Dilophus paucidens Hardy, 1962

Skartveit, John & Freidberg, Amnon, 2023, Revision of the genus Dilophus Meigen, 1803 (Diptera, Bibionidae) from the Afrotropical Ecozone, Zootaxa 5360 (3), pp. 301-354 : 312-313

Dilophus paucidens Hardy, 1962 ( Figs. 8 , 56–60 )

Type locality: MADAGASCAR, Diana, Montagne d’Ambre. Holotype in Natal Museum, paratype in Univeristy of Hawaii collection.

Previous records: Madagascar ( Hardy 1962).

Material studied: MADAGASCAR, Fianarantsoa, Ranomafana National Park, Talatakely 800 m SW entrance, 21° 15.48’ S, 47°25.27’ E, 610 m., 16.–19. x. 2014, A.H. Kirk-Spriggs & R. Harin’Hata leg,. ( NMSA), 5 ♁♁ .

Diagnosis: a very small (body length 2.8–3.2 mm), shiny, entirely black species. Pile very inconspicuous, superficially the body appears to be quite naked. Protibia slender with three mesal spines. Wing hyaline, veins practically colourless, pterostigma invisible. Gonostylus straight with a distinctive “head”, apically a little pointed.

Male (fig. 8): Total length 2.8–3.2 mm (N=5), body entirely black, very shiny.

Head (fig. 57): Length 0.53–0.61 mm (N=5), width 0.64–0.68 mm (N=4). Black, shiny, underside with few, short, pale setae. Occiput with one row of strong but rather short, pale setae. Ocellar tubercle low, no seta eon tubercle but two pairs of strong, proclinate, brownish setae immediately behind it. Complex eye very sparsely clad with short, erect, intraocular pile, each hair about as long as the diameter of one eye facet. Lower portion of complex eye rather large. Antenna: robust, scapus light brown, rounded, a little wider than the more distal segments. Pedicellus nearly as long as wide, diameter like flagellum. Flagellum 0.25–0.28 mm long (N=5), about 0.05 mm wide, robust, seven-segmented, each segment more or less globular, densely clad with short, pale hairs. The terminal segment is rounded-conical. Palp conspicuosly short, four-segmented, the three basal segments slender, terminal segment rather large, oval with three strong setae. Rostrum not at all produced beyond complex eye margin.

Thorax: Length 0.81–0.90 mm (N=5), width 0.55–0.58 mm (N=5). Entirely black, smooth and very shiny. Area behind scutellum (metanotum) yellowish-brown. Anterior spine row with 8 strong spines. Posterior row with 10 spines, 6 of which form a mesal row, two pairs more posterior. Mesonotum nearly entirely bare, about six setae along notaulix. Between the two spine rows some (about 10 on each side) fine, pale setae laterally. Pleurae bare with fine, reticulate microsculpture, very shiny. Haltere black with lighter coloured stem, two small, dark setae on stem.

Legs: Coxae reddish-brown, bare with reticulate microsculpture. Femorae light reddish brown, apically darker, tibiae and tarsi dark reddish brown. Legs covered with rather sparse, relatively short, brownish setae. Fore femur relatively slender. Fore tibia (fig. 58) slender, cylindrical, mesally with three strong spines forming an oblique row and a fourth spine externally about one spine length more basad. Apical circlet of 8 rather long, sharp spines. Fore tarsus slender, first segment a little longer than second and third combined. Mid tibiae apically with strong, sharp spurs and some strong setae apically, but not with apical spine circlet. Hind femur somewhat clavate, apical fourth narrowing. Hind tibia slender, relatively short, curved, sharp spurs, sensillar field not conspicuous. Hind tarsus very slender, first segment a little longer than second and third combined. Measurements (N=5 unless otherwise stated): fore femur 0.49–0.58 mm long, 0.13–0.16 mm wide, fore tibia 0.51–0.57 mm long, 0.07–0.08 mm wide, first fore tarsomere 0.30–0.34 mm long, mid femur 0.47–0.55 mm long (N=4), mid tibia 0.53–0.58 mm long (N=4), hind femur 0.74–0.81 mm long, 0.11–0.13 mm wide, hind tibia 0.74–0.76 mm long, 0.08–0.09 mm wide, first hind tarsomere 0.28–0.33 mm long.

Wing (fig. 56): Length 2.40–2.63 mm, width 0.76–0.85 mm, length/width = 2.86–3.24 (all N=5). Hyaline, entire membrane with strong, brown microtrichia. Distal part of Costa and R-veins brown, inner part of Costa and posterior veins colourless. Humeral crossvein and pterostigma not visible. Costa with fine, brown setules, other wing veins bare. Subcosta straight, rather weak. R 1 may be faint distally (variable). Crossvein R-M about 2.5 times as long as basal R s. Basal section of M fine and straight. R 4+5 evenly curved, ends substantially before wing tip. Costa extends nearly half-way between apices of R 4+5 and M 1. M- and CuA-veins apically straight. Crossvein MCuA rather indistinctive, meets M at furcation. Fork of CuA wide, enclosing a broadly triangular area. CuP straight, weak and indistinctive. Apical and posterior margins with fringe of relatively long, pale setules.

Abdomen: Length 1.3–2.1 mm (measurements obviously affected by shrinking), width approx. 0.3 mm, slender, sparsely pilose, shiny. Sternites entirely shiny, tergites basally shiny, apically with strong, reticulate microsculpture.

Terminalia (figs. 59–60): Width of hypopygium 0.21–0.27 mm (N=4). Gonostylus 0.11–0.13 mm long (N=4), strong, with dense, strong setae, straight, apically curved and pointed. Epandrium rectangular, apically straight, very sparsely clad with short setae. Gonocoxosternite apically with V-shaped, wide and shallow excavation.

Female unknown.

Distribution and ecology: The species has been collected in Montagne d’Ambre national park in the extreme north of Madagascar and in Ranomfana national park in the southern part of the country. The locality are in forest at altitudes of 600–1400m.

Flight period: The available specimens have been collected in October.

Figures

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 56–60. Dilophus paucidens Hardy, 1962. 56. Male, wing. 57. Male, head and thorax. 58. Male, fore tibia. 59. Male, terminalia, dorsal. 60. Male, terminalia, ventral.