Macropelopia excavata Xu & Fu, 2024

Fang, Xiangliang, Xu, Zigang, Yao, Yuanyuan & Fu, Yue, 2024, Two new species of Macropelopia (Diptera, Chironomidae) from Oriental China, delineated with morphology and COI sequences, ZooKeys 1210, pp. 287-298 : 287-298

Macropelopia excavata Xu & Fu sp. nov.

Fig. 1 A – K

Type material.

Holotype male ( HNU: Cdbs 60 ), China: Hubei Province, Huanggang City, Yingshan County, Dabie Mountain , Longtan Gorge , light trap, 31.0867 ° N, 115.8138 ° E, 486.71 m a. s. l., 7. IX. 2022, Zigang Xu .

Etymology.

The new species is named “ excavata ” derived from the Latin term “ excavatus ”, meaning concave, which aptly describes the inward concave shape of tergite IX’s posterior edge.

Diagnostic characters.

The distinguishing characteristics of this new species are the presence of two prominent longitudinal thick spots positioned in the middle of tergites II to IV, and the wing with brown markings on the distal end of Cu 1 and basal part of cell an. Additionally, the tergites from V to IX display a distinctive brown hue, adding to their identification. The posterior edge of tergite IX is concave in shape, and the anal point is absent. The gonostylus is prominently curved at a right angle.

Description.

Adult male (N = 1)

Total length 4.69 mm, thorax length 1.45 mm, wing length 2.66 mm, TL / WL 1.76, WL / Pfe 2.19.

Coloration (Fig. 1 D ). The head and thorax are uniformly dark brown. The femur of the legs is also dark brown, while the remaining parts of the legs are yellow. The wings exhibit two significant gray spots positioned near the Cu 1 and An veins. There is a longitudinal color spot present in the middle of tergites II to IV, the tergites V to IX and hypopygium are all brown in coloration.

Head (Fig. 1 A ). Antenna (Fig. 1 B ) with 13 flagellomeres, with an antennal ratio (AR) measuring 2.24. The flagellomeres taper towards their ends and ultimate flagellomere with a single apical seta. Temporal setae 24, comprising 8 inner verticals, 12 outer verticals, and 16 postorbitals. Tentorial length 234 µm, width 43 µm. Stipes length 192 µm, width 82 µm. Clypeus with 16 setae. Length of palpomeres (in µm): 69; 100; 161; 210; 342. Length ratio of palpomeres 5 / 3: 2.13.

Thorax (Fig. 1 F ). Antepronotals with 9 setae, the acrostichals and dorsocentrals arranged in multiple columns, acrostichals with 41 setae, dorsocentrals with 62 setae. Postnotals with 6 setae, humerals with 8 setae, prealars with 32 setae. Scutal tubercle present and obvious, scutellars with 32 setae.

Wing (Fig. 1 C ). The wing membrane area hairy, distinctive gray spots present near Cu 1 and An veins, the arculus hook-like shape, and the anal lobe mainly developed. VR: 0.91, brachiolum with 3 setae, veins with many setae, squama with 34 setae. Costal extension 128 µm.

Legs. The fore tibia possesses a single spur measuring 85 µm in length and features 15 side teeth. The width of the fore tibia at its apex is 84 µm, and the fore tibial comb consists of 5 setae (Fig. 1 G ). Two spurs of mid tibia are observed, measuring 87 µm and 51 µm long, bearing 16 and 11 lateral teeth, respectively, and has a width at the apex of 73 µm. The hind tibia exhibits two spurs, measuring 75 µm and 45 µm, with 18 and 12 lateral teeth, respectively. The hind tibial comb composed of 10 setae, with the longest seta 73 µm and the shortest 45 µm. The width of the hind tibia at its apex is recorded as 80 µm. The lengths and proportions of each leg are shown in Table 1 .

Hypopygium (Fig. 1 G, H ). The anal point absent. The phallapodeme, although short, measures at a clearly discernible length of 69 µm. The gonocoxite showcases a cylindrical shape and spans 206 µm in length. The gonostylus (Fig. 1 K ) is 125 µm long and exhibits a curved inward shape at approximately two-thirds of its length. It displays protrusions on both the inside and outside, gradually narrowing towards the tip. The megaseta is 16 µm long. The inferior volsella unconspicuous, along the inside of gonocoxite, and contains concentrated long inner microhairs. HR: 1.64, HV: 3.74.

Remarks.

This new species is similar to M. kibunensis (Tokunaga) because their anal point is absent and the inferior volella is undeveloped, but can be distinguished by AR 2.24, wing with brown markings on distal end of Cu 1 and basal part of cell an, otherwise unmarked, and a concave rear edge line of tergite IX, while AR 1.7–1.9, wing with brown markings on distal end of Cu 1, M 3 + 4 and M 1 + 2. The pairwise distance based on the COI sequence of M. kibunensis and M. excavata sp. nov. is 0.105 –0.107, further distinguishing them from each other.

Distribution.

Hubei Province, Oriental China.

Figures

Figure 1. Macropelopia (Macropelopia) excavata Xu & Fu, sp. nov., male imago A head B antenna C wing D whole body of male adult E spotted shape of the tergites F thorax G fore tibial apex H hypopygium, dorsal view I photo of hypopygium, dorsal view J hypopygium, ventral view K gonostylus.