Dilophus baleensis, Skartveit & Freidberg, 2023

Skartveit, John & Freidberg, Amnon, 2023, Revision of the genus Dilophus Meigen, 1803 (Diptera, Bibionidae) from the Afrotropical Ecozone, Zootaxa 5360 (3), pp. 301-354 : 308-311

Dilophus baleensis sp.n. ( Figs. 4–5 , 40–47 )

Etymology: the species is named after the Bale Mountains, in which many of the specimens studied were found.

Holotype (male) ETHIOPIA, Bale Mts. , Bale 3200 m. Label data: ́ETHIOPIA, BALE / Bale Mountains / 10 km S Goba / 3200 m 31. i. 2000 / A. FREIDBERG / & I. YAROM» and « Dilophus baleensis sp.n. / HOLOTYPE ♁ / J.Skartveit des. 2022» (handwritten on pink label). ( TAU)

Paratypes: same data as holotype, 2 ♁♁ ( TAU) ; ETHIOPIA, Bale , Bale Mts, Robe 30 km W, 2900m, 3. ii. 2000, 1 ♁ ( TAU) ; Bale , Bale Mts, 12 km S Goba 3400m, 31. i. 2000, 4 ♁♁ ( TAU) .

Other material: ETHIOPIA, Bale , Bale Mts, 2900m, 3. ii. 2000, 1 ♀ ( TAU) ; Bale , Bale Mts, 12 km S Goba, 3400m, 31. i. 2000, 2 ♀♀ ( TAU) ; Shewa , Menagesha Forest 3050m, 11. x. 2005 1 ♁ 1 ♀ ( TAU) ; Wagira , Gara Mulata, C. Kristensen leg., 8 ♁♁ 15 ♀♀ ( NHMUK, barcodes 010922035-045, 010922058-070) ; Simien Mts. nr. Mindigabsa, 3000m, 17.xi. 1952, H. Scott leg, 1 ♁ ( NHMUK barcode 014427871) ; Simien Mts , Maï Datcha (E. of Arcuasié), 4025m., 5.xii. 1952, 1 ♁ ( NHMUK barcode 014427872) ; Kefa , Jimma 2700m, 11. ii. 2000, 1 ♁ ( TAU) ; Matoso, 35 km S Jimma, 2480m, 7°27’N 36°53’E, 19. iv. 2013, 2 ♁♁ 2 ♀♀; Ahmar Mts. , Zigita , 150 km W Harrar Rt 4, 9°16.4’N 41°08.5’E, 2320 m, 9.–12. xi. 2007, 2 ♁♁ ( TAU) ; Gonder , Gonder 2360m, Goha Hotel, 12°37’N 37°28’E, 1. x. 2005, 2 ♁♁ ( TAU) ; Welo , Lalibela 2470m, 8.x. 2005, 1 ♀ ( TAU) ; Entoto , 2860m, 9°05.509’E 38°45.414’ E, 24. iv. 2013, 1 ♀ ( TAU)

Diagnosis: A medium-sized (body length 3.3–5 mm) species, body all-black in both sexes. Antenna stout with 8–9 flagellomeres. Male wing hyaline with dark brown anterior veins and costa. Male gonostylus apically blunt. Female frons with long, erect setae, about half as long as eye diameter.

Male (fig. 4): Colour entirely black, shiny. Total length 3.4–4.9 mm (N=14).

Head (fig. 41): Length 0.75–1.01 mm (N=14), width 0.91–1.19 mm (N=7). Shiny black. Rostrum not at all protruding. Ocellar triangle relatively large but low. Upper part of complex eye with rather dense, short, light brownish intraocular pile, pile on lower part sparser and longer. Lower side with long, fine, light grayish pile. Antenna short and stout, slightly clavate, flagellum 0.25–0.34 mm long (N=13), 0.07–0.11 mm wide (N=15), with 8–9 strongly transverse flagellomeres. Palp short and stout, terminal segment cylindrical.

Thorax: Length 1.10–1.66 mm (N=16), width 0.70–1.08 mm (N=16). Entirely shiny black with fine, reticulate microsculpture. Pronotum with spine row of 10 strong, erect, sharp spines forming a continuous, transverse row, mesonotal spine row including 10 short spines forming a single, transverse row. Acrostichal area entirely bare. Dorsocentral setae fine, light brownish, forming an irregular double row on each side. Scutellum with a few short, pale marginal setules. Pronotum laterally with rather long, pale setae, pleurae sparsely pilose with long, pale setae. Area just above wing base with c. 25 long, pale, erect setae. Haltere with blackish-brown knob, brown stem.

Legs: Blackish-brown with relatively long, pale pile. Fore tibia (fig. 42) robust, mesally with 3–4 strong, relatively short spines forming an oblique row, apically with circlet of 8 strong, sharp spines. Fore tarsus long and slender. Mid femur moderately clavate, mid tibia slender without strong setae, 2 short, curved, brown spurs. Hind femur moderately clavate, hind tibia slender with two short, dark, curved spurs, tarsus slender. Measurements (N=16 unless otherwise stated): fore femur 0.58–0.79 mm long, 0.22–0.30 mm wide, fore tibia 0.68–0.92 mm long, 0.08–0.13 mm wide, first fore tarsomere 0.42–0.62 mm long (N=14), mid femur 0.66–0.91 mm long (N=15), mid tibia 0.70–0.92 mm long (N=15), hind femur 0.94–1.27 mm long (N=15), 0.15–0.23 mm wide (N=15), hind tibia 1.00– 1.36 mm long (N=15), 0.10–0.15 mm wide (N=15), first hind tarsomere 0.36–0.50 mm long (N=15).

