Orientisargus illecebrosus, Zhang, 2012

Zhang, Junfeng, 2012, Orientisargidae fam. n., a new Jurassic family of Archisargoidea (Diptera, Brachycera), with review of Archisargidae from China, ZooKeys 238, pp. 57-76 : 59

Orientisargus illecebrosus sp. n. Figures 1 -3

Derivation of name.

Latin, illecebrosus, enchanting, alluding to the special wing venation.

Holotype: NIGP DHG901a, NIGP DHG901b, part and counterpart, a pair of nearly complete female archisargoid flies, is held in the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.

Type area and horizon.

"Daohugou Formation", in the vicinity of Daohugou, Ningcheng, Inner Mongolia, China (uppermost Middle Jurassic - lowermost Upper Jurassic).

Repository.

The Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences.

Description.

Female insect relatively slender and long. Head and thorax dark brown, otherwise yellowish brown. Head large, semiglobose. Antenna stout, scape ovate, pedicel trapeziform, apically wider than basally, flagellomere short and stout with rounded tip, slightly wider than long. Thorax subovate, clearly longer and wider than head. Wing 3.8 times longer than wide, all veins are markedly thickened except M and CuP, which become moderately thin. Sc nearly four-fifths wing length. R1 straight, more than four-fifths wing length. Origin of Rs slightly basal to midpoint of wing or M fork. Rs stem slightly longer than r-m, and less than one-tenth R2+3 length. Basal section of R2+3 straight, distal section clearly arched forward, ending near to wing tip. Rs fork a little distad to M fork. Section bR4+5 very short, dR4+5 arched, and nearly as long as R2+3. Crossvein r-m dividing anterior margin of discoidal cell as 1:21. Discoidal cell about one-third wing length, and 11 times longer than wide. M1 slightly arched forward, and more than one half diacoidal cell length. M2 straight. Section bM2 some as long as m-m. Section bM3+4 as long as bM1+2, and about one half dM3+4 length. Cell m3 rather narrow and long, some 10 times longer than wide. Section dM3 short, about one half m-m length, and nearly perpendicular to M4. Petiole of cell m3 straight, some one-third cell m3 length. Halter relatively short and stout, club subovate, some one-third halter length. Abdomen cylindrical, more than three times longer than head and thorax combined. Hind leg stout and long. Femur clavate, a little shorter, but stouter, than tibia. Tibial spurs slender and long, nearly one-third basitarsus length. Ratio of tarsomeres 1:0.43:0.28:0.11:0.17, basitarsus nearly as long as remainder tarsomeres combined. Claws small, slender. Female cerci small, longer than ninth tergite.

Dimensions.

Length of body 12.2 mm; head, 1.0 mm; thorax, 2.0 mm; abdomen, 9.2 mm. Length of wing, 8.4 mm; width of wing, 2.2 mm. Length of femur of hind leg, c. 4.0 mm; tibia, 4.4 mm; tarsus, 3.2 mm.

Figures

Figure 1. Orientisargus illecebrosus gen et sp. n., NIGP DHG 901 a, NIGP DHG 901 b, part and counterpart, holotype, photographs, female, dorsal view. A B body C antenna D left wing E right wing F part enlarged of left wing G part enlarged of right wing H tarsus of hind leg I abdominal apex of female. Scale bars represent 1 mm except for C and I for which scale bars represent 0.1 mm.

Figure 3. Orientisargus illecebrosus gen et sp. n., line drawings, A antenna of holotype NIGP DHG 901 b B left wing of holotype NIGP DHG 901 a (vein sections bM 1 + 2, bM 3 + 4 and dM 3 + 4 reconverted based on right wing) C halter of holotype of NIGP DHG 901 a D tarsus of hind leg of holotype NIGP DHG 901 b E female cerci of holotype NIGP DHG 901 a. Scale bars represent 1 mm.