Bibio xylophilus Germar, 1837

Skartveit, John & Wedmann, Sonja, 2021, A Revision of fossil Bibionidae (Insecta: Diptera) from the Oligocene of Germany, Zootaxa 4909 (1), pp. 1-77 : 52-53

Bibio xylophilus Germar, 1837 (figs. 82, 205–207)

Bibio xylophilus Germar 1837: 22 .

Localities: Orsberg, Enspel.

Material examined: Holotype (female) of Bibio xylophilus STIPB A 600 (fig. 82).

Additional specimen: One female specimen labeled as Bibio xylophilus on display in STIPB, not studied. Male: GDKE PE 2010 5895 Female: GDKE PE 1995 6196. Sex uncertain: STIPB A 608 (Germar material, labeled as Bibio sp.).

Description:

Female (N=2, figs. 82, 205–207):

Total length 10.5 mm.

Head (fig. 207): Length 1.6 mm. Oval. Complex eye oval, about half as long as head. Ocellar triangle rather small and incospicuous. Antenna and palpus slender, flagellum 0.69 mm long, probably 7-segmented, last palpomere cylindrical. Mouthparts not at all protruding.

Thorax (fig. 207): Length 3.1 mm. Black, haltere brown.

Wing (fig. 206): Length 8.4 mm, width 3.0 mm, length/width = 2.85. Colour and venation as in male. Vein measurements are given in Table 5.

Legs: Fore femur length 2.0 mm, hind femur length 3.9 mm, width 0.83 mm, hind tibia length 3.4 mm, width 0.65 mm.

Abdomen: Length 7.0 mm, width 2.3 mm. Spindle-shaped.

Male (N=1):

Total length 9.0 mm.

Head: Length 1.6 mm. Broadly oval. Antennal flagellum 0.45 mm long, slender, segments difficult to count in specimens at hand. Palpus 0.90 mm long, slender, last segment cylindrical. Ocellar tubercle small, not prominent. Pile not preserved in specimens at hand.

Thorax: Length 2.7 mm. Entirely black. Haltere brown.

Wing: Length 5.4 mm, width 2.3 mm, length/width = 2.4. Membrane colour variable in the specimens at hand, but this is probably due to taphonomical reasons, wings with well-preserved pigment are brown fumose with dark costal cells, apex a little paler. Pterostigma brownish-black, oval, distinctive. Humeral crossvein absent. Costal cell rather wide. Costa reaches to apex of R 4+5. Basal Radial sector 3–4 times as long as crossvein R-M. Crossvein M-Cu joins M 2 just distad of furcation. Vein measurements are given in Table 5.

Legs: Dark brown, femora somewhat paler. Fore femur 1.8 mm long, more than twice as long as wide. Fore tibia with rather short spine, about one fourth of tibia length. Hind femur 2.8 mm long, 0.55 mm wide, rather strongly clavate, hind tibia 2.7 mm long, 0.55 mm wide, clavate, first hind tarsomere 1.1 mm long, 0.42 mm wide, distinctively swollen.

Abdomen: Length 5.3 mm. Rather robust, cylindrical.

Terminalia: Hypopygium width 1.1 mm, not clearly visible in any of the specimens at hand, but gonostylus apparently quite short and robust, rather wide at base. Epandrium apically with shallow, V-shaped indentation.

Discussion:

This species was placed in genus Protomyia by Heyden & Heyden (1865 a) and, based on the published information, in genus Penthetria by Statz (1943: 42). There appears to have been a considerable confusion as to the identity of this species, some authors (e.g. Unger 1841) have identified specimens of other genera or species (in Unger’s case, even an non-bibionid) as this species, but there is no indication of any of them having studied the type. The type specimens have little preserved pigment, pale brownish. Body outline and wing venation are readily visible, details of body anatomy not. Specimens of both sexes from Enspel have brownish-black bodies and dark brown legs.

Genus Bibiodes Coquillett, 1904