 4 (24) strong setae along inner margin. Gonostylus 125–193, 154 µm long with apical tooth, swollen medially, inner margin concave, bearing 19–31, 22 setae along inner margin. HR 0.47–0.74, 0.59, HV 1.66–2.49, 2.00.

Distribution: The species is widely distributed in the Afrotropical, Australasian, Oriental and Palaearctic Regions and has been recorded from 17 Chinese provinces.

Remarks: Based on material examined from China and a study of the literature, the species is variable for a number of characters, including the frontal tubercles (present or absent); AR (low [1.33] or high [2.03]); tubercle of the anal point (present or absent); and coloration of the thorax, legs, and abdomen (variable). Generally, in chironomid taxonomy, this extent of variation would suggest different species. However, our study suggests that this variation is intraspecific because the structure of the genitalia and most of the other characters is nearly identical.

Sasa (1987) recorded a new species ( M. ishiii ) from Japan, which differs from other species in the genus by having abdominal tergites II to V each with a conspicuous dark brown mark in the center, and the anal tergite with a setigerous tubercle on the ventral side of the base of the anal point ( Sasa 1995). However, based on the Chinese material, these characters also can be found in M. tener . We, therefore, suspect that M. ishiii Sasa 1987 is a synonym of M. tener (Kieffer) , but refrain from formal synonymy until the types can be examined. However, the species is not included in our key.

Figures

FIGURE 4. Microchironomus tener (Kieffer), Chinese specimen. A, thorax. B, abdomen. C, wing. D, dorsal view of hypopygium. E, ventral view of hypopygium. F, anal point without tubercle. G, anal point with tubercle

Tables

TABLE 4. Lengths (µm) and proportion of legs of Microchironomus tener (Kieffer), male (n = 26).

	fe	ti	ta1	ta2	ta3	ta4	ta5	LR
p1	390–720, 551	250–490, 373	470–980, 676	270–530, 379	200–380, 254	130–270, 176	80–140, 105	1.53–2.18, 1.78
p2	370–720, 518	330–690, 474	200–390, 275	100–200, 175	50–150, 92	50–90, 65	50–80, 57	0.45–0.68, 0.58
p3	440–820, 588	430–850, 625	290–590, 408	170–330, 237	150–250, 185	80–150, 105	60–100, 85	0.55–0.70, 0.56