Syntormon sinicum, Qian & Tang & Wang & Yang, 2024

Qian, Xingyang, Tang, Chufei, Wang, Ning & Yang, Ding, 2024, Syntormon Loew (Diptera, Dolichopodidae) from Inner Mongolia, China, with the description of a new species, ZooKeys 1212, pp. 143-152 : 143-152

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).

Figures

Figure 1. Habitus, lateral view A S. dukha Hollis, 1964, male B S. henanense Yang & Saigusa, 2000, male C S. sinicum sp. nov., male D S. sinicum sp. nov., female. Scale bars: 1 mm.

Figure 2. Syntormon sinicum sp. nov., male A antenna, lateral view B hypandrium, lateral view C genitalia, lateral view D mid leg, lateral view. Abbreviations: pha = phallus, sur = surstylus, cer = male cercus. Scale bars: 0.1 mm.

Figure 3. The neighbour-joining (NJ) tree of Syntormon species based on 10 mitochondrial COI sequences.