Afroxanthandrus longipilus Kassebeer, 2000

Midgley, John M., Goergen, Georg & Jordaens, Kurt, 2024, A revision of the Afrotropical hover fly genus Afroxanthandrus Kassebeer, 2000 (Diptera, Syrphidae), with the description of two new species and one new synonymy, European Journal of Taxonomy 968, pp. 60-85 : 78-80

Afroxanthandrus longipilus Kassebeer, 2000 stat. rev.

Figs 1 , 6 , 11 , 17 , 24

Diagnosis

Differs from A. comorosensis sp. nov. and A. conopeum sp. nov. in the curved posterior margin to the yellow fascia on tergite 2 (straight in A. comorosensis and A. conopeum ) and from A. congensis in the broad but thin fascia on tergite 3 (narrower and thicker in A. congensis ).

Type material examined

Holotype

DEMOCRATIC REPUBLIC OF THE CONGO • ♀; South Kivu Province, Kapanga; 1952; Froidebise leg.; RMCA, RMCA ENT 000016800 .

Paratype

DEMOCRATIC REPUBLIC OF THE CONGO • 1 ♀; Maniema Province, Nyangwe; Apr.–May 1918; R. Mayné leg.; RMCA, RMCA ENT 000056901 .

Other material examined

REPUBLIC OF THE CONGO • 1 ♀; Sangha Department, Nouabalé-Ndoki National Park, Mbeli camp ; 2°14′23.8″ N, 16°23′52.1″ E; elev. 372 m; 14–20 Feb. 2023; N.M. Bakala, V. Derozier, A. Kirk-Spriggs and G. László leg.; carrion bait; ANHRT 2023.3; RMCA DNA 1587B07; GenBank: PP828578 ; ANHRT, ANHRTUK 00282356 .

Description

MEASUREMENTS. Body: 9.1–10.3 mm; wing: 7.3–9.0 mm.

Female

HEAD ( Fig. 6 ). Black, with medium sized facial tubercle and a medium sized antennal prominence and medium sized frontal protuberance. Face straight in profile with a medium sized facial tubercle; widest just below the antennae, approximately 44% of the maximum head width, slightly narrowed ventrally, narrowest in line with dorsal oral margin, approximately 38% of maximum head width; covered with dense, yellowish-white pollinosity, completely obscuring the black ground colour, thinner pollinosity on the oral margin, gena and above the facial tubercle, facial tubercle bare; with medium length, light yellowish pilosity, medial region bare from oral margin to antennal base. Frons with yellowish-white pollinosity on the lower half, dense laterally but thinner medially, reaching from the frontal protuberance to the antennal prominence, the division between the pollinose and bare area forming a straight to slightly concave line. The antennal prominence and lunule are bare, the lunule orange in ground colour while the prominence is dark brown to black. Frons with medium length light yellow pilosity, sparse on lunule and antennal tubercle. Ocellar triangle acutely angled, clearly raised, anterior ocellus oval, about 0.6 times as long as wide, posterior ocelli oval, about 1.4 times as long as wide; with yellowish pilosity, short anteriorly but longer posteriorly. Occiput with pale brown to dark yellow pilosity dorsally, white laterally, thin dorsally but broad and scale like laterally; with pale yellow white pollinosity. Eyes bare, kidney-shaped in lateral view. Ommatidia equal sized across the eye. Antennae orange-brown; elongate, about as long as the maximum width of the face, narrow, parallel sided in lateral view, on dorsal side pedicel about as long as scape, postpedicel 2.5 times the length of the pedicel. Scape and pedicel with short thick dark brown pilosity, pedicel and postpedicel with sparse pollinosity, postpedicel without pilosity. Arista bare, inserted basally, about 1.2 times the length of the postpedicel.

THORAX ( Fig. 11 ). Scutum evenly rounded, except for a small raised oval bump on each side, anterior to the suture; black, postpronotum and postalar callus brownish, postalar callus with fine golden brown pilosity. Pilosity short dorsomedially, longer laterally, light brown, each pilis on a small, rounded, raised, base, which is not covered in pollinosity. Scutal pollinosity densest between the suture and postpronotum, along the suture, posterior to the suture and in an indistinct strip in front of the scutellum, light yellow-brown. Less dense on the remainder of the scutum. Scutellum very broad and large, ~60% the width and ~35% the length of the scutum; dark brown to black; pilosity denser than on the scutum, the density of the raised bases making the surface rough and the margin appear serrated; base narrowly bare (somewhat obscured by scutal pile), smooth; with a long, multi-rowed, light subscutellar fringe. Pleura dark brown to black; evenly rounded except for a moderate bulge on the posterolateral anepisternum; yellow to white pollinose, approximately even across pleura; pilosity yellowish white, bases smaller than on scutum. Dense pilosity limited to patches on the posterior anepisternum, anepimeron, katepisternum, and katatergite, scattered pilosity on the katepimeron. Metasternum bare. Plumule orangish yellow.

