Bibio compta 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 : 44-45

Bibio compta Statz, 1943 (figs. 70, 190)

Bibio compta Statz, 1943: 52 .

? Bibio ♂ Nr. 6 Statz, 1943: 55

Localities: Rott

Material examined: Holotype, female, LACMIP 2533.236ab / LACMIP Type 3366 (fig. 70). One auchenorrhynchan on the same slab. We did not find the specimen of Bibio Ƌ Nr. 6 in LACM, its inclusion here is based on its wing venation and size.

Description:

Female (N=1, figs. 70, 190):

Total length without head 6.5 mm

Head not visible (folded back over thorax)

Thorax: Length 2.0 mm, width 1.8 mm. Dark brown. Notaulices deep and distinctive.

Legs: femora dark brown, tibiae pale with brown tips. Fore tibia stout with short spur. Hind femur 1.9 mm long, 0.47 mm wide, stout, hind tibia 2.0 mm long, 0.37 mm wide, slender.

Wing: Length 5.8 mm, width 2.1 mm, length/width = 2.8. Hyaline, anterior veins pale brown, posterior veins colourless. All veins very fine. Pterostigma light brown, indistinctive. Subcosta long, straight, fine and indistinctive. Costa extends to apex of R 4+5. R-M very short, basal Rs about five times as long as R-M. Vein measurements given in Table 5.

Abdomen: Length 4.8 mm, width 1.9 mm. Brown, slightly spindle-shaped. Cerci small and rounded.

Male (no material found), description based on text and figures in Statz (1943):

Total length without head 7.8 mm. Black.

Head: not preserved in the specimen.

Thorax: Length 2.6 mm, oblong-oval, with transverse microsculpture and black pile.

Legs: Black, robust, fore femur short, stout and flattened, hind leg robust with long, black pile, hind tarsus not thickened.

Wing: Length 6.3 mm, width 2.1 mm, length/width = 3.0. Hyaline with brown veins throughout and brown pterostigma. Subcosta weak and indistinctive. Radial sector extends to vein M, no crossvein R-M, but no fusion of Rs and M as in genus Bibiodes . R 4+5 lightly curved. M-veins curved a little basad, M-Cu meets M 2 a little distad of furcation. CuA-veins apically rather straight. CuP weak and indistinctive. Vein measurements given in Table 5.

Abdomen: Rather slender, conical.

Terminalia: Hypopygium width 1.3 mm. Gonostylus curved digitiform as usual for genus.

Discussion:

The type specimen is quite badly preserved and scarcely recognisable at the species level. The very short R-M crossvein combined with small size (notably smaller than the also poorly preserved Bibio auripes ) suggests it might be a valid species, but this is difficult to ascertain.