Stenochironomus baishanzuensis Song & Qi, 2022

Song, Chao, Zhu, Bin-Qing, Moubayed-Breil, Joel, Lei, Teng & Qi, Xin, 2022, Taxonomic study on the genus Stenochironomus Kieffer from the Baishanzu Nature Reserve, China (Diptera, Chironomidae), ZooKeys 1104, pp. 93-113 : 93

Stenochironomus baishanzuensis Song & Qi sp. nov.

Figs 6 , 7 , 8

Type material.

Holotype (BOLD & TZU sample ID: ZJCH226; Field ID: BSZ93) 1 male, China, Zhejiang Province, Lishui City, Qingyuan County, Baishanzu National Nature Reserve, 27.76°N, 119.31°E, 11-12. VIII. 2020, Qi X. & Song C., collected by light trap. Paratypes: 2 males, same data as for holotype.

Diagnostic characters.

Adult males of S. baishanzuensis sp. nov. can be distinguished from other related species by the following combination of characters: membrane of wing with large dark spots on median and apical parts; median vitta, lateral vitta, and postnotum with pigmentation; superior volsella short and broad with four setae; inferior volsella with four long bristles and one stout terminal spine, not overreaching apex of anal point.

Etymology.

The specific name refers to the Baishanzu National Nature Reserve, where the holotype was collected.

Description.

Male imago (N = 3). Total length 3.98-4.22, 4.07 mm. Wing length 1.90-2.13, 2.05 mm. Total length / wing length 1.87-2.22, 1.99. Wing length / length of pro-femur 1.63-1.65, 1.64.

Coloration (Fig. 6 ). Head. Antennal hairs dark; palpomeres dark. Thorax almost pale yellow, with posterior portion of media vitta, posterior 3/4 portion of postnotum, and almost the lateral vitta dark brown. Membrane with 2 dark spots located around RM and FCu areas (median spot is darker). Legs. P1: knee, tibia and Ta 1 dark brown, basal 3/4 of femur and Ta 2-5 pale yellowish; P2: yellowish with brownish knee; P3: yellowish with brownish knees and tibia. Abdomen almost light brown with T VI-VII dark brown.

Head. AR 1.93, ultimate flagellomere 810 µm long (n = 1); Temporals 12-15, 13 setae, including 5-7, 6 inner and 4-6, 5 outer verticals and 2-3, 3, postorbitals. Clypeus with 14-20, 18 setae. Tentorium 155-193, 170 μm long, 35-53, 44 μm wide. Palp 5-segmented, lengths (in μm) of segments: 42-55, 47; 43-65, 53; 200-223, 214; 130-155, 146; 232-275, 253. Palpomere ratio (5th / 3rd) 1.13-1.26.

Thorax. Dorsocentrals 15-16, 15; acrostichals 12-15, 14; prealars 6-7, 7. Scutellum with 8-9, 9 setae in 2 rows.

Wing (Fig. 7A ). VR 1.05-1.06, 1.06. Brachiolum with 2 setae. Distribution of setae on veins: R, 30-32, 31; R1, 22-26, 25; R4+5, 36-42, 39. Squama with 10-11, 11 setae. Anal lobe normally developed.

Legs (Fig. 7D ). Fore leg: apex of tibia 55-61, 58 μm width, tibia with pointed scale 35-38 µm long. Mid leg: apex of tibia 60-68, 65 μm width; tibial spurs 48-55, 51 and 45-55, 49 µm long, completely fused at midline part. Hind leg: apex of tibia 60-68, 64 μm width, tibia with 2 apical spurs 37-50, 47 and 35-47, 41 µm long. Lengths (in μm) and proportions of legs in Table 5 .

Hypopygium (Figs 7B, C , 8 ). Anal point 110-125, 120 μm long, 30-45, 35 µm wide at base, 10-13, 12 µm wide at apex. Tergite IX with 18-23, 20 long setae medially, and 3-4, 4 setae laterally. Posterior margin of tergite IX with 3-4, 4 spines and 5-7 long setae each side. Transverse sternapodeme 38-53, 44 μm long; phallapodeme 95-113, 105 μm long. Gonocoxite 183-188, 185 μm long. Gonostylus 218-25, 221 μm long. Superior volsella short and broad, 13-15, 14 μm long, 18-25, 21 μm wide, with 4 long setae (Fig. 7C ). Inferior volsella elongate, 183-192, 187 μm long, extending at most, to apex of anal point, with 4 setae and 1 strong terminal spine. HR 0.83-0.84,.084, HV 1.77-1.93.

Immature stages and female unknown.

Remarks.

The male adult of S. baishanzuensis sp. nov. resembles that of S. gibbus (Fabricius, 1794) in the structure of the hypopygium and the wing patterns, but can be separated by the following characters: straight and parallel-sided anal point, and legs bearing different patterns (Table 4 ).

Distribution.

The species is currently known only from Zhejiang Province, Oriental China.

Figures

Figure 6. Male adult (holotype, in dorsal view) of Stenochironomus baishanzuensis Song & Qi sp. nov. male.

Figure 7. Male adult (holotype) of Stenochironomus baishanzuensis Song & Qi, sp. nov. A wing B hypopygium in dorsal C hypopygium in ventral view D legs.

Figure 8. Male adult (holotype) of Stenochironomus baishanzuensis Song & Qi, sp. nov. A hypopygium in dorsal view B hypopygium in ventral view C superior volsella.