Orientisargidae, 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 : 58

Family Orientisargidae fam. n.

Type genus.

Orientisargus gen. n.

Included genus.

The type genus only.

Diagnosis.

Large sized (more than 12 mm) flies. Legs and abdomen slender, strongly pubescent but devoid of bristles; antennal pedicel longest, first flagellomere neither segmented nor arista or style on its tip; wing narrow and long, subpetiolate, alula absent; venation not costalized; R pectinate; C running around entire wing margin although thinned beyond wing tip; C, Sc, R and CuA strong; Sc, R1 and R2+3 long; R4+5 simple (not bifurcated); origin of Rs proximal, nearly at level of M fork; discoidal cell slightly shifted distally; crossvein m-cu absent; M3+4 stem strongly flexed, and touching CuA; cell m3 closed; hind legs stout and long, tibial spurs well developed, empodium wanting; female cerci foliaceous.

Remarks.

This new family demonstrates similar body structures and wing venation to the family Archisargidae Rohdendorf, 1962 based on the following characters: large sized flies with hind legs and abdomen stout and long, body strongly pubescent but devoid of bristles; wing narrow and long, subpetiolate, alula absent; venation: C running around wing margin although thinned beyond wing tip; long and strong Sc and R1 (R1 more than four-fifths of wing length, and clearly stouter than M); and the position of r-m, which meets R4+5 and fore margin of d, respectively; as well as the position of disciodal cell, which is more or less shifted distally. However, from all known representatives of Archisargidae it differs by the simple R4+5, which is not bifurcated, the origin of Rs which is clearly proximal, the strongly flexed M3+4 stem, of which bM3+4 section becomes short, crossvein-like, and touches CuA instead of m-cu; Furthermore, considering the characteristic features that R4+5 is simple, R furcated pectinately and the origin of Rs is proximal, Orientisargidae fam. n. is similar to the family Kovalevisargidae Mostovski, 1997, the sister group of Archisargidae within Archisargoidea . It is distinct from all the kovalevisargids in having longer Sc, R1 and R2+3, the closed cell m3, and the absence of m-cu. It is interesting that the long pedicel, the absence of arista or style on the tip of antenna, the absence of empodium may be the unique features of Orientisargidae and are found neither in Archisargidae nor in Kovalevisargidae . It is also interesting that the new family has a pair of foliaceous cerci on the female terminalia, which is only present in Uranorhagioninae (= Mostovskisarginae ) within Archisargidae (JF Zhang, 2010a).

As for m-cu is concerned, an alternative explanation is possible that a very short, but thick, rudimentary m-cu connecting CuA and flex point of M3+4 is present (see Figure 1F, G ). In such case, however, it becomes too short to measure.

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.