Bibio aquaesextiae, Skartveit, John & Nel, André, 2017

Skartveit, John & Nel, André, 2017, Revision of fossil Bibionidae (Insecta: Diptera) from French Oligocene deposits, Zootaxa 4225 (1), pp. 1-83 : 58-60

Bibio aquaesextiae sp. n.

(figs. 50, 162 – 164)

Material examined. Holotype (male) MNHN Aix 152.

Paratypes (males) MNHN Aix 610, 1294, 1436, 1452, (females) MNHN Aix 309, 416, 421, 532, 1010, 1014.

Localities. Aix-en-Provence

Diagnosis. A large (9 – 13.5 mm) Bibio with relatively slender body. Antennal flagellum 8-segmented. Wing hyaline with crossvein R-M nearly as long as basal section of Radial sector. Male hind tibia strongly clavate. Epandrium bilobate, gonostylus rather small.

Etymology. The species is named after Aquae Sextiae, the Roman colony which later developed into Aix-en- Provence.

Description. Male: Total length 8.5 – 12.0 mm (N=5). General body shape slender.

Head (fig. 163): Length 1.1 – 1.5 mm, width 1.2 – 1.7 mm (N=5). Compound eye large, intraocular pile not conspicuous. Ocelli rather small and widely spaced. Antenna slender, flagellum 8-segmented, 0.56 – 0.67 mm long (N=3).

Thorax: Length 2.3 – 2.6 mm, width 2.0 – 2.3 mm (N=5). Black. Haltere pale.

Wing (fig. 162): Length 6.4 – 8.9 mm, width 2.8 – 3.5 mm (N=5), length/width = 2.18 – 2.49 (N=5). Apparently hyaline, veins fine and concolourous with membrane. Pterostigma rather indistinctive. Crossvein R-M nearly as long as basal section of Rs. CuA1 and CuA2 apically curved. Wing vein measurements in Table 4 .

Legs: Probably pale coloured, relatively long. Fore tibia relatively slender. Hind tibia strongly clavate. Fore femur length 1.5 – 2.2 mm, width 0.55 – 0.66 mm (N=3), fore tibia length 1.6 – 2.0 mm (N=3), width 0.32 mm (N=1), hind femur 2.1 – 3.2 mm, width 0.43 – 0.55 mm (N=4), hind tibia 2.3 – 3.4 mm, width 0.53 – 0.62 mm (N=5).

Abdomen: Length 5.1 – 7.4 mm, width 1.4 – 1.9 mm (N=5). Long and slender, tapering apicad, brown.

Terminalia (fig. 164): Epandrium bilobate with rounded lobes, indentation between the lobes wide and Ushaped, laterally with a small indentation. Gonostyli relatively short. Ventrally with wide, rounded indentation between gonocoxites. Hypopygium width 0.8 – 1.1 mm (N=5), gonostylus length 0.40 – 0.47 mm (N=4).

Female: Total length 10 – 13.5 mm (N=5).

Fig. 163 . Male, head and thorax. MNHN Aix 152. Fig. 164 . Male, terminalia. MNHN Aix 152.

Head: Length 1.17 – 1.26 mm (N=3), width 0.93 – 1.31 mm (N=4). Rounded, compound eye relatively large, not protruding. Antennal flagellum 8-segmented.

Thorax: Length 2.3 – 2.5 mm (N=5), width 2.1 – 2.5 mm (N=4). Brown, haltere pale.

Wing: Length 7.7 – 9.8 mm (N=5), width 2.9 – 4.0 mm (N=5). Presumably hyaline, veins fine and concolourous with membrane. Pterostigma light brown, not very conspicuous. Venation as in male. Wing vein measurements in Table 4 .

Legs: Femorae brown, tibia and tarsi apparently lighter. Hind femur thick, clavate, hind tibia slender. Fore femur length 1.6 – 2.4 mm (N=4), width 0.73 – 0.81 mm (N=2), fore tibia length 1.9 – 2.2 mm (N=2), width 0.46 mm (N=1), hind femur length 2.2 – 3.5 mm (N=4), width 0.59 – 0.69 mm (N=4), hind tibia length 2.5 – 3.6 mm (N=4), width 0.41 – 0.58 mm (N=4).

Abdomen: Length 6.4 – 9.4 mm (N=5), width 2.1 – 3.2 mm (N=4). Relatively slender, cylindrical. Colour probably light brown.

Terminalia: Three spermathecae present as usual. Cerci small, rounded.

Discussion. None of the specimens at hand show good colour preservation and it is possible that colours have been considerably darker in life.

