Cryptochironomus protuberans Yan & Wang

Yan, Chuncai, Zhao, Guangjun, Liu, Ting, Guo, Qin, Hou, Ziyuan, Wang, Xinhua & Pan, Baoping, 2016, A new record and two new species of Cryptochironomus Kieffer, 1918 from China (Diptera, Chironomidae), Zootaxa 4208 (5), pp. 485-493 : 490-492

Cryptochironomus protuberans Yan & Wang sp. n.

( Figs. 3 A–E)

Type material. Holotype: 1 ♂ (BDN No. 27124), China, Xinjiang Uygur Autonomous Region, Yining County, Sayram Lake , 27°31′11″N, 106°54′00″E, 30. vii. 2002, sweeping net, H. Q. Tang . 2 Paratypes: 2 ♂♂ (BDN No. 27126, 27140), data as holotype.

Diagnosis. All legs dark brown. Posterior margin of tergite IX with long pointed projection on each side. Anal point slender, and tapered towards the apex. Superior volsella triangular with microtrichia except basal part. Anal tergite bands V-shaped. Gonostylus fused with gonocoxite, widened at apex.

Description. Male imago (n = 3, unless otherwise stated).

Total length 7.55–8.50 mm; wing length 4.00– 4.65 mm; total length / wing length 1.83–1.89; wing length / length of profemur 3.03–3.32.

Coloration. Thorax yellow brown, with dark brown spots. All legs dark brown. Abdominal tergites brown, hypopygium dark brown.

Head. Antenna with 11 flagellomeres. AR: 2.58–2.78. Ultimate flagellomere 820–900 mm. Frontal tubercles ( Fig. 3 A) column, 50 (2) mm high, 30–33 (2) mm wide at basal. Temporal setae 23 (2), including 6 (2) inner verticals; 10 (2) outer verticals; and 7 (1) postorbitals. Clypeus with 18–20 setae. Tentorium 213–255 (2) mm long, 75–82 (2) mm wide. Palpomere lengths (µm): 58, 115; 215; 190; 273 (1); palp segment 5th / 3rd: 1.27 (1).

Thorax. Antepronotum with 4–6 setae, acrostichals 14, dorsocentrals 24–26, prealars 6 (1). Scutellum with 32 setae (1).

Wing ( Fig. 3 C). VR: 1.04–1.12. R with 22–24 setae. R1 with 16–19 setae. R4+5 with 16–21 setae. Brachiolum with 2–3 setae. Squama with 12–15 fringed setae. Anal lobe developed.

Legs. Front tibia with 3 subapical setae, 125–152 mm, 130–148 mm and 140–158 mm long. Mid leg with 2 tibial spurs, 30–35 mm and 35–43 mm long, ta1 with 6 sensilla chaeticae, comb with 34–40 teeth, 10–15 mm long. Hind leg with 2 tibial spurs, 30–36 mm and 45–55 mm long, ta1 with 1 sensilla chaeticae, comb with 52–60 teeth, 12–18 mm long. Lengths (in µm) and proportions of thoracic legs as in Table 2 .

Hypopygium ( Figs. 3 B, D–E). Posterior margin of tergite IX with long pointed projection on each side, bearing 22–28 setae at base of anal point. Laterosternite IX with 6 setae. Anal point 195–220 mm long, slender, tapered towards the apex. Superior volsella triangular, with 6 long setae apically, with microtrichia except basal part. Inferior volsella ( Fig. 3 B, E) small, completely covered by superior volsella, with 5 long setae, without microtrichia. Anal tergite bands V-shaped. Phallapodeme 150–230 mm long. Transverse sternapodeme 140–180 mm long. Gonocoxite 180–265 mm long, bearing 5–7 strong setae along inner margin. Gonostylus 280–310 mm long, with 20–24 short setae along inner margin, fused with gonocoxite, swell at apex. HR: 0.64–0.85; HV: 2.44– 3.04.

Etymology. The specific name is from Latin protubero, meaning ‘swell or bulge out’, and suffixes ‘– ans ’ referring to tergite IX distal with long pointed projection distally on each side.

Remarks. The male of C. protuberans Yan & Wang sp. n. can be separated from other Cryptochironomus species basing on unusual long pointed projection on each side of tergite IX together with gonostylus fused with gonocoxite, swell at the apex.

The new species resembles C. stylifera ( Johannsen, 1908) in the gonostylus fused with gonocoxite, swell at apex together with the shape of superior volsella and inferior volsella. But the new species can be separated from latter species on the basis of following characters: (1) the AR of the new species (2.58–2.78) is much lower than that of C. stylifera (4.35–5.12); (2) the long pointed projection at each side of tergite IX of new species is sufficient to distinguish it from C. stylifera . Moreover, the new species is also close related to C. jokaprimus Sasa & Ogata, 1999 by the similar anal point (slender, tapered towards the apex) and low AR. However, the superior volsella of the new species is triangular, and inferior volsella is small, whereas C. jokaprimus has a bulbous-like superior volsella and a digital inferior volsella. Also, the body size of C. jokaprimus (4.73 mm) is much smaller than that of new species (7.55–8.50 mm), and the gonostylus of C. jokaprimus is without typical distinctly broadened apex.

Female and immature stages unknown.

Figures

FIGURE 3. Cryptochironomus protuberans Yan & Wang sp. n., male. A—frontal tubercles; B—inferior volsella; C—wing; D—hypopygium (dorsal view); E—hypopygium (ventral view).

Tables

TABLE 2. Lengths (in µm) and proportions of adult male legs in C. protuberans Yan & Wang sp. n. (n = 3).

	P1	P2	P3
fe	1320–1400	1420–1510	1500–1700
ti	1300–1380	1370–1480	1400–1850
ta1	1470–1600	690–770	940–1030
ta2	750–770	320–410	330–410
ta3	700–840	280–350	270–320
ta4	570–630	250–310	180–200
ta5	280–310	210–240	100–130
LR	1.13–1.16	0.50–0.52	0.56–0.63