Penthetria nervisinuata ( Théobald, 1937 ) Theobald, 1937

Skartveit, John & Nel, André, 2017, Revision of fossil Bibionidae (Insecta: Diptera) from French Oligocene deposits, Zootaxa 4225 (1), pp. 1-83 : 32-34

Penthetria nervisinuata ( Théobald, 1937) comb.n.

( Figs. 16 – 17, 98 – 102)

Plecia nervisinuata Théobald 1937: 407

Bibiopsis funebris Heer in Heer & Gaudin, 1861: 153 . (nec Penthetria funebris Meigen, 1804 ) (nomen nudum)

A medium-sized Penthetria , rather stocky for the genus, entirely black as usual for the genus. The shape of vein R2+3 is characteristic: it is vertical at base, then turns 90° and runs parallel to R4+ 5 in the basal half, then turns forwards, meeting Costa at an almost 45° angle.

Material examined. Holotype, female, FSL 391925 (fig. 14) from Aix. Paratype, female, FSL 391926.

Paratype, female, MNHN B 24519 from Céreste. Female, attributed by Heer to Bibiopsis funebris Heer (ETHZ 164).

Localities. Aix-en-Provence, Céreste.

Fig. 99 . Female, head and thorax, dorsal. ETHZ Aix 164. Fig. 100 . Female (?), wing, RGL Céreste 192.

Fig. 101 . Male, terminalia, dorsal. MNHN Aix 981. Fig. 102 . Male, wing. MNHN Aix 974.

Other material ( MNHN): Males: Aix 779, 884, 974, 1085, P26. Females: Aix 332, 428, 645, 752, 799, 890, 926, 965, 1013, 1061, 1322, 1337, 1347, 1404. (RGL) Céreste 662. Isolated wing: Céreste 192. Female, labeled 164 ( ETHZ, fig. 15).

Diagnosis. The species is easily recognized by the long, horizontal vein R2+3, which is sharply bent basally and a bit sinuous in the middle. It is the only species in the French Oligocene material with a typical Penthetria wing venation. Specimens with preserved pigmentation are entirely dark with blackish-fumose wings.

Redescription. Male: Total length 8.2 – 12.0 mm (N=5). The specimens are of a uniform, brown colour, probably not original colour.

Head: Length 0.96 – 1.30 mm (N=5), width 1.03 – 1.41 mm (N=4). Antenna robust, segments not possible to count.

Thorax: Length 2.2 – 2.9 mm (N=5), width 1.7 mm (N=1, smallest specimen).

Wing (fig. 102): Length 6.7 – 9.1 mm (N=4), width 2.2 – 2.9 mm (N=3), length/width = 2.98 – 3.30 (N=3). No pigment preserved in membrane, R-veins brown, posterior veins colourless. Costa extends to apex of R4+5. Humeral vein present, Subcosta terminating at origin of R2+3. Pterostigma oval, brown. R2+3 long, originating at base of pterostigma, bent in a right angle near base. Wing vein measurements in Table 1 .

Legs: Slender, first tarsomere of hind leg slightly swollen and spindle-shaped. Fore femur 2.2 mm (N=1), fore tibia 2.2 – 2.3 mm (N=2), hind femur 2.7 – 3.5 mm (N=3), hind tibia 2.5 – 3.8 mm (N=3).

Abdomen: Length 5.4 – 8.0 mm (N=5), width 1.1 – 1.6 mm (N=2). Cylindrical.

Terminalia (fig. 101): Gonostylus digitiform, curved, pointed. Epandrium wide, dome-shaped. Hypopygium width 0.83 – 1.15 mm (N=4), gonostylus length 0.43 mm (N=1).

Female: Total length 7.5 – 12.0 mm (N=16). Holotype and one paratype very dark, probably the original colour. Most of the other specimens have little or no pigment preserved.

Head (fig. 99): Length 0.77 – 1.16 mm (N=11), width 0.82 – 1.28 mm (N=17). Rounded. Compound eye medium-sized, slightly protruding. Ocellar triangle prominent but not very tall. Antenna robust, flagellum probably 8-segmented.

Thorax: Length 1.9 – 3.1 mm (N=16), width 1.7 – 2.6 mm (N=15). Sulci prominent. Haltere dark brown.

Wing (figs. 98, 100): Length 7.0 – 10.5 mm (N=18), width 2.7 – 3.9 mm (N=16), length/width = 2.44 – 3.00 (N=14). Blackish fumose, R-veins dark, posterior veins concolourous with membrane. Costa terminates at apex of R4+5. Humeral vein present, Subcosta terminating at or slightly beyond origin of R2+3. Pterostigma oval, black. CuAveins conspicuously strong. Vein R2+3 long and sinuous, basally vertical, bent 90° and then running parallel to R4+5 before bending toward costa in distal half. Relative length of stem and fork of CuA apparently quite variable. CuA2 apically curved basad. Wing vein measurements in Table 1 .

Legs: Slender, covered with short erect dark pile. Length of fore femur 2.0 – 2.6 mm (N=5), fore tibia 1.8 – 2.6 mm (N=6), hind femur 2.1 – 3.1 mm (N=5), hind tibia 1.9 – 3.5 mm (N=6).

Abdomen: Length 5.1 – 8.3 mm (N=14), width 1.9 – 2.8 mm (N=13). Cylindrical.

Terminalia: Three spermathecae present. Cerci two-segmented, small and slender.

Figures

FIGURE 16. Penthetria nervisinuata, female. Holotype of Plecia nervisinuata Théobald, FSL 391925. FIGURE 17. Penthetria nervisinuata, female. ETHZ, labeled 164.

FIGURES 98 – 102. Penthetria nervisinuata (Théobald, 1937) Fig. 98. Female, wing. ETHZ Aix 164.