Prosoeca marinusi Barraclough, 2018

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.17488906
persistent identifier	https://treatment.plazi.org/id/10246222-AE72-5551-832D-9E14D669CBB9
treatment provided by	ZooKeys by Pensoft
scientific name	Prosoeca marinusi Barraclough, 2018
status

Treatment

Figs 1 View Figure 1 , 2 A View Figure 2 , 3 B View Figure 3 , 4 B View Figure 4 , 5 B View Figure 5 , 6 B View Figure 6 , 7 C, D View Figure 7

Prosoeca marinusi Barraclough, 2018: 412.

Type material examined.

Holotype: South Africa: • 1 ♂ Northern Cape: Nieuwoudtville Reserve; 3119 AC; 5 Aug. 1988; K. Steiner leg.; 2139; Host Plants, Lapeirousia oreogena ; Time: 1030–1200; SAM-DIP A 012376 ; SAMC . Paratypes: South Africa: • 3 ♂♂ 1 ♀ Northern Cape: Nieuwoudtville Reserve; 3119 AC; 5 Aug. 1988; K. Steiner leg.; Host plant Lapeirousia oreogena ; Time 1030–1200; 2146, 2147, 2141, 2144; SAM-DIP A 012376 ; SAMC . • 1 ♂ Northern Cape: Glen Lyon; 3119 NC; 26 Aug. 1990; K. Steiner leg.; 2664; Nemesia cheiranthus ; SAM-DIP A 012379 ; SAMC . • 1 ♀ Northern Cape: Nieuwoudtville Flower Res. ; 3119 AC; 20 Aug. 1986; K. Steiner; 1366; Lapeirousia oreogena 1602; SAM-DIP A 012378 ; SAMC . • 2 ♀♀ Northern Cape, Nieuwoudtville Flower Res. ; 3119 AC; 19 Aug. 1986; K. Steiner leg.; 1364 Lapeirousia oreogena 1408, 1365 Lapeirousia oreogena 1430; SAM-DIP A 012377 ; SAMC . • 3 ♂♂ 1 ♀ Northern Cape: Nieuwoudtville Reserve , 3119 AC; 5 Aug. 1988; K. Steiner leg.; 2140, 2145, 2142, 2138; SAM-DIP A 01 S 2376 ; SAMC . • 3 ♂♂ Northern Cape: Nieuwoudtville: Farm Melkbosfontein ; 31°21.12'S, 19°10.22'E; elev. 756 m; Lapeirousia oreogena ; Melin A, Colville JF, Krenn H & Karolyl F leg.; 23–25 Aug. 2014; 2143, 2136, 2137; SAM-DIP A 012376 ; SAMC GoogleMaps . • 1 ♂ Northern Cape: Nieuwoudtville Flower Reserve ; 2 Aug. 1984; K. Steiner leg.; SAM-DIP A 012384 ; SAMC .

Other material examined.

South Africa: • 1 ♂ 2 ♀♀ Northern Cape Province: Nieuwoudtville: Farm Melkbosfontein ; 31°21.12'S, 19°10.22'E; elev. 756 m; Lapeirousia oreogena ; Melin A, Colville JF, Krenn H & Karolyl F leg.; 23–25 Aug. 2014; SAM-DIP A 015475 , SAM-DIP A 015476 , SAM-DIP A 015488 ; SAMC GoogleMaps . • 1 ♀ Northern Cape: Nieuwoudtville: Hantamsberg Nat Botanical Garden; 735 m Spider Trail area ; 31°23.51'S, 19°08.24'E; J & A Londt leg.; 11 Sep. 2012; NMSA -DIP 205675 ; NMSA GoogleMaps . • 1 ♂ Northern Cape: Nieuwoudtville: Hantamsberg Nat Botanical Garden ; Rocky ridge; 31°23.51'S, 19°08.24'E; J & A Londt leg.; 11 Sep 2012; NMSA -DIP 205673 ; NMSA GoogleMaps . • 1 ♂ 1 ♀ Northern Cape: Nieuwoudtville: Hantamsberg Botanical Garden ; 31.39815°S, 19.14107°E; Steven Johnson leg.; 25–28 Aug 2019; NMSA -DIP 219352 , NMSA -DIP 219353 ; NMSA GoogleMaps . • 2 ♂♂ Northern Cape: Calvinia: Hantamsberg ; 3 Sep. 1994; 31; NMSA -DIP 079030 , NMSA -DIP 52483 [handwriting of Dr. J. Manning]; NMSA . • 1 ♂ Northern Cape: Calvinia: Hantamsberg ; 3 Nov. 1994; J. Manning leg.; NMSA -DIP 52484 ; NMSA . • 1 ♀ Northern Cape: 5 km N Nieuwoudtville ; 3119 AC; 5 Sep. 1981; J. Londt, L. Schoeman and B. Stuckenberg leg.; W. Mountain Karoo; NMSA -DIP 42755 ; NMSA . • 1 ♂ Northern Cape: Nieuwoudtville ; 23 Aug. 1993; on Lapeirousia oreogena ; 2; NMSA -DIP 51662 ; NMSA . • 1 ♂ Northern Cape, Nieuwoudtville ; 23 Aug. 1993; on Lapeirousia oreogena , 3, NMSA -DIP 76674 ; NMSA . • 1 ♀ Northern Cape: Nieuwoudtville ; 32; 4 Sep. 1994; on Lapeirousia oreogena ; NMSA -DIP 52474 [handwriting of Dr. J. Manning]; NMSA . • 1 ♀ Northern Cape: Nieuwoudtville Dist.: Oorlogskloof ; Sep. 1992; J. Manning leg.; on Lapeirousia jacquinii ; NMSA -DIP 54391 ; NMSA . • 1 ♀ Northern Cape: 13.5 km N Nieuwoudtville ; 31.16°S, 19.08°E; 18 Sep. 2007; C. Eardley leg.; SANC GoogleMaps .

