Rheocricotopus (Psilocricotopus) kongi Lin et Wang, 2020

Lin, Xiao-Long, Yu, Hai-Jun, Wang, Qian, Bu, Wen-Jun & Wang, Xin-Hua, 2020, DNA barcodes and morphology confirm a new species of Rheocricotopus (Psilocricotopus) orientalis group (Diptera: Chironomidae), Zootaxa 4768 (2), pp. 282-290 : 286-289

Rheocricotopus (Psilocricotopus) kongi Lin et Wang sp. n.

( Figs 4–6 )

urn:lsid:zoobank.org:act:F28D026F-BFD6-4D47-B99A-B2F65881A04E

Type material. Holotype: male ( BDN & BOLD sample ID: XL1857), China, Hainan Province, Baisha County, Yinggeling National Nature Reserve , 19.08333°N, 109.50000°E, 540 m a.s.l., 3.XII.2010, sweep net, F.Q. Kong . Paratype: two males ( BDN & BOLD sample ID: XL1853, XL1856) as holotype.

Etymology. Named after Dr. Fanqing Kong, the collector of type specimens; noun in genitive case.

Diagnostic characters. The male imago can be distinguished from known species of the Rheocricotopus (Psilocricotopus) orientalis group by the following combination of characters: thorax ground colour brown with dark brown stripes on scutum, laterally under parapsidal suture and postnotum; tergite I, IV, VII, 2/3 anterior of VI yellow, remaining tergites, head, antenna, wing and legs brown; AR 0.35–0.37; LR 1 0.82–0.86; squama with one seta; anal tergite without setae; anal point tapering to sharp point, with 4–6 lateral setae on each side; superior volsella thumb shaped and relatively low; inferior volsella broad thumb shaped; costa dorsalis triangularly rounded.

Description. Male (n = 3). Total length 2.20–2.45, 2.32 mm. Wing length 1.35–1.55, 1.43 mm. Total length/ wing length 1.48–1.75, 1.62. Wing length/length of profemur 1.71–1.89, 1.78.

Coloration. Head, antennae and legs brown. Thorax ground colour brown with dark brown stripes on scutum, laterally under parapsidal suture and postnotum. Tergite I, IV, 2/3 anterior of VI and VII yellow, remaining tergites brown ( Fig. 4A ), and gonostylus yellow. Wing pale brown.

Head. Antenna with 13 flagellomeres, ultimate flagellomere 165–185, 175 μm long. AR 0.35–0.37, 0.36. Tem- poral setae 2–3, 2 including 0–1 inner vertical and 1–2, 2 outer verticals. Clypeus with 6–10, 8 setae. Tentorium 130–193, 154 μm long, 25–27, 26 μm wide. Palpomere lengths (in μm): 25–62, 41; 50–63, 54; 103–110, 106; 123–128, 125; 252–258 (n = 2). L: 5 th /3 rd 2.40–2.53 (n = 2). Palp segment five lanceolate sensilla clavate at apex.

Wing ( Fig. 4D ). VR 1.09–1.11, 1.10. Costa extension 85–100, 92 μm long. Brachiolum with one seta. R with 10–11, 11 setae, R 1 with 5–6, 6 setae, R 4+5 with 5–7, 6 setae, remaining veins and cells bare. Squama with one seta. Anal lobe reduced.

Thorax ( Fig. 4 B–C). Humeral pit pale, oval. Antepronotum with two setae. Dorsocentrals 6–9, 8; acrostichals 8–11, 10; prealars 3. Scutellum with three setae.

Legs. Spur on fore tibia 25–28, 26 μm long. Spurs of mid tibia 13 μm and 10–12, 11 μm long; spurs of hind tibia 33 μm and 11–17, 14 μm long. Width at apex of fore tibia 35–38, 36 µm, of mid tibia 38–45, 40 µm, of hind tibia 45–53, 48 µm. Hind tibial comb with 9–16, 13 spines. Lengths (in μm) and proportions of legs as in Table 2.

Hypopygium ( Fig. 5–6 ). Tergite IX without median setae. Anal point tapering to sharp point, with 4–6 lateral setae on each side. Laterosernite IX with 2–4, 3 setae. Proctiger developed. Gonocoxite 150–165, 155 μm long, with caudomedial projection. Superior volsella thumb shaped and relatively low, 13–16, 15 μm long with 12–13, 12 setae. Phallapodeme 50–68, 57 μm long. Transverse sternapodeme 30–35, 32 μm long, without oral projections. Inferior volsella broad thumb shaped, 29–31, 30 μm long. Gonostylus 68–75, 73 μm long, with well-developed tri- angularly rounded costa dorsalis. Megaseta 13–14, 13 μm long. HR 2.00–2.43, 2.14. HV 3.07–3.3.27, 3.19.

Immature and females unknown.

Remarks. The new species resembles R. calviculus in the hypopygium, but can be separated from the latter species by having Tergite VII and 2/3 anterior of VI yellow, a lower AR and broad thumb shaped inferior volsella. The new species also separates from R. calviculus by more than 19.7% divergence in partial COI sequences ( Fig. 3 ). A pale and oval humeral pit presents in R. kongi sp. n., which not fitting the diagnosis of the R. orientalis group ( Wang & Saether 2001).

Figures

FIGURE 3. Neighbor joining tree for four species of the Rheocricotopus (Psilocricotopus) orientalis group based on K2P distance in DNA barcodes. Numbers on branches represent bootstrap support (>70%) based on 1000 replicates; scale equals K2P genetic distance.

FIGURE 4. Rheocricotopus kongi sp. n., adult male. A. abdomen; B. thorax; C. humeral pit; D. wing.

FIGURE 5. Rheocricotopus kongi sp. n., adult male hypopygium of holotype, dorsal view.

FIGURE 6. Rheocricotopus kongi sp. n., adult male hypopygium of holotype, ventral view.