Bibio Geoffroy, 1762

Skartveit, John & Nel, André, 2012, Fossil Bibionidae (Diptera: Bibionomorpha) from the late Oligocene of Bes-Konak, Anatolia, Turkey, Zootaxa 3329, pp. 51-63 : 52-58

Genus Bibio Geoffroy, 1762

Bibio Goeffroy, 1762: 568 . Type species, Tipula hortulana Linnaeus, 1758 (by subsequent designation of Latreille 1810: 442, validated by I.C.Z.N., 1957: 86).

Bibio anatolicus sp. n. (figs. 1–14)

Etymology: Named after Anatolia, home province of the Bes-Konak outcrop.

Diagnosis: A moderately large Bibio species. Wing light brown fumose, rather narrow, crossvein r-m approximately half as long as Rs. Antennal flagellum seven- or eight-segmented. Hind legs moderately clavate with first tarsomere not swollen. Lobes of epandrium short and widely separated.

Material: Holotype (male) MNHN B 47826, fig.1. The specimen is preserved lying on its side, but with the abdomen twisted so that the terminalia are seen from a dorsal view. Preservation of wings, body and hind legs quite good, of head and terminalia fair. The two front pairs of legs are poorly preserved. Pile of head and body not preserved.

Other material, all in MNHN: five males (B 47751, B 47833, B 48011, IY 262, 1 unlabelled) 20 females (BK 32, BK 92, BK 345, BK 605, BK 642, B 47578, B 47603, B 47728, B 47747, B 47771, B 47776, B 47789, B 47820, B 47884, B 47906, B 47926, B 47932, B 47972, B 48014, 1 unlabelled).

Description: Male: A moderately large species, body 8.0– 8.7 mm long (N = 4), black with brownish legs. Head ( Fig. 2 ) 1.45–1.60 mm long (N = 3), plus rostrum and proboscis 0.75 mm (N = 1). Flagellum apparently seven-segmented, but not well preserved in any of the male specimens. Pile not preserved.

Thorax black. Pile not preserved. Length 2.75–3.25 mm (N = 3).

Legs: Brownish. Fore femur with long, black setae, tibia 1.85 mm long (N = 1). Shape of mucron and spur of fore tibia not possible to see well in any of the male specimens. Hind femur and tibia ( Fig. 3 ) strongly clavate. Hind femur dark basally, light yellowish-brown in apical half, 2.75–3.0 mm (N = 3) long, 0.19–0.25 mm (N = 3) wide basally, 0.48–0.57 mm (N = 4) apically. Hind tibia yellowish-brown basally, darkened apically, 2.6–2.9 mm (N = 4) long, 0.22–0.28 mm (N = 4) wide basally, 0.48–0.62 mm (N = 4) apically. First tarsomere slightly swollen, 0.96 mm long, 0.32 mm wide (N = 1).

Wing ( Fig. 4 ) 6.3–7.6 mm long (N = 5), 2.5–2.75 mm wide (N = 2). Light brown fumose, veins distinctive throughout, R-veins brown, more posterior veins more or less colourless. Pterostigma brown and distinctive. Crossvein r-m is roughly half as long as first sector of Rs.

Abdomen 4.4–5.0 mm long (N = 3), relatively slender, somewhat conical, tergites short and transverse. No trace of pile in the specimens at hand. Epandrium ( Fig. 5 ) with two short, rounded lobes separated by a wide mesal cleft. Gonocoxosternite ( Fig. 6 ) with a wide and shallow, mesal indentation. Gonostyli sickle-shaped, rather small and slender.

Female (fig. 7): Body 10.2–12.7 mm long (N = 5). Head ( Fig. 8 ) 1.5–2.0 mm long (N = 4), black, antennal flagellum ( Fig. 9 ) rather short and stout, eight-segmented. Ocellar tubercle prominent.

Thorax 3.8–4.0 mm long (N = 3), yellowish-brown to dark brown dorsally, pleura darker. Legs brown, fore tibiae black, mid- and hind tibiae and all tarsal segments darker apically; fore tibia ( Fig. 10 ) quite stout, spur short and curved, less than half as long as mucron. Mid- and hind femora clavate, rather thick, hind tibia slender, all tarsi slender. Hind leg as in Fig. 11 .

Wing ( Fig. 12 ) 8.0– 9.5 mm long (N = 5), light brown fumose, venation as in male, veins brown, distinctive throughout. Pterostigma brown, distinctive.

Abdomen yellowish-brown to dark brown. Terminalia as in Figs. 13–14 . Cerci rounded.

Remark: The antenna is well preserved in just one of the specimens at hand (female, MNHN B 47906, Fig. 9 ). In this case the flagellum consists of eight short, transverse segments. In several other specimens (e.g., Fig. 2 ), the flagella appear to have just six or seven segments; they are, however, too fragmentary for a certain count.

