Bibio spectabilis Théobald, 1937

Skartveit, John & Nel, André, 2017, Revision of fossil Bibionidae (Insecta: Diptera) from French Oligocene deposits, Zootaxa 4225 (1), pp. 1-83 : 72-74

Bibio spectabilis Théobald, 1937

(figs. 68, 198 – 206)

Bibio spectabilis Théobald, 1937: 333 .

Material examined. Holotype (female) of Bibio spectabilis FSL 391911. Paratype (female) of Bibio spectabilis FSL 391912.

Fig. 199. Male, wing. MNHN Aix 1436.

Fig. 200. Male, habitus. MNHN Aix 313.

Fig. 201. Male, head and thorax. MNHN Aix 1436.

Fig. 202. Male, hind leg. MNHN Aix 1377.

Fig. 203. Male, terminalia. MNHN Aix 1436.

Fig. 204. Female, head and thorax. MNHN Aix 1299. Fig. 205. Female, hind leg. MNHN Aix 845.

Fig. 206. Female, terminalia. MNHN Aix 845.

Additional material: Male (tentatively associated) EM 70215 (1.2.2) (stored in FSL). Males (MNHN Aix 52, 1377). Females (MNHN Aix 6, 10, 11, 107, 161, 309, 845, 1090, 1299, 1307, 1446, 1447, P25).

Localities. Aix-en-Provence

Diagnosis. A medium-sized to large (8.5 – 12 mm), robust Bibio species. The wing has a short but distinctive R- M crossvein, about one fifth as long as basal part of R s, and CuA1 and CuA2 are apically straight or nearly so. Antenna robust with 8-segmented flagellum. Male epandrium not bilobate, apically straight with slightly protruding posterior corners.

Redescription. Male (tentatively associated, fig. 200): Total length 9.0 – 10.0 mm (N=3).

Head (fig. 201): Length 1.3 – 1.6 mm (N=2), width 1.5 mm (N=1). Dark brown, presumably black in life. Antennal flagellum 8-segmented. Palp relatively short and robust. Ocellar triangle large and prominent.

Thorax: Length 2.8 – 3.1 mm (N=2), width 2.3 mm (N=1). Dark brown, presumably black in life. Haltere pale.

Wing (fig. 199): Length 5.8 – 6.9 mm (N=3), width 2.5 – 2.8 mm (N=3), length/width = 2.31 – 2.73 (N=3). Hyaline? Membrane pigmentation not well preserved, veins distinctive throughout. R4+5 arched forwards, running more or less parallel to Costa in distal half. Crossvein R-M short but distinctive. CuA-veins apically straight or nearly so. Wing vein measurements in Table 4 .

Legs (fig. 202): Fore tibia with spur a little less than half as long as anterior spine. Hind femur stout, clavate. Hind tibia rather short and robust with long, curved, apically blunt spur. Hind tarsus robust, first tarsomere approximately three times as long as wide. Hind femur length 2.5 – 2.7 mm (N=3), width 0.52 – 0.60 mm (N=3), hind tibia length 2.3 – 2.9 mm (N=3), width 0.40 – 0.44 mm (N=3).

Abdomen: Length 5.8 – 6.2 mm (N=3), width 1.3 mm (N=1). Dark brown, presumably black in life, conical.

Terminalia (fig. 203): Hypopygium width 0.92 – 1.10 mm (N=2). Epandrium not bilobate, posterior margin nearly straight with rounded, slightly protruding posterior corners. Gonostylus large and robust.

Female: Total length 9.3 – 12.0 mm (N=13)

Head (fig. 204): Length 1.19 – 1.39 mm (N=6), width 0.93 – 1.32 mm (N=6). Black. Antennal flagellum 0.55 – 0.62 mm long (N=2), 8-segmented. Ocellar tubercle small and low. Palp short and robust. Compound eye rather small, about one third length of head.

Thorax: Length 2.8 – 3.8 mm (N=13), width 2.1 – 3.1 mm (N=5). Haltere dark brown.

Wing (fig. 198): Length 6.7 – 10.6 mm (N=14), width 3.0 – 4.3 mm (N=14), length/width = 2.08 – 2.62 (N=14). Grayish hyaline, pterostigma oval, dark brown, wing mesally with a chocolate-brown band stretching from the origin of R s distad to pterostigma, posteriorly to CuA1.Crossvein R-M short but distinctive, about one fifth as long as basal section of R s. The CuA-veins apically straight or nearly so. Wing vein measurements in Table 4 .

Legs (fig. 205): femorae and tibiae brownish yellow, tibiae apically darker. Fore femur relatively slender, about three times as long as wide in lateral view. Fore tibia with spur about one third the length of anterior spine. All tarsi slender, tarsomeres brownish yellow, apically darkened. Hind femur slightly clavate, hind tibia slender. Metatibial spur rather long, blunt. Fore femur length 1.8 – 2.4 mm (N=9), width 0.69 – 0.86 mm (N=7), fore tibia length 1.7 – 2.4 mm (N=11), width 0.46 – 0.47 mm (N=2), hind femur length 2.6 – 3.6 mm (N=11), width 0.54 – 0.76 mm (N=9), hind tibia length 2.7 – 3.9 mm (N=11), hind first tarsomere 1.0 – 1.2 mm (N=5).

Abdomen: Length 6.1 – 9.2 mm (N=15), width 2.5 – 2.8 mm (N=6). Blackish brown.

Terminalia (fig. 206): Cercus slender, rounded. It may appear to have two segments but this is probably an artefact.

There is also a specimen in FSL (FSL 391912) labeled as a paratype of B. spectabilis . This specimen, however, has a slender fore tibia and a distinctive vein R2+3 and belongs in the genus Plecia . In ETHZ there is a female specimen labeled “ Bibio spectabilis Heer ” (ETHZ Pl. I 855) from the Miocene site of Öhningen. The specimen actually belongs to Bibio moestus ( Skartveit & Pika 2014) , and the name Bibio spectabilis Heer was apparently never formally published and so does not affect the nomenclature of this species. Using the dark-banded wings as an identification character is problematic since the vast majority of the specimens from Aix-en-Provence have no preserved wing pigmentation.