Bibio major ( Oustalet, 1870 ) Oustalet, 1870

Skartveit, John & Nel, André, 2017, Revision of fossil Bibionidae (Insecta: Diptera) from French Oligocene deposits, Zootaxa 4225 (1), pp. 1-83 : 67-71

Bibio major ( Oustalet, 1870) comb.n.

(Figs. 65 – 67, 188 – 197)

Plecia major Oustalet, 1870: 114

Bibio inflexus Théobald, 1937: 404 .

Material examined. Plecia major syntype (male) MNHN R 0 6693. Bibio inflexus holotype (female) EEFN Coll. Fliche F 273–274.

Additional material: 41 males: UPMC Céreste 75; (all following RGL, currently stored in MNHN) Céreste 34, 74, 87, 90, 223, 269, 316, 338, 353, 554, 644, 649, 660, 664, 665, 666, 718, 896, 991, 992, 993, 995, 1000, 1019, 1026, 1029, 1030, 1116, 1144, 1166, 1419, 1742, P91, P188, P254, P353, P452, P516, P526, P539. 36 females: Céreste 54, 68, 76, 275, 568, 639, 641, 653, 654, 655, 656, 667, 1011, 1018, 1020, 1021, 1027, 1028, 1099, 1100, 1111, 1134, 1360, 1574, 1655, 1672, 1685, 1697, P316, P358, P418, P461, P519, P534, P543, P551.

Localities. Corent, Céreste.

Fig. 185. Female, habitus. NMB F1383.

Fig. 186. Female, head and thorax. NMB F1386/2. Fig. 187. Female, terminalia, ventral. NMB F1385/4.

Fig. 189. Female, wing. RGL Céreste 655.

Fig. 190. Male, habitus. MNHN Aix 313.

Fig. 191. Male, habitus. RGL Céreste 1029. Fig. 192. Female, habitus. MNHN Aix 1286.

Fig. 193. Male, head. MNHN Aix 313.

Fig. 194. Male, fore leg. MNHN Aix 313.

Fig. 195. Male, hind leg. MNHN Aix 89.

Fig. 196. Male, terminalia, dorsal. RGL Céreste 34. Fig. 197. Female, terminalia, ventral. MNHN Aix 2.

Diagnosis. a medium-sized to large (8.5 – 13 mm) Bibio species. Head conspicuously small, width in male about half of thorax width, flagellum slender and 10-segmented. Wing hyaline, vein Rs dips toward M so that crossvein R-M is obliterated, but the two veins are not fused for any distance like in the genus Bibiodes . Pterostigma small, dark and distinctive. Male legs entirely dark, fore tibia with spur approximately half as long as anterior spine, hind femur thick and spindle-shaped, hind tibia rather slender, not clavate, apically truncate. Male epandrium small and not bilobate. Female body dark, legs mostly pale-coloured.

Redescription. Male (figs. 190–191): Total length 8.5 – 11.2 mm (N=31). Entirely black, body pile not conspicuous.

Head (fig. 193): Length 0.87 – 1.35 mm (N=10), width 0.98 – 1.35 mm (N=9). Conspicously small, width approximately half of thorax width. Flagellum 10-segmented, length 0.49 – 0.68 mm (N=5).

Thorax: Length 2.4 – 3.4 mm (N=20), width 2.0 – 2.8 mm (N=5). Black. Haltere pale brownish.

Wing (fig. 188): length 6.2 – 8.0 mm (N=9), width 2.7 – 3.4 mm (N=5), length/width = 2.12 – 2.60 (N=5), hyaline, R-veins brown, posterior veins colourless. Pterostigma small, dark and distinctive. Wing vein measurements in Table 4 .

Legs (figs. 194–195): Black. Mid- and hind femorae moderately clavate, hind tibia rather slender, straightsided, apically truncate. Hind first tarsomere slender to moderately robust. Fore femur length 1.4 – 2.0 mm (N=5), width 0.53 – 0.65 mm (N=5), fore tibia length 1.5 – 1.6 mm (N=5), fore first tarsomere length 0.9 – 1.4 mm (N=4), hind femur length 2.3 – 3.5 mm (N=20), width 0.51 – 0.65 mm (N=13), hind tibia length 2.3 – 3.1 mm (N=22), width 0.34 – 0.55 mm (N=14), hind first tarsomere length 0.81 – 0.93 mm (N=6).

Abdomen: Length 5.2 – 7.1 mm (N=10), width 1.2 – 1.6 mm (N=8). Black.

Terminalia (fig. 196): Hypopygium width 0.85 – 1.06 mm (N=8). Epandrium rather small, posteriorly concave but not bilobate, posterior corners slightly protruding. Gonostyli robust, quite long, of the typical shape for genus.

Female (fig. 192): Total length 10.0 – 13.0 mm (N=12).

Head: Length 1.03 – 1.30 mm (N=7), width 1.13 – 1.43 mm (N=7), quite short and broad. Flagellum 10- segmented, length 0.67 – 0.84 mm (N=5).

Thorax: Length 3.2 – 4.5 mm (N=11), width 2.4 – 3.2 mm (N=5).

Wing (fig. 189): Length 7.9 – 10.5 mm (N=6), width 2.9 – 3.7 mm (N=4), length/width = 2.42 – 2.71 (N=4). Hyaline, venation as in male. Pterostigma small and dark, distinctive. Wing vein measurements in Table 4 .

Legs: Legs mostly pale. Fore femur 2.1 – 2.4 mm long (N=2), 0.76 – 0.79 mm wide (N=2), fore tibia 2.1 – 2.3 mm long (N=3), fore first tarsomere 1.5 mm (N=1), hind femur 2.9 – 3.6 mm long (N=4), 0.61 – 0.70 mm wide (N=5), hind tibia 3.1 – 3.6 mm long (N=6), 0.40 – 0.49 mm wide (N=4), hind first tarsomere 1.0 – 1.2 mm (N=3).

Abdomen: Length 6.0 – 8.6 mm (N=11), width 2.1 – 3.1 mm (N=7).

Terminalia (fig. 197): Last sternite with a narrow and shallow indetation.

The wing venation of this species approaches the typical venation of the genus Bibiodes Coquillett , which, though only found in the Nearctic region in the recent fauna, is known from several European fossils ( Skartveit 2009). Unfortunately, in most of the specimens from Céreste and Aix-en-Provence the wing venation is not visible. But the male genitalia are typical of the genus Bibio and R s and M just meet without really merging, hence it is classified as a Bibio species.