Bibio nigricosta sp. n. (figs. 15–21)

Etymology: The species has a conspicuously darkened costal cell in the wing and is named accordingly. From Latin niger, black, and costa, rib. The species epithet is a noun in opposition.

Diagnosis: A large, robust species. Femorae red with black tips, tibiae and tarsi black. Wing rather short and broad, fumose with costal cell darkened, pterostigma black. Crossvein r-m half as long as to subequal to first sector of Rs. Legs robust, first hind tarsomere moderately swollen. Male gonostyli robust, epandrium rather small with rounded lobes.

Remark. The species appears to be similar to Bibio giganteus Heer, 1849 , Bibio linearis Heer, 1849 , and Bibio partschii Heer, 1849 described from the Early Miocene of Radoboj ( Croatia). It can be distinguished from these species by the much broader wing (length/width approximately 2.1 versus 2.7 in Bibio giganteus and B. partschii ). The latter species also have crossvein r-m markedly shorter than half the length of first sector of Rs. The comparison is somewhat complicated by the fact that Heer’s three species were described based on females, while the type of B. nigricosta is a male. However, female bibionids tend to have slightly wider, not narrower, wings than males. We did not find the type of Bibio linearis , but judging from Heer’s description we believe that it is very similar to Bibio giganteus and B. partschii .

Material. Holotype (male) BK 450, fig. 15. The specimen is preserved in a spread position, dorsal side up. The head is poorly preserved but body, hind legs and wings are in a fairly good state of preservation. The two anterior pairs of legs are poorly preserved. Paratype: one female (B 47847), fig.19. Other material: partial specimen, sex uncertain (BK 21), one wing, presumed female (B 47961).

Description: Holotype (male) BK 450. Total length of holotype 13.1 mm; colour black except for reddish femora. Body pile apparently short and fine. Head 1.95 mm wide, 2.05 mm long (including rostrum), poorly preserved. Antennal flagellum poorly preserved but probably seven-segmented.

Thorax 3.5 mm long, 2.15 mm wide.

Wing ( Fig. 17 ) 7.1 mm long, 3.35 mm wide, brown fumose, costal cell from pterostigma and two thirds of distance basad dark. Pterostigma brownish-black, distinctive. Veins distinctive throughout. Crossvein r-m approximately half as long as radial sector. Crossvein m-cu not visible in type.

Hind leg ( Fig. 16 ): Femur 2.6 mm long, 0.68 mm wide, reddish (probably bright red in life), clavate. Tibia 3.0 mm long, 0.64 mm wide, black, truncate apically. First tarsomere 1.24 mm long, 0.50 mm wide, moderately swollen. Length of second to fifth tarsomeres 0.64, 0.46, 0.32, 0.42 mm.

Abdominal tergites quite broad, clearly separated, in this respect similar to the recent species Bibio marci (L.).

Terminalia ( Fig. 18 ): gonostyli quite robust. Lobes of epandrium rounded, indentation between them broadly V-shaped.

Female (specimen B 47847), fig. 19: body and head black, femora reddish. Thorax length 3.7 mm. Fore tibia rather thick, black (only basal part visible). Wings as in male but larger (only basal half preserved). One large wing (BK 47961, Fig. 20 ) is presumably female. The basal and apical parts are not preserved, but the visible part is 9.1 mm long, longer than the entire wing of the male.

A partial specimen (BK 21) consists of most of the thorax, the basal part of both wings and the posterior margin of the head including the ocellar tubercle. It is certainly conspecific with the holotype but the gender is uncertain.

Remark: It is not possible to see a crossvein m-cu in the wings of the holotype male; this may be partly due to the somewhat rough structure of the matrix. Nothing suggests that the vein should be absent in this species and the female specimen figured has a clear m-cu. This vein is probably present in all Bibionidae , but is often inconspicuous in fossilized wings.

Figures

FIGURE 2 – 6. Bibio anatolicus sp. n., male. 2. head (MNHN B 47754). 3. hind femur and tibia (MNHN B 48011). 4. wing (MNHN B 47826). 5. terminalia, dorsal view (MNHN B 47890). 6. gonocoxosternite, ventral view (MNHN B 47826). Scale = 1 mm.

FIGURE 8 – 14. Bibio anatolicus sp. n., female. 8 head (MNHN BK 223). 9. antenna (MNHN B 47906). 10. fore tibia (MNHN BK 223). 11. hind leg (MNHN BK 223). 12. wing (MNHN B 47789). 13. terminalia, dorsal view (MNHN B 47789). 14. terminalia, lateral view (MNHN B 47906). Scale = 1 mm.

FIGURE 16 – 20. Bibio nigricosta sp. n., male. 16. hind leg (MNHN BK 450). 17. wing. (MNHN BK 450) Position of crossvein m-cu not possible to ascertain in this specimen. 18. terminalia, dorsal view (MNHN BK 450). 19. habitus (MNHN B 47847). 20. female (?), wing (MNHN B 47961). Scale = 1 mm