Prosoeca aquilo, Theron & Ellis & Midgley, 2025

Theron, Genevieve L., Ellis, Allan G. & Midgley, John M., 2025, A revision of a spring-active clade of Prosoeca Schiner, 1867 (Diptera, Nemestrinidae), keystone pollinators from the Greater Cape Floristic Region in South Africa, with descriptions of three new species, ZooKeys 1257, pp. 249-284 : 249-284

publication ID	https://doi.org/10.3897/zookeys.1257.155954
publication LSID	lsid:zoobank.org:pub:7D8BD25C-6BBF-44AE-8E5F-0B055043E470
DOI	https://doi.org/10.5281/zenodo.17485613
persistent identifier	https://treatment.plazi.org/id/4ED31217-87E4-5B1D-9E0C-B2DCEAFB305A
treatment provided by	ZooKeys by Pensoft
scientific name	Prosoeca aquilo
status	sp. nov.

Treatment

Prosoeca aquilo sp. nov.

Figs 1 View Figure 1 , 3 D View Figure 3 , 4 D View Figure 4 , 5 D View Figure 5 , 6 D View Figure 6 , 8 A, B View Figure 8

Type material.

Holotype: South Africa: • 1 ♂ Northern Cape: Kamieskroon: S. side Rooiberg Mts , high altitude fynbos, wetland stream; 30°26.276'S, 18°05.140'E; 1372 m; 23 Aug. / 2005; J. Coville & A. Roberts leg.; NMSA -DIP 79006 ; NMSA GoogleMaps . Paratypes: South Africa: • 2 ♂♂ Northern Cape: Kamieskroon: S. side Rooiberg Mts , high altitude fynbos, wetland stream; 30°26.276'S, 18°05.140'E; 1372 m; 23 Aug. 2005; J. Coville & A. Roberts leg.; NMSA -DIP 79002 , NMSA -DIP 79005 ; NMSA GoogleMaps . • 1 ♂ Northern Cape: Kamieskroon: S. side Rooiberg Mts , high altitude fynbos, wetland stream; 30°26.276'S, 18°05.140'E; 1372 m; 23 Aug. 2005; J. Colville & A. Roberts leg.; RMCA -ENT 000056700 ; RMCA GoogleMaps .

Diagnosis.

Relatively small species (length 11–12 mm) with a conspicuous grey border on the thorax and scutellum, abdomen black with posterior grey fascia interrupted by brown medial vitta, femora generally darker than tibiae and tarsi, proboscis length 0.8 ± 0.02 × the length of the body (range of un-extended proboscis length 8–10 mm), and wings with smoky brown infuscation on the anterior margin. Prosoeca aquilo sp. nov. can be distinguished from all others in the clade by the combination of its small size, the wings with smoky brown infuscation anteriorly and a paler posterior region and slight but distinct flexure on the anterior of the wing in males (Fig. 5 View Figure 5 ). Prosoeca aquilo sp. nov. differs from P. parva sp. nov. by having distinct infuscation on the anterior of the wing while P. parva sp. nov. has very little infuscation and wings are almost entirely hyaline (Fig. 5 D, F View Figure 5 ). Prosoeca ora sp. nov. has an abdominal pattern closely resembling that of P. aquilo sp. nov.; however, P. aquilo sp. nov. has grey pruinescence restricted to the posterior border of the tergites, not encircling the brown medial vitta, while P. ora sp. nov. has more extensive grey pruinescence medially (Fig. 3 D, E View Figure 3 ). Furthermore, the dense black pile laterally on the frons separates P. aquilo sp. nov. from P. ora sp. nov., which usually has white pile on these areas (Fig. 6 D, E View Figure 6 ). Prosoeca aquilo sp. nov. differs most notably from P. marinusi , P. peringueyi , and P. torquata by having a small body size and a proboscis shorter than the length of its body.

Description.

Male. Body length: mean 11.6 mm; range 11–12 mm ( n = 4). Intertegular width: mean 4.4 mm; range 4–5 mm ( n = 4). Proboscis length: mean 9 mm; range 8–10 mm ( n = 4). Wing length: mean 13.2 mm; range 12–14 mm ( n = 4).

Head. (Figs 4 D View Figure 4 , 6 D View Figure 6 ) Ground colour generally grey to black. Ocellar tubercle somewhat bulbous and developed, just evident above upper eye margin in profile, with dense silvery pruinescence; width between eyes at the anterior ocellus 3–3.5 × the length of the anterior ocellus; anterior ocellus separated from posterior ocelli by shallow transverse groove; pile generally long, black. Frons trapezoid; width anterior to ocellar tubercle 0.6 × the width above antennal insertions; slightly to moderately swollen between antennal insertions and anterior ocellus; swelling recedes strongly towards eye margin; pruinescence relatively dense, silver to brown; pile generally pale with black pile dorsolaterally, dense along lateral margins towards antennal insertions, but sparse medially. Antenna with scape 1–1.3 × length of pedicel; first flagellomere subequal to the length of scape + pedicel; style longer than scape + pedicel + flagellomere 1; ground colour dark brown to black, style darker than remainder of antenna; scape, pedicel and flagellomere 1 with irregular silver to brown pruinescence; pedicel with mostly elongate pile, black pile, flagellomere 1 with short black pile basally on the dorsal side. Facial area bulbous in profile, with horizontal groove present; with silver to brown pruinescence, evenly distributed across face; pile mostly white (sometimes with black pile interspersed), elongate, sparse, similar to that of frons. Gena with pile a mixture of black and white to pale yellow, elongate, and dense, forming the beard. Proboscis 0.7–0.9 × the length of the body, dorsal and ventral side black. Palpus with first segment significantly longer than that of second segment, second segment much narrower than first segment; colour generally dark brown to black; pile long on both segments.

