Research Article |
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Corresponding author: Genevieve L. Theron ( genevieveltheron@gmail.com ) Academic editor: Torsten Dikow
© 2025 Genevieve L. Theron, Allan G. Ellis, John M. Midgley.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Theron GL, Ellis AG, Midgley JM (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: 249-284. https://doi.org/10.3897/zookeys.1257.155954
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Prosoeca Schiner, 1867 is the most diverse genus of Nemestrinidae in Africa and is endemic to southern Africa. The 37 described species in this genus are all thought to be important pollinators for the plants that they visit. A recent phylogenetic study has shown that the diversity of this group is far larger than is formally recognised. Using of the phylogeny published by
Afrotropics, long-tongued flies, Namaqualand, Nemestrinidae, new species, taxonomy
Nemestrinidae is a relatively small family of ~ 280 species in 17 extant genera, distributed across all continents except Antarctica (
Prosoeca Schiner, 1867 (Diptera: Nemestrinidae: Nemestrininae) is the largest nemestrinid genus in Africa, with 37 valid species which are all thought to be endemic to southern Africa (
Prosoeca species are morphologically diverse, both in terms of size and colouration, often having elaborate patterning (
The unclear status of type specimens, fragmented nature of the literature and low number of specimens of certain species has hindered the revision of Prosoeca. However, the recent production of a molecular phylogeny (
DNA barcodes were generated to aid in identification and to emphasise the validity of the new species described. Where possible, new barcodes were generated from fresh specimens of both sexes from different populations to supplement barcodes generated for previous studies (Table
GenBank numbers of material used in the analysis, including source studies. Five of the six Prosoeca species treated are included and M. longirostris as an outgoup.
| Species | Identifier code | GenBank number | Reference |
|---|---|---|---|
| P. parva sp. nov. | FG48 | OP146648 |
|
| P. ora sp. nov. | 1410E07 | PV704777 | This study |
| 1410F01 | PV704775 | This study | |
| 1410F02 | PV704778 | This study | |
| P. marinusi | NV304 | MT487555 |
|
| 1410B02 | PV704781 | This study | |
| 1410B03 | PV704782 | This study | |
| 1410B04 | PV704783 | This study | |
| P. torquata | V9 | MT487549 |
|
| V4 | MT487546 |
|
|
| NN1 | MT487505 |
|
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| NO3 | MT487515 |
|
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| V12 | MT487552 |
|
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| U1 | MT487538 |
|
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| KB16 | PV704788 | This study | |
| ST5 | MT487536 |
|
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| AH11 | PV704786 | This study | |
| 3 | PV704780 | This study | |
| 2 | PV704779 | This study | |
| P. peringueyi | AP484 | OP146623 |
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| 1410C03 | PV704784 | This study | |
| 1410C01 | PV704784 | This study | |
| KB13 | PV704787 | This study | |
| VT13 | MT487554 |
|
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| NS10 | PV704790 | This study | |
| NGS-F06 | PV704789 | This study | |
| U5 | MT487540 |
|
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| NO4 | MT487516 |
|
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| NO6 | MT487517 |
|
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| U7 | MT487542 |
|
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| KB14 | MT487504 |
|
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| M. longirostris | 1410D08 | PV704776 | This study |
The retrieved COI sequences were checked for inconsistencies and assembled using Geneious Prime v. 2025.0. Sequences were submitted to GenBank (Table
This revision is based on all available Prosoeca material (including types) from the Greater Cape Floristic Region, belonging to the clade D4 from
Thirty-one barcodes from specimens across the range (Fig.
Mean p-distance within and between species barcodes. Grey highlighted numbers indicate mean within species p-distances. Unhighlighted numbers indicate between species mean p-distances.
| P. ora sp. nov. | M. longirostris | P. torquata | P. marinusi | P. peringueyi | P. parva sp. nov. | |
|---|---|---|---|---|---|---|
| P. ora sp. nov | 0.0805 | |||||
| M. longirostris | 0.164 | n/c | ||||
| P. torquata | 0.146 | 0.171 | 0.0381 | |||
| P. marinusi | 0.141 | 0.156 | 0.152 | 0.0103 | ||
| P. peringueyi | 0.139 | 0.161 | 0.119 | 0.142 | 0.0378 | |
| P. parva sp. nov. | 0.120 | 0.143 | 0.147 | 0.116 | 0.131 | n/c |
This clade can be distinguished from all other clades of Prosoeca by the combination of upturned longitudinal veins R2+3, R4, R5, M1, and M2 (Fig.
Body small- to large-sized (length 8–22 mm), abdomen with dark medial vitta, except in P. parva sp. nov. (Fig.
In Prosoeca, the pruinescence is largely responsible for the colour patterning, thus specimens that have been exposed to moisture or excessive ethyl acetate may easily lose the patterning, making identification difficult and in extreme cases impossible.
| 1 | Proboscis much longer than body length (Fig. |
2 |
| – | Proboscis shorter or of similar length to the body (Fig. |
4 |
| 2 | Wings with anterior infuscation never strikingly distinct from the paler posterior margin (Fig. |
P. marinusi Barraclough, 2018 |
| – | Wings with dark brown anterior infuscation strikingly distinct from posterior hyaline area (Fig. |
3 |
| 3 | Proboscis 14–24 mm, with a white band of pile anterior on the thorax, sublateral vittae present on the thorax but indistinct (Fig. |
P. torquata Theron, 2020 |
| – | Proboscis 23–35 mm, without dense white band of pile anterior on the thorax, distinct dark black sublateral vittae on the thorax (Fig. |
P. peringueyi Lichtwardt, 1920 |
| 4 | Wings with slight but distinct anterior curved flexure in males, dark brown anterior infuscation distinct from the hyaline area (female unknown) (Fig. |
P. aquilo sp. nov. |
| – | Wing margin close to straight without distinct anterior curved flexure in males, pale anterior infuscation somewhat distinct from the hyaline area (Fig. |
5 |
| 5 | Abdomen with dull grey pruinescent patterns (Fig. |
P. parva sp. nov. |
| – | Abdomen with regular pale grey, black and brown pruinescence patterning (Fig. |
P. ora sp. nov. |
Prosoeca
Schiner, 1867; Bezzi 1924;
Nemestrina westermanni (Weidemann, 1821), by original designation.