Wing (fig. 40): Length 3.28–4.29 mm, width 1.07–1.47 mm, length/width = 2.73–3.07 (N=16). Hyaline, slightly brownish, costal cell slightly darkened. Microtrichia relatively strong throughout. R-veins dark brown, posterior veins yellowish, almost colourless. Pterostigma 0.58–0.66 mm long, 0.16–0.21 mm wide (N=7), dark brown and distinctive. Costa with fine, pale setulae extending to 0.4* distance between apices of R 4+5 and M 1, terminating some distance short of wing tip. Humeral vein absent. Subcosta yellow, not very prominent, running well separated from R. R 1 terminating at middle of pterostigma. Radial sector rather short, about 0.4* as long as R-M. R 4+5 almost entirely straight. Stem of M basally rather weak, connected to stem of CuA. Fork of M asymmetrical, M 2 running in same direction as stem of M, M 1 basally rather weak. M-CuA joins M well before fork. CuA basally colourless and rather faint, fork of CuA wide, CuA 1 with small kink at crossvein M-Cu, CuA 2 apically curved a little basad. CuP weak, not reaching wing margin, running well separated from CuA. A 1 fairly distinctive on basal part of axillary lobe, but not reaching wing margin. Fringe setules on posterior margin fine, short and pale.

Abdomen: Length 2.4–2.7 mm (N=5), black with short, sparse, grayish pile. Microsculpture dense and reticulate, surface semi-matt.

Terminalia:Hypopygium (figs. 43–44) 0.28–0.44 mm wide (N=15), outline rounded, Gonostylus robust, straight, slightly pointed apically without a distinctive ́head». Epandrium rather small, much narrower than hypopygium, trapezoidal, apically almost straight, sparsely clad with short, fine setae. Mesal indentation in gonocoxosternite rather wide and shallow, W-shaped.

Female (fig. 5):

Total length 3.2–4.2 mm (N=7).

Head (fig. 46): Length 0.66–0.92 mm, width 0.50–0.65 mm (N=8). Blackish-brown. Head extends less than half eye diameter in front of complex eye. Ocellar triangle low, not prominent. Complex eye rather flat, less than 0.5* length of head. Frons flat, with erect setae about one-half as long as eye diameter. Antenna short and stout, brown, flagellum with 7–8 very transverse flagellomeres, length 0.24–0.32 mm (N=5), width 0.08–0.10 mm (N=6). Palp short and robust.

Thorax: Length 1.30–1.74 mm, width 0.72–0.92 mm (N=8). Yellowish-red with pronotal spine row, hourglass-shaped mesal area on pronotum and dorsal (acrostichal) stripe on mesonotum brownish-black. Pile very sparse and short. Pronotum with spine row of 14 erect, sharp spines, mesonotal spine row including 10 short, blunt spines forming a single, transverse row. Haltere with brownish-black knob, brown stem.

Legs: All femorae brownish-yellow with brown tips, tibiae and tarsi brown. Protibia (fig. 47) mesally with 4 strong, prominent spines forming an oblique row, apically with circlet of 8 strong spines. Mid tibia mesally with a few enlarged setae. Hind femur clavate, hind tibia slender, all tarsi slender. Measurements (N=8 unless otherwise stated): fore femur 0.57–0.77 mm long, 0.25–0.35 mm wide, fore tibia 0.60–0.81 mm long, 0.09–0.13 mm wide, first fore tarsomere 0.38–0.51 mm long, mid femur 0.66–0.92 mm long, mid tibia 0.68–0.85 mm long, hind femur 0.98–1.30 mm long, 0.17–0.22 mm wide, hind tibia 1.02–1.40 mm long, 0.11–0.15 mm wide, first hind tarsomere 0.42–0.58 mm long.

Wing (fig. 45): Length 3.58–4.81 mm, width 1.32–1.66 mm, length/width = 2.64–2.91 (N=7), hyaline, very slightly yellowish. R-veins and stem of M light brown, posterior veins colourless. Pterostigma light brown. Venation as in male.

Abdomen: Length 1.7–2.7 mm, width 0.75–1.04 mm (N=5), dark olive-brown with sparse, short pile.

Terminalia: cerci oval, rounded, relatively large.

Distribution and ecology: The species is widely distributed in mountain areas of Ethiopia, known from mountain ranges throughout the country. It is a montane to alpine species which has been found at 2320–4025 meters altitude. The species has been collected from the marshy floor of a valley containing many Lobelia rhynchopetalum . Specimens from higher altitudes are generally larger, darker and somewhat hairier than specimens from lower altitudes, however in bibionids imago size often increases with altitude ( Skartveit & Solhøy 1997) and we interpret this as normal intraspecific, altitudinal variation.

Flight period: The available specimens have been collected between October and April.

Figures

FIGURES 1–4. 1. Dilophus nuptus(Speiser, 1914), male, habitus. 2. Dilophus nuptus (Speiser, 1914), female, habitus. 3. Dilophus vicarius (Hardy, 1948), male, habitus. 4. Dilophus baleensis sp.n., male, habitus.

FIGURES 5–10. 5. Dilophus baleensis sp.n., female, habitus. 6. Dilophus riftensis sp.n., male, habitus. 7. Dilophus riftensis sp.n., female, habitus. 8. Dilophus paucidens Hardy, 1962, male, habitus. 9. Dilophus malagasicus sp.n., male, habitus. 10. Dilophus malagasicus sp.n., female, habitus.

FIGURES 40–44. Dilophus baleensis sp.n. 40. Male, wing. 41. Male, head and thorax.42. Male, fore tibia. 43. Male, terminalia, dorsal. 44. Male, terminalia, ventral.

FIGURES 45–47. Dilophus baleensis sp.n. 45. Female, wing. 46. Female, head and thorax. 47. Female, fore tibia.