Dilophus erythraeus Bezzi, 1905

Skartveit, John & Freidberg, Amnon, 2023, Revision of the genus Dilophus Meigen, 1803 (Diptera, Bibionidae) from the Afrotropical Ecozone, Zootaxa 5360 (3), pp. 301-354 : 319-322

Dilophus erythraeus Bezzi, 1905 (figs. 15–16, 85–92)

Type locality: ERITREA, Adi Keyh (2500m) . Type in Museo Civico di Storia Naturale , Milan (not studied) Previous records: Yemen ( Hardy 1951a), Sudan ( Hardy 1951a), Eritrea ( Bezzi 1905), Kenya ( Hardy 1948, Hardy 1951a), Tanzania ( Hardy 1951a, Hardy 1960a), Uganda ( Hardy 1948, Hardy 1951a), Malawi ( Hardy 1951a), Democratic republic of Congo ( Hardy 1950, Hardy 1951a, Hardy 1952a, Hardy 1952b), Rwanda ( Hardy 1950, Hardy 1955), Burundi ( Hardy 1952c), Zimbabwe ( Hardy 1951a), Republic of South Africa ( Hardy 1951a)..

Material: YEMEN, Kaulat-el-Asabeir, N.E, of Haz , 16 mi. N.W. of San’a, 2870m, 4.ii. 1938, 1 ♁ ( NHMUK) , Usafira , 1 mile N. of Ta’izz, 1370m, 18.vii.1937, 1 ♀ ( NHMUK) , San’a, 2400m, 26.ii. 1938 ( NHMUK) . ETHIOPIA, Ahmar Mts., Kulubi , 10. xi. 2007, 1 ♁ ( TAU) , Ahmar Mts., Kersa , 9. xi. 2007, 1 ♀ ( TAU) , Gedamba , 25 km Addis Ababa, 2200m, 24. iv. 2013, 1 ♁ ( TAU) , Shewa, Wendo Genet , 2100m, 29. i. 2000, 1 ♁ ( TAU) , Shewa, Wendo Genet , 1900m, 28. i. 2000, 1 ♁ ( TAU) , Welo, Gondi 60 km SW Lalibela, 2485m, 9. x. 2005, 1 ♁ ( TAU) . KENYA, Kericho, 9. x. 1998, 1 ♁ ( TAU) , Kericho, 25. viii. 2003, 2 ♁♁ 3 ♀♀ ( TAU) , Kabarnet , 11.–12. x. 1998, 1 ♁ 1 ♀ ( TAU) , Bungoma, 10. x. 1998, 1 ♁ ( TAU) , Taita Hills, Mwatata-Wundanyi Rd 1000–1400m, 18. ix. 2005, 1 ♁ ( TAU) , Taita Hills, Mwanda 1800m, 19. ix. 2005, 1 ♀ ( TAU) , Taita Hills, Vuria Peak 2200m, 19. ix. 2005, 1 ♁ ( TAU) , Naivasha, Magura 2085m, 6. ii. 2011, 1 ♁ 3 ♀♀ ( TAU) , Naivasha , 14.–17. i. 1972, 1 ♀ ( TAU) , Nairobi, Karura Forest , 16. x. 2007, 1 ♁ ( TAU) , Nairobi, Muthaiga North , 1650m, 1. iv. 2013, 3 ♁♁ 3 ♀♀ ( TAU) , Nairobi, Muthaiga North , 1650m, 8. iv. 2013, 1 ♁ 4 ♀♀ ( TAU) , Nairobi , vii. 1969, C.F. Dewhurst leg., 18♁♁ ( NHMUK) , Nairobi , 9.18. vii.1970, A.E. Stubbs leg, 1 ♁ ( NHMUK) , Khalengwe, nr. Endebess , 1834m, 27. vii. 2013, 3 ♁♁ 1 ♀ ( TAU) , Equator. 