Flagellisargus (Changbingisargus) parvus, Zhang, Junfeng, 2017

Zhang, Junfeng, 2017, New findings of Flagellisargus J Zhang, 2012 (Diptera, Brachycera, Archisargidae), with discussion of the placements of some controversial taxa, Deutsche Entomologische Zeitschrift 64 (2), pp. 111-122 : 111-112

Flagellisargus (Changbingisargus) parvus sp. n. Figs 1, 2, 3D

Diagnosis.

Male archisargid flies 4.9 mm long (excluding antenna); antenna longer than head, scape more than one half of flagellum length; stem of Rs nearly as long as bR4+5; first fork of Rs slightly basad of level of M fork; crossvein r-m linking anterior margin of discal cell near to M fork; crossvein m-m long; section of mM3+4 short; male genitalia large, gonostylus subquadrate with apical denticle medially.

Description.

Small male archisargid flies. Body dark brown but antenna, legs and wings yellowish brown (Fig. 1A). Head moderately large, nearly semiglobose; eyes large, holoptic, occupying anterior part of head (Figs 1A, 2A); antenna very long, clavate, nearly 1.7 times as long as head length, scape elongated, nearly 3.7 times as long as wide; pedicel short, subquadrate, wider than long; flagellum elongate-conical, four times as long as wide, ratio of scape, pedicel and flagellum 1.0:0.3:1.7, arista absent (Figs 1B, 2B).

Thorax subovate, longer and wider than head (Figs 1A, 2A). Wing narrow and long, about 3.1 times as long as wide, C not circumambient, terminating just at wing tip; C, Sc, R1 and Rs clearly stouter than M and its branches; Sc long, more than one half of wing length; R1 straight, nearly third-fourths of wing length; origin of Rs slightly basad to wing midlength, Rs stem short, nearly as long as section bR4+5; first fork of Rs basad to d base; R2+3 straight, ending at C far apart from R1 end; section dR4+5 straight, nearly seven times as long as section bR4+5, 3.8 times as long as R5, R4+5 fork distad to level of R2+3 end, R4 slightly shorter than R5, both veins dR4+5 and R5, more or less, not in line, R5 slightly curved downwards, ending at C clearly before wing tip; ratio of costal sections Sc-R1, R1-R2+3, R2+3-R4 and R4-R5 1.0:0.7:0.4:0.3; ratio of Rs, bR4+5, dR4+5 and R5 1.0:1.0:6.5:1.9; r-m shorter than bR4+5, meeting anterior margin of d close to its base; ratio of bM1+2 and dM1+2 1.0:4.3; M1 slightly arched intermediately; M2 and M3+4 straight, bM2 nearly a quarter of m-m length; ratio of bM3+4, mM3+4 and dM3+4 1.0:0.4:1.9; cell br slightly wider but shorter than cell bm; discal cell hexagonal, about 2.3 times as long as wide; m-cu relatively short, its posterior end distad to M fork; cell cu (traditionally anal cell) narrow, widely open (Figs 1A, 2A). Femur of hindleg moderately long and stout, clavate, nearly reaching posterior margin of fourth abdominal segment, tibia shorter and slightly narrower than femur, tarsus ill-preserved, cylindrical, distinctly thinner than tibia.

Abdomen with seven segments visible, nearly ovate-oblong, fourth widest, and nearly as wide as thorax, 1.8 times longer than head (excluding antenna) and thorax combined; genitalia rather large, subovate, longer but narrower than seventh abdominal segment, gonocoxite more or less oblong with its inner and outer margins slightly curved outwards, gonostylus subquadrate, wider than long, with a triangular apical denticle curved upwards, aedeagus invisible (Figs 1C, 2C).

Dimensions.

Holotype (NIGP DHG 201701): length of body, 4.9 mm; head (excluding antenna), 0.7 mm; thorax, 1.0 mm; abdomen (including genitalia), 3.2 mm. Length of wing, 3.8 mm, width of wing, 1.2 mm.

Distribution.

The "Daohugou Formation" (Daohugou Bed), Callovian-Oxfordian; Daohugou, Wuhua, Ningcheng, Inner Mongolia, China.

Remarks.

It should pointed out that the antennal flagellum (first flagellomere) is ill-preserved near to its base. On first view, it may look like the flagellum has two (or multi) flagellomeres (Figs 1B, 2A), but, the flagellum is, in fact, unsegmented (Figs 1D, 2B).