Plecia Wiedemann, 1828

Skartveit, John & Nel, André, 2017, Revision of fossil Bibionidae (Insecta: Diptera) from French Oligocene deposits, Zootaxa 4225 (1), pp. 1-83 : 36-38

Genus Plecia Wiedemann, 1828

In the 19th Century, fossil Plecia species were mostly placed in the genus Protomyia Heer , though many Penthetria species were also included in this genus.

Plecia assonensis Gentilini, 1993 ( Figs. 19, 107 – 109 )

Plecia assonensis Gentilini 1993: 161 .

Possibly a synonym of Plecia livida , but the pointed gonostylus might be diagnostic together with the straight, oblique vein R2+3 and the indistinctive pterostigma.

Material examined. (RGL) Dauphin 33, Bois d’Asson 34, Bois d’Asson 81

Localities. Bois d’Asson

Diagnosis. A small Plecia (wing length approximately 5 mm). Antennal flagellum 9-segmented. Vein R2+3 straight and oblique. Male gonostylus stout digitiform.

Redescription. Male: Total length 5.0– 8.5 mm (N=2, the former specimen obviously shrunk)

Head: Length 0.81 mm (N=1), width 0.86 – 1.21 mm (N=2). Antennal flagellum 9-segmented according to Gentilini (1993: 161), not possible to see in the specimens at hand.

Thorax: Length 1.7 – 2.9 mm (N=3), width 1.7 – 2.2 mm (N=2). Brown. Haltere pale.

Wing (fig. 107): Length 5.1 – 5.7 mm (N=3), width 1.7 – 2.5 mm (N=2), length/width = 2.31 – 3.01 (N=2). Pale brownish, almost hyaline, veins brown, slender, R-veins not notably stronger than posterior veins. Costa extends to a little beyond apex of R4+5. Subcosta fine, terminates approximately at fork of M, humeral vein present. Vein R 2+3 short, nearly straight and oblique, R4+5 slightly curved. Pterostigma small, light brown, indistinctive. Wing vein measurements in Table 2.

Legs: Light brownish, getting darker apicad. Hind femur apparently pale with darker apex.

Abdomen: Length 2.9 – 5.8 mm (N=3), width 0.9 – 1.4 mm (N=3). Brown, relatively broad.

Terminalia (figs. 108–109): Hypopygium 0.70 – 0.77 mm (N=3) wide, broad and robust. Gonostyli 0.35 – 0.46 mm (N=3), short, robust, apically pointed. Epandrium mesally with a shallow, V-shaped cleft.

Female unknown.

Fig. 108 . Male, terminalia, dorsal. RGFL Bois d’Asson 81. Fig. 109 . Male, terminalia. RGL Bois d’Asson 34.

Figures

FIGURES 107 – 109. Plecia assonensis Gentilini, 1993 Fig. 107. Male, wing. RGL Dauphín 33.