30.x. 1983, 4 ♁♁ 1 ♀ ( TAU) , 10 km E. Kitale , 2. xi. 1983, 1 ♁ ( TAU) . Mt. Elgon , heath zone 3200– 3500m, ii. 1935, F.W.Edwards leg, 1♁ 2♀♀ ( NHMUK) , Molo, N. of Nakuru, 21.vii.1970, A.E. Stubbs leg., 1 ♁ ( NHMUK) , Kabete , vii.1916, R.H. Deakin leg., 1 ♀ ( NHMUK) , Nyeri, iii–iv.1948, M. Steele leg., 2♀♀ ( NHMUK) , Nanyuki (S.), v.1948, van Someren leg., 1 ♀ ( NHMUK) , « Kenya Colony », 13.i.1931, R.H. LePelley leg., 1♁ 5♀♀ ( NHMUK) . UGANDA, Kisoro 2000m, 26. xii. 1995, 1 ♁ ( TAU) , Mt. Muhavura 2350m, 29.xii.1995, 1 ♀ ( TAU) . TANZANIA, Njombe 10 km SE, 2000m, 27.–28.viii.1996, 1 ♀ ( TAU) , Njombe, 1830–1980m, 24.ii.1957, 1 ♀, 20.ix.1957, 2♀♀ ( NHMUK) , W. Usambara, Lushoto , 17.–18. viii. 2003, 1 ♁ 2 ♀♀ ( TAU) , Usambara Mts, nr. Lushoto , 1300m, 10.–15.ix.1992, 2 ♁♁ ( TAU) , Usambara Mts. , Rt B 124, 1500m, 9.ix.1992, 1 ♀ ( TAU) , New Langenburg , vi.1919, H.S. Stannus leg., 2 ♀♀ ( NHMUK) . BURUNDI, Kayanza, Kibira NP, Rwegura 2100m, 28– 30.i. 2011, 2 ♁♁ ( TAU) . MALAWI, Ntchisi Lodge , 1370m, 23. xii. 2009, 1 ♁ ( TAU) , Zomba Plateau, South Water Board Cottage , 1471m, 5. i. 2010, 1 ♀ ( TAU) , Limbe , ix. 1916, R.C. Wood leg., 1 ♁ 1 ♀ ( NHMUK) . ZIMBABWE: Mashonaland, Mt. Chirinda , 2680m, 12.vi.1911, C.F.M. Swynnerton leg., 102 ♁♁ 25 ♀♀ ( NHMUK) . REPUBLIC OF SOUTH AFRICA, Inn on Robber’s Pass 1400m, 27. xii. 1994, 1 ♁ ( TAU) , Johannesburg, Parktown North , i.–ii.1930, 1 ♀ ( NHMUK) . NAMIBIA, Grootfontein, Dakota 424, 13.–23. xii. 1993 ( NNM) . ANGOLA: Chianga , 21.–24.iii. 1972, 2 ♁♁ 1 ♀ ( NHMUK) . CAMEROON, Mezam, Sincoa vill. 6 ♁♁ ( NMSA). MNHN: material from Kenya and Cameroon. Previously recorded from present Democratic Republic of Congo , Eritrea , Kenya, Malawi, South Africa , Sudan , Tanzania , Uganda , Yemen and Zimbabwe (Hardy 1951) .

