Cerodontha (Dizygomyza) labradorensis Spencer, 1969

Fig. 9 A – M

Cerodontha (Dizygomyza) labradorensis Spencer, 1969: 120.

Cerodontha (Dizygomyza) poolei Spencer & Steyskal, 1986: 284.

Cerodontha (Dizygomyza) orbitalis Zlobin, 1984 b: 520; 1996: 281.

Specimens examined.

China, Qinghai Province: • 1 ♂ (IMAU), Menyuan County, Zhugu Town, Sigou, 3344 m, 37°06'16.46"N, 102°36'04.03"E, 28. VII. 2021, leg. Li Shi ; • 1 ♂ (IMAU), Qilian County, Lujiaogou, 3417 m, 38°06'31.22"N, 100°28'42.33"E, 01. VIII. 2021, leg. Li Shi .

Diagnosis.

Frons and parafacial projecting above eye. Fronto-orbital plate brownish black, moderately shiny, inner margin yellow, ~ 2 / 3 width of frons; three ori and two ors. Lunule brown with distinctly shining, slightly sunken, broadly semicircular, approx. wider than high. Antennal arista conspicuously thickened on basal 1 / 2. Leg black, only fore femora with yellow knees. Wing with ultimate and penultimate sections of M 4 in proportion of 1.1: 1. Calypter and fringe yellow, margin brownish yellow. Surstylus directed inwards, with 5 thick spines on inner margin; distiphallus S-shaped, ~ 2.5 × length of mesophallus and yellowish brown at apex in lateral view.

Redescription.

Male. Body length 2.3–2.7 mm; wing length 2.4–2.7 mm (Fig. 9 A).

Head (Fig. 9 B, C) dark brown. Frons and parafacial projecting above eye; frons dark brown, ~ 1.4 × as wide as eye; fronto-orbital plate brownish black, moderately shiny, inner margin yellow, ~ 2 / 3 width of frons; three ori and two ors; orbital setulae reclinate or erect in a single row. Ocellar triangle black with yellow margin; ocellar setae conspicuously weaker than ors. Lunule brown with distinctly shining, slightly sunken, broadly semicircular, approx. wider than high. Antennal first flagellomere enlarged with pale pubescence; arista conspicuously thickened on basal 1 / 2. Facial keel distinctly raised. Gena brownish yellow in the center and dark brown on both sides, ~ 2 / 5 height of eye, highest point located at middle of eye. Clypeus light yellow; palpus black, three prominent setae at apex.

Thorax (Fig. 9 D, E) black. Mesonotum and scutellum black, moderately shiny; 1 + 3 dc; acr in four irregular rows; one postsutural intra-alar, one presutural and two strong postsutural supra-alar setae. Anepisternum with one anepisternal seta, eleven short setulae. Katepisternum with one katepisternal seta and four short setulae. Leg black, only fore femora with yellow knees. Wing: Costa with 2 nd (between R 1 and R 2 + 3), 3 rd (between R 2 + 3 and R 4 + 5) and 4 th (between R 4 + 5 and M 1) sections in proportion of 4.1: 1.4: 1; ultimate and penultimate sections of M 1 in proportion of 1.9: 1; r-m slightly beyond middle of discal cell; ultimate and penultimate sections of M 4 in proportion of 1.1: 1. Calypter and fringe yellow, margin brownish yellow. Halter pale yellow.

Abdomen (Fig. 9 F) black, tergites 2–6 with yellow posterior margin. Genitalia (Fig. 9 G – M): epandrium (Fig. 9 H) setose, with a pair of distinctly long claviform processes; surstylus directed inwards, with five thick spines on inner margin; mesophallus swollen at distal 1 / 3 with a medial suture in ventral view; distiphallus S-shaped, ~ 2.5 × length of mesophallus, and yellowish brown at apex in lateral view; ejaculatory apodeme with conspicuously wide stem, blade margin clear; sperm pump pale but base of duct lightly pigmented. Cercus with a long seta in posterior view.

Female. Unknown.

Distribution.

Palaearctic: China (Qinghai) #, Kirgizia, Mongolia (Zlobin 1996), Russia, Tajikistan, Uzbekistan; Nearctic: USA, Canada.

Remarks.

The species is similar to C. (D.) luctuosa in the following characteristics: frons dark brown; arista conspicuously thickened on basal 1 / 2; wing with ultimate section of M 4 equal or slightly longer than penultimate. Legs black, only fore knees yellow; abdomen black and tergites 2–6 with yellow posterior margin; epandrium with a pair of distinctly long claviform processes; distiphallus S-shaped; mesophallus swollen apically. However, it can be distinguished by the following characteristics: the calypter and fringe being yellow, margin brownish yellow; the distiphallus being ~ 2.5 × length of mesophallus, and yellowish brown at apex in lateral view. In C. (D.) luctuosa, the calypter and fringe are whitish yellow; the tubules of the distiphallus have black subapical circle in lateral view (Černý 2010: fig. 45).