Thorax (Fig. 3 D View Figure 3 ). Scutum dark grey to black; pruinescence mostly brown, with pale grey to silvery pruinescence complete along the lateral sides of the scutum, joining on scutellum; median and paired sublateral vittae absent; pile mostly black (sometimes with a few golden pile interspersed), sparse, shorter than the pile on the posterior of the scutellum; postalar callus with black pile dorsally, ventral side with a tuft of golden pile. Scutellum anterior margin covered by brown pruinescence; posterior margin with a dark, black border; pile on disc of scutellum black, relatively long, of similar density to that on the scutum; pile along posterior margin elongate, a mixture of black and pale, white or yellow, same density as on disc of scutellum; with some pale yellow to golden pile laterally. Pleuron mostly blackish; with silver pruinescence, sparser than on scutum; pile generally a mixture of black and white to yellow, relatively long, of intermediate density; most dense and elongate in two tufts, ventral and anterior to the base of the wing and between postalar callus and posterior spiracle; tuft of pile anterior to wing base directed posteriorly, mostly white to golden with some black pile; tuft of pile on katatergite directed posteriorly, black and golden; katepimeron with pile absent. Legs. Coxae dark brown to black; with pile mostly off-white to golden, elongate, dense. Trochanters mostly blackish, with some yellow-brown colouring; pile short, very sparse. Femora yellow-brown (sometimes very dark to black), with dark marking on dorsal side of the distal end present; pile mostly black, mixed long and short, dense, but with elongate pile dorsally on proximal 1 / 3 to 1 / 2; ventral pile typically longer, sparse; hind femur with short pile more evenly distributed than on fore and mid femora. Tibiae yellow-brown to dark brown; with dense, short, dark pile and sparse, elongate pile (short pile may appear more golden on hind tibia), most dense on hind tibia. Tarsi red-brown to dark brown, hind tarsi tend to be darker. Wings (Fig. 5 D View Figure 5 ). Shape relatively slender; broadest distal to termination of M 4 on posterior margin; alula broad; costal margin with slight but distinct anterior curved flexure; Sc termination on C aligned with termination of M 4 on posterior margin of wing; R 1 termination closer to R 2 + 3 than to Sc; termination of Sc and R 1 well separated; short appendix just beyond fork on R 4 + 5 always absent; cross vein between M 1 and M 2 absent; cross vein just beyond fork between R 4 and R 2 + 3 absent; R 1 slightly curved upward; R 4 deep bowing upward; R 5 deeply bowing upward; M 1 and M 2 slightly curved upward; cell cua open at margin; CuA and CuP well separated. Dark marking on R 1 positioned just basal to humeral cross vein; membrane with smoky brown infuscation; infuscated on anterior 1 / 2–1 / 3 of wing; posterior region of wing somewhat paler but never hyaline; isolated darker patches distinct in pale region; the distinction between brown infuscation and pale brown membrane clearly delineated. Tuft of pile on base of wing white. Haltere with pale brown to yellow stalk; bulb dark brown.

Abdomen (Fig. 3 D View Figure 3 ). Colour of abdomen generally black; T 2 with posterior margin stout and relatively broad; abdomen tapering abruptly after T 3. Tergites with silvery pruinescence; membrane between T 1 and T 2 with silvery to brown pruinescence; medial brown pruinescent vitta distinct, extending from the posterior margin of T 1 to terminalia, usually not covering the full length of each tergite; grey pruinescence surrounding brown medial vitta, on T 2 – T 5; posterior margin of T 2 – T 4 with contrasting pruinescent border. Pile on tergites mostly black, both long and short, of intermediate density; along anterior margins of T 2 white to pale yellow (with some dark pile medially), elongate, of intermediate density; posterolateral pile on T 2 – T 4 black, elongate, dense; T 5 with pile along lateral margins more evenly distributed than that of T 2 – T 4. Sternites typically paler than tergites; grey to black; pruinescence silvery, dense. Sternites with pile mostly white, mostly long, sparse; pile on S 4 – S 5 black; pile on membrane adjacent to lateral margins of S 2 – S 4 typically with profuse, decumbent, elongate, white pile.

Genitalia (Fig. 8 A, B View Figure 8 ). Hypandrium triangular in shape; broad, tapering gradually towards the apex; laterally convex; 1.7 × longer than basal width; with apex projecting only slightly past the top of the gonocoxites. Hypandrium vestiture long, sparse, on the apical 2 / 3. Gonocoxite apical 1 / 2 not parallel sided; gonocoxites widest in apical 1 / 3, narrowing apically; rounded apically. Gonocoxite vestiture on the lateral 2 / 3, of apical 2 / 3, long, laterally projecting. Gonostylus with parallel sides; and narrow apical region. Phallus near parallel sided; narrowing apically.

Female. Unknown

Geographical distribution.

Only known from a single locality in the Kamiesberg mountains near Leliefontein in the Northern Cape of South Africa (Fig. 1 View Figure 1 ).

Biology.

Found visiting yellow Oxalis in marshy wetland, high-altitude Fynbos. This species has only been recorded on the wing in late August but is likely to be on the wing through most of the spring season.

Etymology.

From the Latin aquilo = Roman god of the north winds; referring to its current known northerly distribution in the Kamiesberg. To be treated as a noun in apposition.