Diagnosis: A smallish (2.3–3.9 mm), compact species, body with very inconspicuous pile, appearing nearly naked. The species is most readily recognised by the costa ending immediately after the apex of R 4+5, in all other afrotropical species it extends to at least one-third the distance between apices of R 4+5 and M 1.

Male (fig. 15):

Total length 2.29–3.88 mm (N=16).

Head (fig. 86): Length 0.57–0.89 mm (N=15), width 0.75–0.98 mm (N=11). Complex eye nearly naked, intraocular setae about as long as one facet diameter, ocellar tubercle small, not prominent. Rostrum extending about one fourth diameter of lower complex eye. Occiput with very short, pale setae. Antenna cylindrical, flagellum 0.21–0.28 mm long (N=14), 0.06–0.09 mm wide (N=15), 7-segmented. Palp short.

Thorax: Length 0.92–1.38 mm, width 0.58–0.92 mm (N=16). Black, shiny, almost entirely without setae. Pronotal spine row with 8 sharp, erect spines. Mesonotal spine row with 12 short spines forming a semi-circle. Dorsocentral setae very short and inconspicuous. Haltere brownish-yellow.

Legs: Reddish-brown. Fore tibia (fig. 87) with 4 mesal spines in transverse (scarcely oblique) row, apically with circlet of 8 spines. Mid tibia with circlet of spine-like setae apically. Hind tibia sligthtly clavate, all tarsi slender. Measurements (N=16 unless otherwise stated): fore femur 0.49–0.68 mm long, 0.17–0.23 mm wide, fore tibia 0.55– 0.72 mm long, 0.08–0.12 mm wide, first fore tarsomere 0.34–0.47 mm long (N=13), mid femur 0.51–0.75 mm long (N=15), mid tibia 0.54–0.75 mm long, hind femur 0.79–1.11 mm long (N=15), 0.12–0.19 mm wide (N=15), hind tibia 0.85–1.19 mm long (N=15), 0.08–0.13 mm wide (N=14), first hind tarsomere 0.32–0.47 mm long (N=14).

Wing (fig. 85): Length 2.55–3.51 mm, width 0.87–1.19 mm, length/width = 2.46–3.28 (N=14), hyaline. Pterostigma invisible. R-veins and base of M yellowish, posterior veins colourless. Costa with sparse, fine setulae, terminates at apex of R 4+5. Humeral vein absent, subcosta nearly invisible. Basal Rs short, about 0.2* R-M. R 4+5 almost straight. Fork of M asymmetrical. M-CuA joins M a little before furcation. Fork of CuA moderately wide (less so than in previous species). Rather symmetrical since CuA 2 is distinctly curved apicad. No kink in CuA 1 at M-CuA, CuA 2 apically straight. CuP indistinctive, A 1 basally fairly distinctive. Fringe very inconspicuous.

Abdomen: black, laterally with erect setae, otherwise virtually bare.

Teminalia: Hypopygium (figs. 88–89) width 0.28–0.49 mm (N=14), trapezoidal and slightly rounded in outline. Gonostylus straight, with a distinctive ́head» and a slightly pointed tip. Epandrium wide, trapezoidal, apically gently concave, sparsely clad with fine setae.Ventral indentation of gonocoxosternite very shallow, about one-eighth of segment length.

Female (fig. 16):

Total length 3.2–3.8 mm (N=4).

Head (fig. 91): Length 0.75–0.83 mm, width 0.52–0.58 mm (N=4), dark brown, shiny. Head length approximately twice length of complex eye in lateral view. Ocellar tubercle rather small and low. Occiput with a few short, strong setae, frons with some backward-pointing setae. Antenna cylindrical, flagellum 0.30–0.34 mm long, 0.08–0.09 mm wide (N=4), 8-segmented. Head extends about one half eye diameter anterior to eye. Palp short, last segment conical. Underside with a few small, white setae.

Thorax: Length 1.36–1.66 mm, width 0.70–0.91 mm (N=4). Yellowish-red with brownish-black dorsal stripe. Pleurae mostly reddish-brown, meron bicoloured: dorsally yellowish-red, ventrally brown. Almost entirely naked. Pronotal spine row with 9–12 erect, sharp spines, mesontal spine row with 11–12 short spines placed on a raised ridge. Haltere yellowish-brown.

Legs: Fore coxa reddish-yellow, mid- and hind coxae reddish-brown. Femorae reddish-yellow, apical fourth brown. Tibiae and tarsi blackish-brown. Fore tibia (fig. 92) mesally with 4 sharp spines on oblique row, apically with circlet of 8 strong spines. Mid tibia anterioventrally with row of strong, spinelike setae. All tarsi slender. Measurements (N=4 unless otherwise stated): fore femur 0.62–0.70 mm long, 0.26–0.30 mm wide, fore tibia 0.72– 0.75 mm long, 0.11–0.12 mm wide, first fore tarsomere 0.43–0.49 mm long (N=3), mid femur 0.68–0.79 mm long, mid tibia 0.70–0.79 mm long, hind femur 0.98–1.15 mm long, 0.20–0.21 mm wide, hind tibia 1.08–1.26 mm long, 0.13 mm wide, first hind tarsomere 0.45–0.57 mm long.

Wing (fig. 90): Length 3.62–4.10 mm, width 1.17–1.42 mm, length/width = 2.78–3.09. Colour and venation as in male.

Abdomen: entirely blackish-brown. Cerci rounded.

Distribution and ecology:This is the most widely distributed of the afrotropical Dilophus and ranges from Yemen south to the northern part of the Republic of South Africa, to the west at least to Cameroon.The species has been recorded at altitudes between 1000–3500m and appears to be quite eurytopical, though the majority of the localities are montane. The species has been collected from cultivated fields and from the heath zone of mountains.

Flight period: the available specimens have been collected between late July and April, suggesting that adults can be found almost throughout the year, not surprisingly for a species so widespread in tropical areas ( Table 2 ).