Monopelopia zhengi Lin, 2021

Duan, Xin, Chang, Tong, Jiao, Ke-Long, Wang, Xin-Hua & Lin, Xiao-Long, 2021, Monopelopia Fittkau, 1962, a newly recorded genus from Oriental China (Diptera Chironomidae) with a description of Monopelopia zhengi Lin sp. n., Zootaxa 4980 (2), pp. 383-388 : 384-385

Monopelopia zhengi Lin sp. n.

( Figures 1–9 )

Type material. Holotype: male ( NKU: SUN424 ), China, Hainan Province, Ledong City, Jianfengling National Nature Reserve, Tianchi , 18.69273°N, 108.79565°E, 8.iii.2016, light trap, B.-J. Sun . Paratypes: 3 males ( BDN No. SUN422, XL2560, XL2561), as holotype .

Etymology. Named after Prof. Le-Yi Zheng, for his outstanding contribution to the knowledge of insect taxonomy in China.

Diagnostic characters. According to the morphological characters of the adult male, this new Monopelopia species keys to the subgenus Cantopelopia , and is distinguished from other known species of Cantopelopia by the following combination of character states. Antenna with 13 flagellomeres. Fore tibia with single spur, tibia of mid and hind leg each with two spurs. Anal lobe of wing moderately reduced. Phallapodeme sickle-like, slender; sternapodeme with anterior process pointed. Gonostylus simple, wider at the base and tapering gradually to the apex.

Adult male (n = 4). Total length 2.38–2.45 mm. Wing length 1.53–1.60 mm. Total length/wing length 1.53– 1.56. Wing length/length of profemur 2.55–2.65.

Color. Head, palpomeres and antennal flagellum yellow. Thorax: vittae and postnotum brown, scutellum pale, preepisternum with anterior half brown and posterior half yellow. Wings with brownish-yellow membrane, unmarked, covered with macrotrichia. All legs light brown. Abdomen: TI–TVIII with posterior light brown band; hypopygium yellow.

Head ( Figs. 1–2 ). Antenna with 13 flagellomeres; ultimate flagellomere 118–126 µm long; AR 1.10–1.18. Temporal setae 7–8, including 5–6 inner verticals, and 2 outer verticals in continuous row. Eye dorsomedial extension well developed, 97–105 µm long, 40–50 µm wide. Clypeus with 28–32 setae. Tentorium 100–112 µm long; 12–15 µm wide. Lengths of palpomere 1–5 (in µm): 37.5–40, 37.5–42.5, 125–128, 125–130, 227.5–240. Palpomere ratio (5 th /3 rd): 1.82–1.88.

Thorax ( Fig. 3 ). Acrostichals 24–26; antepronotum with 11 lateral setae; dorsocentrals 11; prealars with one seta. Scutellum with 3 setae. Anepisternals, preepisternals and dorsal postnotals absent. Scutal tubercle absent.

Wing ( Fig. 4 ). Membrane covered with microtrichia. Costa without extension. RM near MCu, FCu before MCu. VR 1.15–1.20. Brachiolum with 2 setae. Squama with 6–8 setae. Anal lobe moderately reduced.

Legs ( Figs. 5–7 ). Spur of fore tibia 38–40 µm long; mid leg with two tibial spurs, 50–60 µm long and 20–25 µm long; hind leg with two tibial spurs, 55–62 µm long and 38–45 µm long, and tibial comb distinct, with 6–8 bristles. Lengths (in µm) and proportions of legs as in Table 1 .

Hypopygium ( Figs. 8–9 ). Gonocoxite 180–190 µm long, with a strong basal concavity covered by small setae.

Anal point small and conical, 25–30 µm long. Phallapodeme sickle-like, slender, 140–150 µm long; sternapodeme with anterior process pointed. Inferior volsella absent. Gonostylus simple, wider at the base and tapering gradually to the apex, 140–150μm long, megaseta 20–23 μm long. HR 1.26–1.29; HV 1.63–1.70.

Female and immatures. Unknown.

Discussion: Cranston & Epler (2013) and Silva & Ekrem (2016) treated Cantopelopia as a subgenus of Monopelopia based on larval characters and phylogenetic analyses, and noted the differences between adult males of subgenus Cantopelopia and other Monopelopia species : 1—two tibial spurs on middle and hind legs in subgenus Cantopelopia , a single tibial spur in Monopelopia s. str; 2—an apically wide gonostylus in Cantopelopia , apically attenuate gonostylus in Monopelopia s. str ( Epler 2001). The presence of two tibial spurs on the middle and hind legs and the apically attenuate gonostylus in Monopelopia zhengi Lin sp. n., the former observed in the subgenus Cantopelopia and latter in Monopelopia s. str., challenge the subdivision of Monopelopia into two subgenera, at least as established on adult males. We cannot verify if character states of the immature stages support the separation Further, we also are unable to compare with previously recognised larvae of the genus from south-west Asia. Monopelopia divergens ( Johannsen, 1932) , described in both sexes of adult from Indonesia ( Johannsen 1932) can be distinguished easily by its apically forked vein R 2. The morphology of the new species resembled Monopelopia robacki (Lehmann, 1979) , but is separable by the following character states: antenna with 13 flagellomeres and AR 1.10–1.18 in the new species, whereas antenna of M. robacki has 15 flagellomeres and AR 1.70; gonostylus simple, wider at the base and tapering gradually to the apex in the new species, whereas the gonostylus in M. robacki is apically widened.

Figures

FIGURES 1–4. Monopelopia zhengi Lin sp. n., holotype male. 1. Head; 2. Antenna; 3. Thorax; 4. Wing. Scale bar = 100 µm.

FIGURES 5–9. Monopelopia zhengi Lin sp. n., holotype male. 5. Tibial spur of fore leg; 6. Tibial spurs of mid leg; 7. Tibial spurs of hind leg; 8. Hypopygium; 9. Drawing of hypopygium. Scale bar = 50 µm.

Tables

TABLE 1. Lengths (in µm) and proportions of legs of Monopelopia zhengi Lin sp. n., male holotype (n = 4)

	fe	ti	ta1	ta2 ta3	ta4	ta 5
P 1	600–620	650–700 520–550		280–300 180–210	110–130	80–90
P2	525–550	600–625 500–520		240–260 180–200	100–105	75–80
P3	625–650	750–800 550–600		310–330 180–200	130–150	80–90
	LR		BR	BV	SV
P1	0.78–0.80		2.01–2.23	2.56–2.72	2.35–2.40
P2	0.83–0.84		1.87–2.12	2.63–2.73	2.25–2.26
P3	0.69–0.80		2.34–2.40	2.77–2.82	2.26–2.63