Penthetria gigantea ( 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 : 24

Penthetria gigantea ( Théobald, 1937) comb.n.

(Figs. 6 – 9, 78 – 80)

Plecia gigantea Théobald, 1937: 226 – 227.

Plecia crassiventris Théobald, 1937: 227 . Syn.n. Plecia miegi Théobald, 1937: 232 – 233. Syn.n. Plecia luteipennis Théobald, 1937: 233 . Syn.n.

Material examined. Holotype (female) of Plecia gigantea NMB F1380, (fig. 6). Paratypes (females) of Plecia gigantea NMB F460, F1388. Holotype (female) of Plecia crassiventris NMB F1381, (fig. 7). Paratypes (females) of Plecia crassiventris NMB F1389/1, F1389/2. Holotype (male) of Plecia miegi NMB F1399 (fig. 8), part + counterpart. Paratypes (males) of Plecia miegi NMB F1400, F1401. Holotype (male) of Plecia luteipennis NMB F1402/F2420 (fig. 9) (part and counterpart of same specimen). Paratype (male) of Plecia luteipennis NMB F1413.

Localities. Kleinkembs.

Diagnosis. A large (8–13.5 mm) and slender Penthetria with relatively long and slender legs. Antennal flagellum probably 8-segmented. Male epandrium subtriangular, gonostylus conical, apically slender. Wing yellowish fumose in male, brownish in female. Vein R2+3 nearly straight with a small bend in middle.

Redescription. Male: Total length 8.0 – 13.5 mm (N=4). Entirely black.

Head: Length 1.1 – 1.5 mm (N=4), width 1.1 mm (N=2). Antennal flagellum cylindrical, approximately 8- segmented.

Thorax: Length 2.1 – 3.0 mm (N=4), width 1.7 – 2.4 mm (N=2). Haltere dark brown.

Wing (fig. 78): Length 9.1 – 11.6 mm (N=3), width 3.2 – 3.4 mm (N=2), length/width = 3.02 – 3.40 (N=3). Light brown fumose with brown R-veins, posterior veins colourless. Costa extends some distance beyond apex of R4+5. Humeral vein present, Subcosta long and horizontal. R2+3 rather straight, oblique. Pterostigma inconspicuous. Basal part of Rs subparallel to M. Fork of M relatively long. Wing vein measurements in Table 1 .

Legs: relatively long and slender, dark brown. Femorae slightly clavate. Femur 1 length 3.2 – 3.6 mm (N=2), tibia1 length 3.3 – 3.6 mm (N=2), femur 3 length 3.4 – 4.5 mm (N=3), tibia 3 length 3.8 – 4.3 mm (N=2).

Abdomen: Length 4.6 – 9.6 mm (N=5), width 1.0 – 1.4 mm (N=2). Brown, slender, cylindrical. Abdominal pile rather short.

Terminalia (fig. 80): Epandrium rather small, subtriangular. Gonostylus robust, almost straight, sharply pointed. Hypopygium width 1.3 – 1.5 mm (N=2), gonostylus length 0.64 – 0.67 mm (N=2).

Female: Total length 9.2 – 13.5 mm (N=4). Entirely black.

Head: Length 0.9 – 1.2 mm (N=3), width 0.7 – 1.0 mm (N=2). Relatively small, oval, longer than broad. Compound eyes do not protrude. Antennal flagellum cylindrical, probably eight-segmented.

Thorax: Length 2.8 – 4.6 mm (N=6), width 2.3 – 3.2 mm (N=4). Black. Sulci deep and conspicuous. Pile not conspicuous. Haltere yellowish-brown.

Wing (fig. 79): Length 9.4 – 11.5 mm (N=6), width 3.0 – 3.8 mm (N=3), length/width = 2.95 – 3.77 (N=4). Brown fumose. Radial veins light brown, strong, more posterior veins fine and inconspicuous. Pterostigma invisible. Venation as in male. Wing vein measurements in Table 1 .

Legs: Dark brown. Long and slender, femorae slightly clavate. Tibia 3 length 5.1 mm (N=1).

Abdomen: Length 5.9 – 8.1 mm (N=3), width 2.5 – 3.2 mm (N=4). Dark brown, cylindrical. Pile not conspicuous.

Terminalia: Cercus two-segmented as usual for genus, rather small, pointed.