Dilophus malagasicus, 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 : 313-315

Dilophus malagasicus sp.n. ( Figs. 9–10 , 61–68 )

Dilophus?femoratus Meigen sensu Hardy, 1962:169 .

Etymology: the epithet is derived from Malagasy, an alternate name for Madagascar.

Holotype (male) MADAGASCAR, Atananarivo province , Manjakatompo, 23.iv. 1958, F. Keiser leg. Label data: ́MADAGASCAR Tan. / Manjakatompo / 23. IV. 58/ F.KEISER», ́ Dilophus femoratus Meigen / Det. 1961 D.E. Hardy », «Coll. NMB » (red label) and « Dilophus malagasicus sp.n. / HOLOTYPE ♁ / J.Skartveit des. 2022» (handwritten on pink label). ( NHMB) .

Paratype (male): MADAGASCAR, Diana Region , Montagne d’Ambre, 21.v. 1958, F. Keiser leg ( NHMB) .

Other material studied: MADAGASCAR, Alaotra-Mangoro Province , Perinet, 29.ix. 1958, F. Keiser leg. (1 ♀). Due to the large sexual dimorphism in Bibionidae and just three specimens from three different localities being available for study, the association between male and female here is somewhat tentative, hence the female specimen is not given type status.These three are the specimens studied by Hardy (1962).

Previous records (as D. femoratus Meigen ): Madagascar ( Hardy 1962).

Diagnosis:A medium-sized (about 4 mm) species.Antennal flagellum short and stout, 7–8-segmented. Pronotal spine row with 12 spines arranged in three groups. Wing hyaline in both sexes with posterior veins pigmented, pterostigma clearly visible. Male hypopygium rectangular, epandrium rectangular, apically slightly concave, gonostylus with distinctive ́beak» apically.

Description:

Male (fig. 9) (N=2). Body length 4.2 mm (N=1).

Head (fig. 62): Length 0.62–0.78 mm, width 0.70–0.82 mm. Black, shiny. Complex eye with sparse, short, pale intraocular setae, about as long as the diameter of one facet. Occiput with sparse, long, pale, proclinate setae. Ocellar tubercle rather low. Underside of head with sparse, rather long, pale pile. Rostrum not at all produced beyond margin of complex eye. Palp brownish-black, rather short, last segment rounded, with short, brown setae. Antenna brown, apical half of pedicel paler, cylindrical, flagellum 0.28 mm long, 0.07 mm wide (N=1), 7-segmented, segments with short, brown setae.

Thorax: Length 1.00– 1.05 mm, width 0.69–0.72 mm. Dark reddish-brown, shiny, humeri a little lighter brown. Pronotal spine comb with 10 slender, sharp spines arranged 3 + 4 + 3. Menonotal spine comb with 10 rather close-set, short, sharp spines. Mesonotum with rather abundant, long, yellowish dorsocentral setae, irregularly arranged anteriorly, uniserial posteriorly. Sides of mesonotum mostly bare, but vertical part with about 10 upturned, long setae and strong, reticulate microsculpture. Scutellum small, with a few short marginal setae. Pleura reddish-brown, notably paler than mesonotum, without setae, mostly shiny, but most posterior parts with coarse, reticulate microsculpture. Haltere with yellowish-brown stem, blackish-brown knob.

Legs: Uniformly reddish-brown, rather stout, clad with rather long, mostly pale pile (mostly as long as width of leg). Fore femur relatively slender. Fore tibia (fig. 63) cylindrical, mesally with four slender, straight, oblique, sharp spines arranged in an oblique row, apically with circlet of 8 sharp spines. Mid tibia without spinose setae. Hind femur slightly curved, strongly clavate, hind tibia slender. Tibial spurs rather short and fine. All tarsi slender. Measurements (N=2 unless otherwise stated): fore femur 0.55–0.67 mm long, 0.20 mm wide, fore tibia 0.58–0.72 mm long, 0.08–0.11 mm wide, first fore tarsomere 0.32–0.36 mm long, 0.05–0.07 mm wide, mid femur 0.62–0.68 mm long, mid tibia 0.62–0.77 mm long, hind femur 0.82–1.05 mm long, 0.17 mm wide, hind tibia 0.87–1.03 mm long, 0.11–0.12 mm wide, first hind tarsomere 0.34–0.38 mm long, 0.07–0.08 mm wide.