Diagnosis.

Large-sized (length 14–22 mm), grey body with paler medial and paired sub-lateral vittae on the thorax and darker medial vitta present on the abdomen, scutellum with black posterior border, legs dark brown, proboscis length 2.19 ± 0.05 × the length of the body (range of un-extended proboscis length 31 – 46 mm), wings with smoky brown infuscation on the anterior 2 / 3 with no hyaline section of the wing. Prosoeca marinusi , P. torquata , and P. peringueyi can be distinguished from all other species in the clade by their proboscis which is longer than the length of their bodies, in contrast to P. ora sp. nov., P. aquilo sp. nov., and P. parva sp. nov. that have a proboscis shorter than the length of their body. Prosoeca marinusi has a distinctly darker posterior section of the wing that is never hyaline, compared to all other species in the clade (Fig. 5 B View Figure 5 ). Prosoeca marinusi differs from P. peringueyi and P. torquata , the other long-proboscid species in the clade, by having only a medial vitta on the abdomen (Fig. 3 B View Figure 3 ), with the sublateral patterning present in P. peringueyi (Fig. 3 C View Figure 3 ) and absent in P. torquata (Fig. 3 A View Figure 3 ). The hypandrium of P. marinusi is substantially broader basally than that of P. peringueyi or P. torquata . Prosoeca marinusi is a narrow endemic occurring in the Nieuwoudtville and Calvinia areas.

Some individuals may appear very dark, particularly on the abdomen, while others have a more subtle grey colouration. This dark colouration can largely be attributed to an abundance of dark pile that is less profuse and mixed with pale pile in paler individuals.

Redescription.

Male. Body length: mean 18 mm; range 14–22 mm ( n = 19). Intertegular width: mean 7.3 mm; range 6–9 mm ( n = 19). Proboscis length: mean 39.2 mm; range 31–46 mm ( n = 19). Wing length: mean 21.8 mm; range 19–24 mm ( n = 17).

Head. (Figs 4 B View Figure 4 , 6 B View Figure 6 ) Ground colour generally grey to black. Ocellar tubercle somewhat bulbous and developed, just evident above the upper eye margin in profile, with dense silvery pruinescence; width between eyes at the anterior ocellus 4.3–4.8 × the length of the anterior ocellus; anterior ocellus separated from posterior ocelli by shallow transverse groove; pile generally long (shorter than that of P. torquata and P. ora ), black. Frons trapezoid; width anterior to ocellar tubercle 0.8 × the width above antennal insertions; slightly to moderately swollen between antennal insertions and anterior ocellus; swelling recedes strongly towards eye margin; pruinescence relatively dense, brownish; pile black and white, sparse along lateral margins towards antennal insertions. Antenna with scape 1.5–2 × length of pedicel; first flagellomere subequal to the length of scape + pedicel; style longer than scape + pedicel + flagellomere 1; ground colour transitioning to a darker hue on the scape, style paler than remainder of antenna; scape, pedicel and flagellomere 1 with irregular silver to brown pruinescence; pedicel with both elongate and short, black and white pile, flagellomere 1 with short black pile basally on the dorsal side. Facial area bulbous in profile, with horizontal groove present; sublaterally irregular yellow-brown; with sparse silver to brown pruinescence, evenly distributed across face; pile brown to black, elongate, sparse, less dense than on frons. Gena with pile a mixture of golden and black, elongate, and dense, forming the beard. Proboscis 1.7–2.5 × 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 longer on the first segment.

