Bibio auripes Statz, 1943

Skartveit, John & Wedmann, Sonja, 2021, A Revision of fossil Bibionidae (Insecta: Diptera) from the Oligocene of Germany, Zootaxa 4909 (1), pp. 1-77 : 41

Bibio auripes Statz, 1943 (figs. 64–66, 177–180)

Bibio auripes Statz, 1943: 51 .

Bibio Ƌ Nr. 2 Statz, 1943: 53.

Localities: Rott

Material examined: Holotype, (female) of Bibio auripes LACMIP 2533.233ab. Additional material (males) LACMIP 2533.227ab/ LACMIP Type 3357 (part and counterpart, specimen described by Statz (1943)), LACMIP 2533.1067ab.

Description:

Female (N=1, figs. 64, 177):

Total length without head 9.8 mm

Head: Missing

Thorax: Length 3.4 mm, width 2.7 mm. Brownish-black.

Legs: femora and tibiae pale yellowish, tibiae with dark tip, tarsi dark brown. Fore tibia 1.9 mm long, 0.5 mm wide, stout, spur about half as long as spine. Hind femur stout, hind tibia and tarsus slender. Hind tibia 3.5 mm long, 0.5 mm wide.

Wing: Length 9.8 mm. Brown fumose, veins dark brown. Pterostigma dark brown, distinctive. Costa extends to apex of R 4+5. Subcosta straight , fairly distinctive. Humeral vein not apparent. Basal Rs almost reaches M, crossvein R-M very short. Vein measurements are given in Table 5 .

Abdomen: Length 6.9 mm, width 2.6 mm. Blackish-brown, apically truncate, slightly conical. Cerci small and rounded.

Male (N=2, Figs. 65–66, 178–180, provisionally associated):

Total length 10.5–11.0 mm (N=2)

Head (fig. 179): Length 1.8 mm (N=2), width 1.7 mm (N=1). Black. Antenna rather short, cylindrical, flagellum 0.66 mm long, 0.16 mm wide (N=1), probably 6-segmented. Palpus rather slender, last segment cylindrical.

Thorax (fig. 179): Length 2.9–3.3 mm (N=2), width 2.6 mm (N=1). No pigmentation preserved.

Legs: Only scattered pigmentation preserved but probably dark brown or black. Fore femur 2.0 mm long, 0.7 mm wide (N=1), relatively slender, fore tibia 2.0 mm long (N=1), spindle-shaped with rather short spine, spur quite short. Fore tarsus robust. Hind leg with femur and tibia strong, first tarsomere thick. Hind femur 2.3–2.9 mm long (N=2), 0.5–0.6 mm wide (N=2), hind tibia 2.5–2.9 mm long (N=2), 0.4–0.6 mm wide (N=2).

Wing: Length 7.2–8.2 mm (N=2). Hyaline, R-veins brown, posterior veins colourless. Wing venation mostly not preserved.

Abdomen (fig. 180): Length 6.4–7.0 mm (N=2). Black, slightly conical. Densely covered by short, dark pile.

Terminalia: No pigmentation preserved. Epandrium with wide, V-shaped cleft, lobes rounded. Gonostyli rather short. Hypopygium width 1.0– 1.3 mm (N=2).

Discussion:

The type of Bibio auripes and male specimens assigned to Bibio sp. 2 agree well in wing venation (the parts that can be observed in the auripes holotype) and size. The wing venation is also rather similar to that which can be seen in the holotype of Bibio compta and the two may possibly be synonyms, however the size difference between the two is substantial, close to the extremes of size variation found within a species in recent bibionids. Unfortunately, the types of both auripes and compta are poorly preserved, a thorough comparison of the two is not possible.