Dilophus pinguis ( Heer, 1849 ) Skartveit & Krizmanić, 2020

Skartveit, John & Krizmanić, Katarina, 2020, Revision of fossil Bibionidae (Insecta: Diptera) from the Miocene of Radoboj, Croatia, Zootaxa 4759 (3), pp. 351-378 : 367-369

Dilophus pinguis ( Heer, 1849) comb.n.

( Figs. 15–17 , 34–37 )

Bibio pinguis Heer, 1849: 220

Type material: Lectotype (female, hereby designated) ( SLJG 77473) this is the specimen depicted by Heer (1849: Plate XVI, Fig. 11a ). The specimen has been labeled as a syntype of Bibio maculatus Heer but this is obviously not correct. The specimen was described as Bibio pinguis radobojanus by Heer. Specimen SLJG 77475 is probably the counterpart of SLJG 77473. Paralectotype (female, hereby designated) ( NHMW 1842/0050/0022), this is the specimen described as « var. paulo minor » and depicted by Heer (1849: Plate XVI, Fig. 11c ) We have not seen the type of B. pinguis oeningensis ; according to the original description ( Heer 1849: 221 and Pl. XVI, Fig. 11b ) it would be quite similar to B. pinguis radobojanus .

Additional material. Male ( CNHM 1832).

By far the biggest Dilophus species, fossil or recent, known from Europe.

Description

Male (N=1 for all measurements): Total length 12.6 mm.

Head: Not preserved in the specimen at hand.

Thorax: Length 3.2 mm. Very poorly preserved, spine combs not possible to see.

Wing: Length 9.5 mm, width 3.3 mm. Dark brown fumose, anterior area a little darker than posterior. Vein measurements: basal R 3.6 mm, distal R 1 2.5 mm, basal R s 0.9 mm.

Legs: Fore leg relatively slender, tibia possibly with two small spines mesally, apical spines fine and short, not possible to count. Hind leg ( Fig. 34 ) femur 4.0 mm long, 0.75 mm wide, moderately clavate, tibia 4.1 mm long, 0.6 mm wide, straight-sided, first tarsomere slender.

Abdomen: Length 8.3 mm, width 2.1 mm, cylindrical and relatively slender.

Terminalia ( Fig. 35 ): Gonostylus digitiform as usual for genus. Shape of epandrium not possible to make out in the specimen at hand.

Female: Total length 15.0 mm

Head: Length 2.0 mm. Dark brown, presumably black in life. Complex eye small, rounded, protruding. Occiput approximately twice as long as complex eye. Ocellar tubercle low, not conspicuous. Antennal flagellum stout, possibly six-segmented.

Thorax: Length 5.6 mm. Ochreous-brown, pronotum probably a little darker. Spine rows on pronotum and mesonotum apparently consisting of short, stout spines.

Wing: Length 12.3 mm, width 4.4 mm. Apparently hyaline (no pigment preserved). Veins colourless. Basal part of R s about equal to R-M.

Legs: Femorae ochreous-brown, tibiae and tarsi blackish-brown. Spine arrangement on protibia unclear: possibly three mesal spines in an oblique row. Apical spine circlet with short, widely separated spines, possibly six. Hind tibia and tarsus slender. Length of fore tibia 3.1 mm, hind femur 4.4 mm, hind tibia 4.7 mm.

Abdomen: Length 10.1 mm. Ochreous-brown. Pile not apparent. Cerci short, somewhat pointed.

Figures

FIGURE 11. Bibio firmus, female, holotype, SLJG 77471.

FIGURE 15. Dilophus pinguis, male, CNHM 1832.

FIGURE 16. Dilophus pinguis, female, lectotype, SLJG 77473.

FIGURE 17. Dilophus pinguis, female, paralectotype, NHMW 1842/0050/0022.

FIGURES 32–35. 32. Bibio giganteus, female, holotype, wing, SLJG 77605. 33. Bibio giganteus, female, holotype, head and thorax, SLJG 77605. 34. Dilophus pinguis, male, hind leg, CNHM 1832. 35. Dilophus pinguis, male, hypopygium, CNHM 1832. Scale bar = 1 mm.

FIGURES 36–38. 36. Dilophus pinguis, female, lectotype, habitus, SLJG 77473. 37. Dilophus pinguis, female, lectotype, wing, SLJG 77473. 38. «Bibio ungeri», type, habitus with tentative wing venation, SLJG, no catalog number. Scale bar = 1 mm.