Figures

FIGURES 162 – 164. Bibio aquaesextiae sp. n. Fig. 162. Male, wing. MNHN Aix 152.

Tables

TABLE 4. Bibio spp., wing measurements

Measurement	aquaesextiae m	aquaesextiae f	baumbergeri m	baumbergeri f	curtisii m	curtisii f	major m	major f	spectabilis m	spectabilis f
Total length	6.3-8.7 (5)	7.7-9.8 (4)	6.8-7.7 (3)	8.0-10.7 (8)	6.2-8.5 (18)	8.1-9.9 (5)	5.3-8.0 (29)	7.9-10.5 (7)	5.8-6.9 (3)	6.7-10.6 (14)
Total width	2.8-3.5 (5)	2.9-3.6 (4)	2.8 (1)	2.8-3.6 (6)	2.7-3.5 (15)	3.2-3.5 (5)	2.4-3.6 (25)	2.9-3.7 (4)	2.5-2.8 (3)	3.0-4.3 (14)
MA-First branch of R	2.1-2.9 (5)	2.7-2.8 (2)	1.5 (1)	2.7-3.7 (7)	1.6-3.0 (11)	2.3-2.5 (4)	1.6-2.9 (24)	2.1-2.8 (3)	1.7-3.0 (3)	2.0-3.8 (13)
R 1	1.4-2.4 (5)	1.8-2.0 (2)	1.6 (1)	2.3-2.8 (4)	1.4-2.4 (11)	1.8-2.6 (4)	1.5-2.4 (27)	1.8-2.3 (3)	1.4-1.7 (3)	1.6-2.7 (13)
Rs	0.5-0.7 (5)	0.6-0.7 (2)	0.4 (1)	0.6-1.0 (8)	0.5-0.8 (11)	0.7-1.1 (4)	0.4-0.8 (26)	0.7-0.8 (3)	0.5-0.6 (3)	0.7-1.2 (13)
R 4+5	2.7-3.5 (5)	3.5-3.8 (2)	3.0 (1)	4.0-6.8 (8)	3.0-3.7 (11)	3.9-4.5 (4)	2.5-4.1 (22)	3.9-4.7 (3)	2.7-3.1 (3)	3.3-6.1 (11)
M basal to R-M	1.7-2.9 (4)	2.4-2.5 (2)	-	2.4-3.3 (6)	2.1-2.8 (11)	2.4-2.7 (4)	1.6-2.8 (19)	2.4-2.6 (2)	1.7-2.3 (3)	1.7-3.4 (13)
M distal to R-M	0.7-0.9 (2)	1.0-1.1 (2)	-	1.9-2.8 (4)	1.1-1.4 (10)	1.1-1.9 (4)	0.5-0.9 (9)	1.6 (1)	0.4-0.9 (3)	0.8-2.3 (11)
M 1	2.3-2.5 (2)	3.2-3.9 (2)	-	3.0-4.3 (4)	2.3-3.1 (10)	2.8-3.7 (4)	2.1-3.0 (8)	3.3 (1)	2.2-2.7(3)	2.5-3.4 (10)
M 2	2.1 (2)	2.7-3.3 (2)	-	2.6-3.9 (4)	1.9-2.5 (10)	2.2-3.2 (3)	1.8-2.7 (7)	2.9 (1)	1.9-2.3 (3)	1.9-3.0 (10)
R-M	0.26-0.40 (5)	0.41-0.50 (2)	0.14 (1)	0.15-0.34 (8)	0.07-0.12 (11)	0.13-0.21 (4)	0	0	0.09-0.19 (3)	0.16-0.32 (13)
M-Cu	0.40 (1)	-	-	-	0.40-0.62 (9)	0.57-0.67 (3)	-	0.80 (1)	0.4-0.5 (2)	0.5-0.8 (9)
CuA	1.1-1.2 (2)	1.6-2.0 (2)	1.1 (1)	2.4 (1)	0.9-1.1 (8)	1.5-2.0 (3)	0.8-1.6 (9)	1.7 (1)	0.8-1.3 (2)	1.4-2.2 (9)
CuA 1	3.7-4.4 (2)	4.5 (2)	2.6 (1)	3.7 (1)	3.1-4.1 (8)	3.3-4.9 (3)	2.9-3.9 (9)	3.9 (1)	3.0-4.0 (2)	3.3-5.1 (8)
CuA 2	2.8 (2)	2.6-2.9 (2)	1.8 (1)	2.1 (1)	2.3-3.5 (8)	2.2-3.2 (3)	1.8-2.9 (9)	2.8 (1)	2.1-2.8 (2)	2.4-3.7 (8)