Dilophus capensis Edwards, 1925

Skartveit, John & Freidberg, Amnon, 2023, Revision of the genus Dilophus Meigen, 1803 (Diptera, Bibionidae) from the Afrotropical Ecozone, Zootaxa 5360 (3), pp. 301-354 : 317-318

Dilophus capensis Edwards, 1925 (figs. 13–14, 77–84)

Type locality: Type in NHMUK.

Material: Syntypes, 2♁♁ 1 ♀ REPUBLIC OF SOUTH AFRICA, Cape Town.. Label data ́ Cape Town/ On bones of whale skeleton oozing with oil» (handwritten), ́Brit.Mus./ 1922 33.3.» (handwritten), ́Cotype Dilophus capensis Edw. » (circular, green-edged label), ́ Syntype » (circular, blue-edged label), ́ SYNTYPE / Dilophus / capensis/ Edwards / det. J.E. Chainey, 1995», ́BMNH (E) #/ 252975», and ́NHMUK 014427896 (with barcode) ».

Previous records: Republic of South Africa (Edwards 1925, Hardy 1951a, Hardy 1960b)

Other material: REPUBLIC OF SOUTH AFRICA, W. Cape, West Coast NP 2 ♁♁ 1 ♀ ( NMSA) . W. Cape, Table Mountain NP, Rivermine 6 ♁♁ 6 ♀♀ ( NMSA) . W. Cape, Ceres Bergfynbos Res. 1 ♁ ( NMSA) , W. Cape, Huguenot Tunnel 1000m, 30. viii. 2003, 5 ♁♁ ( TAU) . S. Cape Prov., Katberg 1200m, x. 1922, 1 ♀ ( NHMUK) , Natal, Ulundi , 1525–1980m, ix.1896, G.A,K. Marshall leg., 1 ♀ ( NHMUK) .

Diagnosis: A medium-sized (3.5–5 mm) species, body with quite indistinctive pile, appearing nearly naked. Mouthparts elongate, extended. Flagellum cylindrical, 8-segmented. The species is most easily recognised by the protibial spines being very small, much smaller than in other afrotropical species. Male hypopygium trapezoidal, gonostylus quite short, slightly curved.

Male (fig. 13)

Total length 3.6–4.9 mm (N=6).

Head (fig. 78): Length 0.92–1.09 mm (N=7), width 0.85–0.97 mm (N=5). Large. Complex eye with very short, brown intraocular pile. Ocellar tubercle small but fairly prominent. Rostrum slightly produced, extending as long as diameter of lower complex eye anterior to complex eye. Antenna cylindrical, flagellum 0.25–0.35 mm long, 0.06– 0.08 mm wide (N=7), 8-segmented, flagellomeres moderately transverse. Venter with long, pale setae. Occiput with long, procumbent, pale setae.

Thorax: Length 1.17–1.42 mm, width 0.70–0.85 mm (N=6). Black, shiny. Pronotal spine row with 10 short spines, mesonotal row with 10 spines forming continuous arch. Acrostichal area bare, dorsocentral setae sparse and irregular, scutellum with short, procumbent marginal setae. Pleurae nearly naked. Haltere black.

Legs: brownish-black. Protibia (fig. 79) rather slender, cylindrical, with 4 small mesal spines forming slightly oblique row, apical circlet of 8 small spines.All tibiae ventrally with 6–8 long, whitish setae. Hind femur moderately clavate, ventrally with long, pale setae. Tibiae and tarsi slender. Measurements (N=7 unless otherwise stated): fore femur 0.58–0.75 mm long, 0.19–0.24 mm wide, fore tibia 0.62–0.79 mm long, 0.07–0.10 mm wide, first fore tarsomere 0.42–0.50 mm long, mid femur 0.64–0.77 mm long (N=6), mid tibia 0.68–0.83 mm long (N=6), hind femur 0.87–1.13 mm long, 0.15–0.19 mm wide, hind tibia 1.02–1.19 mm long, 0.10–0.13 mm wide, first hind tarsomere 0.38–0.45 mm long.

