Parachironomus demissum Yan, Wang & Bu, 2012

Liu, Wen-Bin, Wang, Ying, Zhao, Kang-Zhu, Wang, Cheng-Yan, Zhang, Jun-Yu, Yan, Chun-Cai & Lin, Xiao-Long, 2023, New species, a new combination, and DNA barcodes of Parachironomus Lenz, 1921 (Diptera, Chironomidae), ZooKeys 1153, pp. 121-140 : 121

Parachironomus demissum Yan, Wang & Bu, 2012 comb. nov.

Figs 3 , 4 , 5

Paracladopelma demissum Yan, Wang & Bu, 2012: 291.

Material examined.

Holotype. Male (TJNU: 11430), China, Sichuan Province, Yajiang County, Sandaoqiao Town , 30.01532°N, 101.05134°E, 2460 m a.s.l., 9.VI.1996, light trap, leg: X. H. Wang . Paratypes. One male (TJNU: 11730), China, Sichuan Province, Ya'an City , Baoxing County, Xinglong Elementary School , Xihe River , 30.25800°N, 102.50387°E, 1100 m a.s.l., 19.VI.1996, light trap, leg: X. H. Wang. One male (TJNU: 12886), China, Sichuan Province, Kangding County , Wasigou River , 30.04191°N, 102.09454°E, 2000 m a.s.l., 15.VI.1996, light trap, leg: X. H. Wang. One male (TJNU: 13079), China, Sichuan Province, Shimian County , Nanyahe River , 29.11156°N, 102.23265°E, 1040 m a.s.l., 16.VI.1996, light trap, leg: X. H. Wang .

Additional materials.

Two males (SHOU: XL590, XL592), China, Xizang Autonomous Region , Rikaze City , Yadong County, Xiasima Town , 27.48986°N, 88.90572°E, 3032 m a.s.l., 20.VII.2014, light trap, leg: X. L. Lin .

Diagnostic characters.

The species can be distinguished from known species of Parachironomus by the following combination of characters: AR 0.58-0.67, 0.62; tergite IX with shoulder-like posterior margin; anal point triangular base, constricted in the middle, with a ridge mesally; anal tergite bands V-shaped and fused; superior volsella with a bare triangular projection apically; gonostylus slender, parallel-sided, curved medially, gradually tapered to the top.

Description.

Adult males (n = 6, unless otherwise stated). Total length 3.08-3.60, 3.35 mm. Wing length 1.60-1.89, 1.75 mm. Total length/wing length 1.81-2.10, 1.93. Wing length/length of profemur 2.16-2.63, 2.32.

Coloration. Thorax yellowish brown with pale brown spots. Femora and tibiae of front legs yellowish green with distal parts brown, anterior 1/2 of tarsi I yellowish green, remainder of front legs dark brown; femora, tibiae and basal 1/2 of tarsi I of mid and hind legs yellowish green, remaining dark brown. Abdomen yellowish green to dark brown, with tergites I-V yellowish green, tergites VII, VIII, and hypopygium dark brown.

Head (Fig. 3A ). Antenna with 11 flagellomeres, ultimate flagellomere 250-290, 273 (3) μm long. AR 0.58-0.67, 0.62 (3). Frontal tubercles conical, 13-25, 18 (5) μm long, 8-20, 17 (5) μm wide at base. Temporal setae 17-20, 18; including 3-4, 3 inner verticals; 5-8, 8 outer verticals; and 6-9, 8 postorbitals. Clypeus with 12-16, 15 setae. Tentorium 105-132, 118 (5) μm long, 22-28, 24 (5) μm wide. Palpomere lengths (in μm):30-42, 37 (5); 35-45, 39 (5); 95-119, 109 (5); 130-148, 139 (5); 155-220, 190 (5); Pm5/ Pm3 1.48-2.05, 1.76 (5).

Thorax (Fig. 3D ). Antepronotals with 2-3, 2 setae, acrostichals 5-7, 6, dorsocentrals 7-8, 8, prealars 3. Scutellum with 12-14, 13 setae.

Wing (Fig. 5A ). VR 1.18-1.34, 1.26. R with 13-18, 16 setae, R1 with 12-18, 15 setae, R4+5 with 12-22, 16 setae. Brachiolum with 2-3, 2 setae. Squama with 3-5, 4 setae.

Legs. Front tibia with 3 subapical setae, 80-84, 82; 83-97, 91 and 85-112, 101 (5) μm long. Combs of mid tibia 37-41, 39 μm wide with 18-25, 22 μm long spur, and 41-55, 48 μm wide with 20-34, 27 μm long spur; combs of hind tibia 37-41, 39 μm wide with 23-27, 25 μm long spur, 60-66, 63 μm wide with 28-34, 32 μm long spur. Tarsomere 1 of mid and hind legs without sensilla chaetica. Lengths (in μm) and proportions of legs as in Table 3 .

Hypopygium (Figs 4A, D , 5B, C ). Tergite IX with shoulder-like posterior margin, bearing 16-24, 20 setae at base of anal point. Laterosternite IX with 2 or 3, 3 setae. Anal point 55-67, 63 μm long, 12-25, 19 μm wide at base, 10-14, 13 μm wide apically, originating from caudal margin of anal tergite, triangular base, constricted in the middle, with a ridge mesally, moderately widen to distal and apically swollen (Fig. 4D ). Anal tergite bands V-shaped and fused. Phallapodeme 52-70, 61 μm long. Transverse sternapodeme 30-52, 42 μm long. Superior volsella 55-65, 61 μm long, curved medially, expanded in the apical part, apically with a bare triangular projection, bearing two subapical setae, covered with microtrichia on inner margin. Inferior volsella with moderately blunt caudal projection, not reaching beyond anal tergite margin, and covered by microtrichia (Fig. 4G ). Gonocoxite 90-131, 107 μm long, with three setae on inner margin. Gonostylus 140-174, 168 μm long, slender, parallel-sided, curved medially, gradually tapered to the top, bearing 12-24, 20 setae along inner margin and one stronger seta at apex. HR 0.55-0.94, 0.68. HV 1.86-2.50, 2.09.

Distribution.

China (Sichuan and Xizang).

Figures

Figure 3. Head (A-C) and thorax (D-F) of Parachironomus species A P. demissum (Yan, Wang & Bu), comb. nov. B P. wangi Liu & Lin, sp. nov. C P. nankaiensis Liu & Lin, sp. nov. D P. demissum (Yan, Wang & Bu), comb. nov. E P. wangi Liu & Lin, sp. nov. F P. nankaiensis Liu & Lin, sp. nov. Scale bars: 200 μm.

Figure 4. Hypopygium A P. demissum (Yan, Wang & Bu), comb. nov. B P. wangi Liu & Lin, sp. nov. C P. nankaiensis Liu & Lin, sp. nov. Anal point D P. demissum (Yan, Wang & Bu), comb. nov. E P. wangi Liu & Lin, sp. nov. F P. nankaiensis Liu & Lin, sp. nov. Superior volsella G P. demissum (Yan, Wang & Bu), comb. Nov. H P. wangi Liu & Lin, sp. nov. I P. nankaiensis Liu & Lin, sp. nov. Scale bars: 50 μm.

Figure 5. Parachironomus demissum (Yan, Wang & Bu), comb. nov. holotype male A wing B hypopygium, dorsal view C hypopygium, ventral view.