Microchironomus cavus, Yan, Chuncai & Wang, Xinhua, 2006

Yan, Chuncai & Wang, Xinhua, 2006, Microchironomus Kieffer from China (Diptera: Chironomidae), Zootaxa 1108, pp. 53-68 : 54-56

Microchironomus cavus sp. n.

( Fig. 1 A–E)

Material examined: Holotype male, CHINA: Sichuan Province, Xiangcheng County, Shuoquhe River, 2750 m a.s.l., 12.VI.1996, light trap, X. Wang (BDN no. 11908). Paratype male, same data as holotype (BDN no.11907).

Diagnostic characters: The new species is distinguished from other known species by the parallel­sided, slightly swollen superior volsella with two or three pits at the apex, and by the gonostylus with a strong longitudinal keel and no projection on the inner margin.

Etymology: The species name is from Latin, cavus , meaning pit, in reference to the superior volsella, which has two or three pits.

Male imago (n = 2, unless otherwise stated)

Total length 4.00–4.08 mm. Wing length 2.23–2.25 mm. Total length/wing length 1.78–1.83. Wing length/length of profemur 2.35–2.47.

Coloration: Thorax yellowish green, with brown vittae; ventral 1/3 of preepisternum, 1/3 of anepisternum, and anterior 1/2 of postnotum dark brown. Front legs dark brown except 2/3 of femora yellowish brown; mid and hind legs with basal 1/8 of tibia, distal 1/2 of tarsi, and tarsi 2–5 dark brown, remaining parts of mid and hind legs yellowish green ( Fig. 1 A).

Abdomen ( Fig. 1 B) yellowish brown, with posterior 1/8 of tergites II–VI, posterior 1/3 of tergite VII, tergites VIII–IX and hypopygium dark brown.

Head: AR 1.50–1.53. Ultimate flagellomere 600–610 µm long. Frontal tubercles cylindrical, 13–15 µm long, 7–8 µm wide. Temporal setae 20–21, including 4–5 inner verticals, 10 outer verticals, and 6 postorbitals. Clypeus with 9–12 setae. Tentorium 108– 125 µm long, 35–37 µm wide. Palpomere lengths (in µm): 37; 42–45; 150; 152–163; 200– 215. Palp segment 5th/3rd 1.33–1.43.

Thorax: Antepronotals 2–4, acrostichals 6–8, dorsocentrals 7–8, prealars 4. Scutellum with 14 setae.

Wing ( Fig. 1 C): VR 1.11–1.13, R with 16–18 setae, R1 with 12–15 setae, R4+5 with 9– 12 setae. Brachiolum with 2–3 setae. Squama with 14 or 15 setae.

Legs: Front tibia with 3 subapical setae, 113–130, 113–118 and 100–105 µm long; spurs of middle tibia 23 µm and 25 µm long, comb with 32–36 teeth, 10–11 µm long; spurs of hind tibia 24–25 µm and 29–31 µm long, comb with 46–52 teeth, 13 µm long. Sensilla chaetica of mid legs absent. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Fig. 1 D–E): Tergite IX with 20–22 setae at base of anal point. Laterosternite IX with 3 or 4 setae. Anal point constricted in the middle and swollen in distal 1/3, 90–92 µm long, 10 µm wide at base, 15–17 µm wide medially, 7–10 µm wide at apex, with ridge covered with microtrichia in basal 1/2. Lobes of tergite IX bearing 3 setae and microtrichia. Superior volsella slender, parallel sided, 80–82 µm long, slightly swollen apically, with 2 or 3 pits at apex, with 3 subapical long setae and without microtrichia. Anal tergite bands Y shaped. Phallapodeme 106–108 µm long. Transverse sternapodeme 45–47 µm long. Gonocoxite 113–115 µm long, with 7 strong setae along inner margin. Gonostylus 208–215 µm long with apical tooth, inner margin lacking projection, concave medially and with strong longitudinal keel, bearing 18–20 setae in 2 rows along inner margin. HR 0.53–0.55, HV 1.90–1.92.

Distribution. The species was collected with a light trap in Sichuan Province in Oriental China.

Figures

FIGURE 1. Microchironomus cavus sp. n. A, legs; a, front leg; b, mid leg; c, hind leg. B, abdomen. C, wing. D, dorsal view of hypopygium. E, ventral view of hypopygium.

Tables

TABLE 1. Lengths (µm) and proportion of legs of Microchironomus cavus sp. n., male (n = 2).

	fe	ti	ta1	ta2	ta3	ta4	ta5	LR
p1	910–950	670–700	1125–1150	550–550	410–420	320–320	160–170	1.64–1.68
p2	850–870	770–780	450–470	250–250	190–200	120–120	100–100	0.58–0.60
p3	1000–1050	1010–1040	690–720	370–380	300–310	180–180	120–120	0.68–0.69