Wing (fig. 61): Length 3.1–3.6 mm, width 0.98–1.08 mm, length/width = 3.1–3.3. Hyaline, with rather coarse microtrichia throughout. Anterior veins light brown, posterior veins brownish-yellow, all clearly pigmented. Costa basally with about 15 long setulae (decreasing in length apicad), for most of the length with setulae about as long as vein diameter, extending to half-way between apices of R 4+5 and M 1. Humeral crossvein absent. Pterostigma light brown, distinctive, elongate. Costal cell brownish-yellow, contrasting against rest of membrane. Subcosta straight, mostly distinctive. Crossvein R-M 3–4 times as long as basal R s. R 4+5 slender, gently curved. M basally connected to CuA by a slender venule. Fork of M asymmetrical, M 1 diverging forward from M/M 2. Crossvein M-CuA rather indistinctive, meets M at furcation. Cubital veins rather short, straight, fork of CuA triangular. CuP indistinctive, does not extend to edge of wing.

Abdomen: Length 2.1 mm (N=1). Black, shiny, sparsely clad with brown pile.

Terminalia: Hypopygium (figs. 64–65) 0.30–0.33 mm wide, more or less rectangular. Gonostylus 0.15 mm long (N=1), relatively slender, straight, apically with s sharp ́beak». Epandrium rectangular, rather wide, apically a little concave. Ventral indentation of gonocoxosternite wide and shallow, V-shaped.

Female (fig. 10) (N=1): Body length 4.2 mm.

Head (fig. 67): Length 0.82 mm, width 0.53 mm. Dark reddish-brown (mahogany-coloured), shiny, with scattered, pale setae except on frons which is entirely bare. The area just above the antennal sockets paler coloured than the rest. In side view the head is about twice as long as complex eye. The head extends about one half eye diameter anterior of complex eye. Ocellar tubercle low. Complex eye rather flat, with sparse, short, pale intraocular setae. Palp dark brown, rather slender. Antenna robust, cylindrical, grayish-brown, flagellum 0.43 mm long, 0.08 mm wide, 8-segmented.

Thorax: Length 1.52 mm, width 0.77 mm. Reddish-yellow, shiny, spine combs and a mesal stripe brownish-black. Dark mesal stripe anteriorly hourglass-shaped, including both spine combs, considerably contracted between them and behind mesonotal comb. Mesonotum almost entirely bare, with a few, scattered dorsocentral setae and a few short, pale setae on sides. Pronotal spine row with 12 strong, sharp spines, arranged 3+6+3. Mesonotum spine row with 14 short, sharp spines. Pleurae with meron brownish-red, otherwise reddish-yellow, bare and shiny. Haltere with yellowish-brown stem, brown knob.

Legs: Robust, all segments with relatively long, pale pile. Coxae yellow, femorae yellow with reddish-brown tips. Fore tibia (fig. 68) brownish-black, mid- and hind tibiae reddish-brown, tarsi dark brownish. Fore tibia robust, expanding apicad, mesally with 4 strong, sharp spines on oblique row, apically with circlet of 8 strong, sharp spines. Measurements (N=1): fore femur 0.68 mm long, 0.27 mm wide, fore tibia 0.66 mm long, 0.13 mm wide, first fore tarsomere 0.50 mm long, 0.08 mm wide, mid femur 0.80 mm long, hind femur 1.22 mm long, 0.19 mm wide, hind tibia 1.20 mm long, 0.14 mm wide, first hind tarsomere 0.48 mm long, 0.08 mm wide.

Wing (fig. 66): Length 4.48 mm, width 1.52 mm, length/width = 2.94. Light brownish fumose, otherwise as in male.

Abdomen: Length 2.7 mm, width 0.6 mm. Cylindrical, yellowish-brown, shiny, with sparse, fine, pale pile.

Terminalia: Last sternite reddish-yellow. Cercus brownish-black, rounded.

Distribution and ecology: The available specimens are from forest habitats in Central and Northern Madagascar. The three known specimens have been collected at three widely scattered localities, at altitudes between 800– 1500m.

Flight period: The three available specimens have been collected in April, May and September, respectively ( Table 2 ).

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 61–65. Dilophus malagasicus sp.n. 61. Male, wing. 62. Male, head and thorax. 63. Male, fore tibia. 64. Male, terminalia, dorsal. 65. Male, terminalia, ventral.

FIGURES 66–68. Dilophus malagasicus sp.n. 66. Female, wing. 67. Female, head and thorax. 68. Female, fore tibia.