LEGS. Hind coxa with a small tuft of pile at posteromedian angle, with long, yellow-white pile on anterior surfaces; mid coxa with long pile on anterior surfaces; fore coxa with shorter, yellow pile on posterior distal margins. Trochanters with long yellow-white pile. Fore and mid femur orange brown with small yellow-orange sections at the base and apex, hind femur orange brown, with yellow basal section and more orange venterodistal section, fore femur slightly curved and thicker medially, mid femur with a slight medial swelling, hind femur swollen in distal two thirds. Fore and mid femur with medium length yellow pile, hind femur mostly covered with medium to long white pile, but with some dark pile in distal ⅓. Fore tibia completely white on posterior surface, white in basal ½ of anterior surface, brown in distal ½; mid tibia ranges from completely white in the holotype to white in basal ½, brown in distal ½; hind tibia brown. Pale sections of tibiae with short to medium yellow white pile, dark sections with short dark brown pile. Fore tarsus dark brown dorsally but paler brown ventrally. Mid basitarsus white in holotype, yellow in paratype and brown in ANHRTUK00282356, distal segments brown in all specimens, slightly darker dorsally. Hind tarsus brown dorsally, orange brown ventrally. All tarsi with brown pile, somewhat darker dorsally than ventrally.

WINGS. Extensively microtrichose in apical part, bare patches at base of c, r1, discal medial, cup cells. Alula evenly microtrichose. Cell bm extensively bare, but with a small dense patch of microtrichia in the distal region, in line with the knot of the spurious vein. Basal radial cell mostly bare, but with some microtrichia anterior to the knot of the spurious vein. Cell cua extensively bare, with some microtrichia centrally. Calypters yellow, darker dorsally, with fringe of long yellowish pile. Halteres yellow.

ABDOMEN ( Fig. 17 ). Elongate, broadly oval, though tergite 3 parallel sided. Slightly shorter than the wings, about as wide as the thorax, basic colour dark brown with dull, orange yellow markings. Tergite 1 orange yellow, slightly darker in a thin band at medial posterior boundary; tergite 2 light basally, extending medially to form a large medial marking with straight posterolateral sides, making the marking triangular in shape. Lateral margins of tergite 2 thinly yellow, joining with the main yellow marking anteriorly. Tergite 3 anterior with a narrow anteromedial band, about ⅓ of the length of tergite 3, almost reaching the borders of the tergite laterally and extending slightly posteriorly. Tergite 2 slightly longer than tergite 3, tergite 3 and tergite 4 of the same length and tergite 5 about ½ the length of tergite 4. Pile short centrally, longer laterally, golden brown, somewhat longer and paler lateral to tergite 1 and basolateral to tergite 2. Lateral fringe of pile Sternites light yellowish brown, slightly darker posteriorly, pile medium to long, yellowish.

Male

Unknown.

Distribution

Known from the Democratic Republic of the Congo (Kivu: Kapanga and Nyangwe) and the Republic of the Congo.

Remarks

Despite being from neighbouring countries, the known localities for A. longipilus are spread over ~ 1500 km, suggesting that the species is widespread but uncommonly encountered. All known localities are in Guineo-Congolian forests.

Figures

Fig. 1. Map of the known distribution of species of Afroxanthandrus Kassebeer, 2000 in the Afrotropical region.

Figs 2–6. Frontal view of the head of species of Afroxanthandrus Kassebeer, 2000. 2. A. comorosensis sp. nov., holotype, ♂ (RMCA ENT 000056900). 3. A. congensis (Curran, 1938), ♂ (ANHRTUK 00282353). 4. A. conopeum sp. nov., holotype, ♂ (NMSA-Dip 219971). 5. A. congensis, ♀ (ANHRTUK 00282352). 6. A. longipilus Kassebeer, 2000, ♀ (ANHRTUK 00282356). Scale bars = 1 mm.

Figs 11–12. Lateral view and wing of species of Afroxanthandrus Kassebeer, 2000. 11. A. longipilus Kassebeer, 2000, ♀ (ANHRTUK 00282356), lateral view. 12. A. congensis (Curran, 1938), ♂ (ANHRTUK 00282353), wing. Scale bars = 1 mm.

Figs 13–17. Dorsal view of the abdomen of species of Afroxanthandrus Kassebeer, 2000. 13. A. comorosensis sp. nov., holotype, ♂ (RMCA ENT 000056900). 14. A. congensis (Curran, 1938), ♂ (ANHRTUK 00282353).15. A. conopeumsp. nov., holotype, ♂ (NMSA-Dip 219971). 16. A. congensis, ♀ (ANHRTUK 00282352). 17. A. longipilus Kassebeer, 2000, ♀ (ANHRTUK 00282356). Scale bars = 1 mm.

Fig. 24. Neighbour-Joining tree generated from DNA barcode data for four species of Afroxanthandrus Kassebeer, 2000.