Syntormon sinicum Qian, Tang, Wang & Yang, 2024, sp. nov.

Syntormon sinicum sp. nov. Figs 1 C, D, 2 A – D Diagnosis. Antennal scape with dorsal hairs; postpedicel 1.2 times longer than wide; arista long, much longer than postpedicel, subapical. Fore coxa yellow; mid and hind coxae black; hind femur brown at tip. Description. Male. Body length 3.1–3.3 mm, wing length 3.6–4.0 mm, based on three specimens. Head. Frons wide, metallic green; face narrowed downwards, with gray pollinosity. Antenna (Fig. 2 A) black; scape with 2 or 3 dorsal hairs; pedicel with 1 short, finger-like projection into postpedicel; postpedicel small, short, 1.2 times longer than wide; arista black, subapical, basal segment 0.15 times as long as apical segment. Proboscis and palpus dark brown, with black hairs, palpus with 1 blackish apical bristle. Thorax. Metallic green with pale gray pollinosity. Hairs and bristles on thorax black. 5 acr bristyles uniserate; 6 dc bristles, long and strong; scutellum with 2 strong bristles and 2 much smaller bristles. Propleuron with yellowish hairs. Legs. Mainly yellow; coxa of LI yellow, coxa of LI and LII black; trochanters of LII and LIII brownish yellow or dark brownish yellow; femur of LIII brown apically; tarsi of LI and LII dark brown from tip of tarsomere I onwards; leg of LIII brown to dark brown onwards entirely. Hairs and bristles on legs mostly black; coxa of LI with yellowish hairs and brown apical bristles, coxa of LII with brown hairs and bristles (1 strong long apical bristle dark brown), coxa of LIII with 1 blackish outer bristle. femora of LII and LIII each with 1 ad preapical bristle. tibia of LI with 1 pd bristle at middle and 2 short apical bristles; tibia of LII with 3 ad bristles, 1 pd bristle, 1 av bristle and 3 apical bristles; tibia of LIII with 3 ad bristles, 5 pd bristlesand 4 apical bristles. Relative lengths of tibia and 5 tarsomeres of legs LI: 1.95: 1.0: 0.5: 0.4: 0.3: 0.25; LII: 2.5: 1.2: 0.6: 0.45: 0.25: 0.2; LIII: 3.4: 0.8: 0.7: 0.5: 0.35: 0.3. Wing nearly hyaline; veins blackish, R 4 + 5 and M slightly convergent apically, CuAx ratio 0.55. Squama yellow with brownish yellow hairs. Halter yellow. Abdomen. Metallic greenish with pale gray pollinosity. Hairs and bristles on abdomen mostly black, tergite 1 with yellow lateral hairs and bristles, hairs and bristles on tergites I – V yellow. Male genitalia (Fig. 2 C): epandrium distinctly longer than wide; surstylus with dorsal lobe wide, lateral side with long bristles, ventral lobe very wide with apical bristles; male cercus blunt at tip. Female. Body length 3.0– 3.1 mm, wing length 3.6–4.4 mm based on 3 specimens. Postpedicel slightly short, as long as wide, face wide. Molecular delimitation. In the NJ phylogenetic tree, S. sinicum sp. nov. is sister to S. bicolorellum Zetterstedt, 1843, forming a clade with S. flexible Becker, 1922 (Fig. 3). The interspecific genetic distance between S. sinicum sp. nov. and other Syntormon species ranged from 5.72 % to 20.47 % (Table 2). These results support the classification of S. sinicum as a separate species (Hebert et al. 2003). Type material. Holotype, male, China: Inner Mongolia, Mount Helan, Xiangchizi, 1900 m, 30. VII. 2013, Xiao Zhang (CAU - SYMSYN 003 A 01). Paratypes, 2 females, same data as holotype (CAU - SYMSYN 003 B 01); 5 males 5 females, Mount Helan, Xiangchizi, 1900 m, 7. VIII. 2021, Liang Wang (CAU - SYMSYN 003 C 01 - SYMSYN 003 C 10); 3 males 3 females (OR 762504), Hohhot, Xiaojinggou, 1400 m, 21. VIII. 2021, Xingyang Qian (IGRCAAS - SYMSYN 2 A 01 - SYMSYN 2 A 06). Habitat. This species was collected in forests (Mount Helan, Xiaojinggou). Distribution. China (Inner Mongolia). Remarks. The new species is somewhat similar to S. luchunense Yang & Saigusa, 2001, but it can be distinguished by postpedicel, which is 1.2 times longer than wide. In S. luchunense Yang & Saigusa, 2001, the postpedicel is 2.5 times longer than wide (Yang et al. 2011). The new species is also somewhat similar to S. brevicornis Frey, 1936, but it has one long bristle on the ventral side of the mid tibia (Fig. 2 D), and its fore tibia is yellow. In S. brevicornis, the mid tibia lacks ventral bristles, and the fore tibia is brown at the base (Frey 1936; Negrobov 1975).