Wing (fig. 77): Length 2.95–3.73 mm, width 1.01–1.23 mm, length/width = 2.59–3.04 (N=7). Hyaline with very fine microtrichia. Pterostigma large, brown, distinctive. R-veins and stem of M dark brown, posterior veins colourless. Costa with very short setulae, extending to 0.4* distance between apices of R 4+5 and M 1. Humeral vein absent. Subcosta colourless, quite indistinctive. R 1 terminates at middle of pterostigma. Basal Rs about 0.25* R-M. R 4+5 gently curved. M basally fairly strong, connected to base of CuA. Fork of M asymmetrical. M-Cu meets M at furcation. Fork of CuA wide, no kink in CuA 1 at M-Cu. CuA 2 apically straight. CuP and A 1 very indistinctive.

Abdomen: black, markedly conical. Relatively densely clad with fine, pale setae.

Terminalia: Hypopygium (fig. 80–81) 0.30–0.40 mm wide (N=7), trapezoidal in outline. Gonostylus 0.13–0.19 mm long (N=7), short and stout, curved, apically slightly pointed. Epandrium rectangular, apically distinctively concave. Terminalia without long setae, only short hairs present.

Female (fig. 14)

Total length 3.4–4.2 mm (N=4).

Head (fig. 83): Length 0.83–1.08 mm (N=4), width 0.53–0.57 mm (N=3). Black, shiny. Ocellar tubercle small, moderately prominent. Frons with numerous, short setae. Hind margin of complex eye about one eye diameter from occiput. Rostrum considerably produced. Complex eye quite protruding. Antenna cylindrical, flagellum 0.27–0.34 mm long, 0.08–0.09 mm wide (N=4), 8-segmented. Palp quite small.

Thorax: Length 1.32–1.55 mm, width 0.57–0.79 mm (N=4). Brownish-black, pronotum laterally brownish-red, shiny. Pronotal spine row with 10 quite short, sharp spines, mesonotal spine row with 12 short spines forming a continuous arch. Scutellum without marginal setae. Haltere dark brown.

Legs: Coxae brownish-red, femorae brownish-yellow with dark brown tips, tibiae and tarsi dark reddish-brown. Fore tibia (fig. 84) mesally with 4 short spines on oblique row, apically with circlet of 8 short spines. Mid- and hind tibiae with relatively strong setae but none conspicuously stronger than the others. Tibiae and tarsi slender. Measurements (N=4 unless otherwise stated): fore femur 0.58–0.62 mm long, 0.28–0.32 mm wide, fore tibia 0.62– 0.75 mm long, 0.09–0.12 mm wide, first fore tarsomere 0.42–0.57 mm long, mid femur 0.67–0.79 mm long, mid tibia 0.71–0.80 mm long (N=3), hind femur 1.06–1.13 mm long (N=3), 0.19–0.23 mm wide (N=3), hind tibia 1.13–1.26 mm long (N=3), 0.10–0.16 mm wide (N=3), first hind tarsomere 0.45–0.47 mm long (N=3).

Wing (fig. 82): Length 3.36–3.88 mm, width 1.06–1.36 mm, length/width = 2.87–3.43 (N=4). Light brown fumose, pterostigma brown, distinctive. R-veins and stem of M brown, posterior veins light brownish. Subcosta light brown. Venation as in male.

Abdomen: Dark reddish brown, shiny. Last sternite dark brown. Cerci small, rounded.

Distribution and ecology: The species is apparently endemic to the south coast of South Africa. It is the only Afrotropical Dilophus which has been recorded at sea level (the syntypes being associated with ́whale bones» strongly suggest a beach locality), but has also been recorded up to above 1500m in coastal monutains.

Flight period: The species has been recorded in August–October, that is, in spring ( Fig. 2 ).

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.