Thorax (Fig. 3 B View Figure 3 ). Scutum dark grey to black; pruinescence mostly silver and brown, with pale grey to silvery pruinescence complete along the lateral sides of the scutum, joining on scutellum; median and paired sublateral vittae evident; medial vitta dark brown, narrow posteriorly, merging with sublateral vittae towards scutellum; paired sublateral vittae dark brown, straight, ending before scutellum; pile mostly black, 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, sparse compared to scutum; pile along posterior margin elongate, a mixture of black and pale, white or yellow, dense compared to disc of scutellum; with golden and black 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, black pile abutting white to golden pile; with tuft of pile on katatergite directed posteriorly, black and golden; katepimeron with pile absent, or sparse elongate white pile. Legs. Coxae yellow brown to dark brown; with pile mostly black or mostly off-white to golden, elongate, dense. Trochanters mostly blackish, with some yellow-brown colouring; pile short, very sparse. Femora yellow-brown, with dark marking on dorsal side of the distal end present; pile mostly black, mostly short, dense, but with elongate pile dorsally on proximal 1 / 3–1 / 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 mostly short pile, most dense on hind tibia. Tarsi red-brown to dark brown, hind tarsi tend to be darker. Wings (Fig. 5 B View Figure 5 ). Shape relatively slender; broadest just basal to termination of CuP on posterior margin; alula broad; costal margin close to straight, without distinct anteriorly curved flexure; Sc insertion on C aligned with insertion of M 4 on posterior margin of wing; R 1 inserted closer to R 2 + 3 than to Sc; insertions of Sc and R 1 well separated; short appendix just beyond fork on R 4 + 5 sometimes present; cross vein between M 1 and M 2 absent; cross vein between R 4 and R 2 + 3 absent; R 1 relatively straight; R 4 shallow bowing upward; R 5 shallow 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, appearing darker on anterior 1 / 2–1 / 3 of wing; posterior region of wing somewhat paler but never hyaline; isolated darker patches indistinct in pale region; the distinction between brown infuscation and hyaline membrane gradual, never striking. Tuft of pile on base of wing white. Haltere with pale brown to yellow stalk; bulb dark brown.

Abdomen (Fig. 3 B 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 (sometimes indistinct), extending from the posterior margin of T 1 to terminalia, usually not covering the full length of each tergite. Pile on tergites mostly black, both long and short, of intermediate density; along anterior margins of T 2 black or white to pale yellow, elongate, sparse; posterolateral pile on T 2 – T 4 black and white, 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 silverly with medial brown vitta in some specimens. Sternites with pile a mixture of black and white, mostly long, sparse; pile on S 1 and S 2 noticeably longer, white; pile on membrane adjacent to lateral margins of S 2 – S 4 typically with profuse, decumbent, elongate, pale yellow to golden.

Genitalia (Fig. 7 C, D View Figure 7 ). Hypandrium triangular in shape; broad, tapering abruptly 1 / 2 way up towards apex; laterally convex, bulging; 1.7 × longer than basal width; with apical 1 / 5 projecting past the top of the gonocoxites. Hypandrium vestiture short, sparse, on the apical 1 / 2. Gonocoxite apical 1 / 2 not parallel sided; gonocoxites widest in apical 1 / 3, narrowing apically; rounded apically. Gonocoxite vestiture on the lateral 1 / 2, of apical 1 / 2, mostly short, laterally projecting. Gonostylus narrowed medially; and narrow apical region. Phallus near parallel sided; narrowing apically.

Female. Same as male, except for genitalia dimorphism and the following characters: Head. Frons width anterior to ocellar tubercle 0.9 × the width above antennal insertions.

Geographical distribution.

Prosoeca marinusi occurs in a limited area around Nieuwoudtville and towards the Hantamsberg near Calvinia in the Northern Cape Province (Fig. 1 View Figure 1 ).

Biology.

Prosoeca marinusi can be found on the wing from early August to early November. The individuals found in the Hantamsberg appear to fly slightly later than those from lower lying areas. From specimen labels, P. marinusi appears to visit Lapeirousia jacquinii , Lapeirousia oreogena , Nemesia cheiranthus . Visits to Babiana framesii , Lapeirousia montana ( Barraclough, 2018) and Babiana vanzyliae ( https://www.inaturalist.org/observations/241874048 [accessed 10 February 2025]) have also been reported.

Comments.

Individuals from the Hantamsberg tend to be slightly darker in colouration than those from Nieuwoudtville, but the mean genetic differentiation between these populations is 2.06 % (range: 1.96 % – 2.27 %).