Prosoeca torquata Theron, 2020: 29.
Holotype
: South Africa • ♂ Northern Cape, Steinkopf, Kosiesberg; −29.12631, 17.55686; 3 Aug 2019; F. Grenier leg.;
South Africa • 1 ♂ Northern Cape: Kamiesberg: Leliefontein; 19 Oct. 2008; 34 visiting Satyrium erectum; T. van der Niet leg.;
(adapted from
Male. Body length: mean 15.7 mm; range 12–21 mm (n = 42). Intertegular width: mean 6.1 mm; range 4–8 mm (n = 12). Proboscis length: mean 17.8 mm; range 14–24 mm (n = 33). Wing length: mean 16.5 mm; range 12–19 mm (n = 14).
Head
. (Figs
Thorax
(Figs
Abdomen
(Fig.
Genitalia
(Fig.
Female. Same as male, except for genitalia dimorphism and the following characters: Head. Ocellar tubercle width between eyes at the anterior ocellus 3–3.5× the length of the anterior ocellus. Frons width anterior to ocellar tubercle 0.8× the width above antennal insertions.
Prosoeca torquata occurs between Namuskluft in Namibia (single
The P. peringueyi complex, including P. torquata, is known to visit many plant species (
Prosoeca marinusi Barraclough, 2018: 412.
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 A012376;
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 A015475, SAM-DIP A015476, SAM-DIP A015488;
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.
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.
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
Wings A. ♂ Prosoeca torquata
Thorax
(Fig.
Abdomen
(Fig.
Genitalia
(Fig.
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.
Prosoeca marinusi occurs in a limited area around Nieuwoudtville and towards the Hantamsberg near Calvinia in the Northern Cape Province (Fig.
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.
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%).
Prosoeca peringueyi
Lichtwardt, 1920: 98; Bezzi 1924: 175;
Lectotype
: South Africa: • 1 ♂ Northern Cape, Ookiep, Namaqua Div; R. Lightfoot leg.; Sep. 1990; SAM-DIP-A009013;
South Africa: • 1 ♂ 1 ♀, Northern Cape: Van Rhynsdorp; 28 Jul. 1927; Dr. Brauns leg.; Lapeirousia fissifolia, [illegible];
Large-sized (length 13–21 mm), grey body with intricate patterning on the thorax and the abdomen, thorax with two dark black sub-lateral vittae extending to the transverse suture, legs dark brown, proboscis length 1.55 ± 0.02× the length of the body (range of un-extended proboscis length 23–35 mm), wings with smoky brown patterned infuscation on the anterior 1/2 of the wing and cross-vein between R4 & R2+3 complete in specimens from the northern part of the range (north of Calvinia). Prosoeca peringueyi, P. marinusi, and P. torquata 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 peringueyi and P. torquata have a dark smoky brown wing patterning that is strikingly distinct from the almost hyaline posterior wing membrane, while P. marinusi has a paler brown wing patterning that is never strikingly distinct from the lightly infuscated posterior wing membrane (Fig.
Male. Body length: mean 18.1 mm (n = 43); range 13–21 mm. Intertegular width: mean 7.0 mm; range 5–8 mm (n = 11). Proboscis length: mean 29.2 mm; range 23–35 mm (n = 29). Wing length: mean 19.6 mm; range 18–21 mm (n = 19).
Head
. (Figs
Thorax
(Fig.
Abdomen
(Fig.
Genitalia
(Fig.
Female. Same as male, except for genitalia dimorphism and the following characters: Head. Frons width anterior to ocellar tubercle 0.8× the width above antennal insertions.
Prosoeca peringueyi is the most widespread species in this clade. It occurs from Khuboes near the Namibia/South Africa border in the north to Piekenierskloof pass in the Western Cape Province in the south (pers. obs., A.G. Ellis), with a distribution gap within the Knersvlakte (Fig.
The P. peringueyi complex is known to visit many plant species (
Prosoeca peringueyi has a degree of genetic differentiation between the populations north and south of the Knersvlakte (mean 6.27%). This genetic disjunction is supported by a difference in wing venation, with the cross vein between R4 and R2+3 just beyond fork of R4 and R5 present north of the Knersvlakte and absent in the south. As the wing vein character is not functional and the genetic difference below the usual threshold for species delineation, we consider this to be a single species.
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.;
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.
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
Thorax
(Fig.
Abdomen
(Fig.
Genitalia
(Fig.
Female. Unknown
Only known from a single locality in the Kamiesberg mountains near Leliefontein in the Northern Cape of South Africa (Fig.
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.
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.
Holotype
: South Africa: • 1 ♂, Northern Cape: Hantam Botanical Garden; 27 Aug. 2017; T. van der Niet leg.;
South Africa: • 1 ♀ Western Cape: Maitjiesfontein Koppie: E. Soetwater; 07 Sep. 2019; Allan Ellis leg.;
Medium-sized (length 10–17 mm), thorax dark, scutellum and thorax with conspicuous grey border, abdomen black but tergites interrupted medially by a pale grey band, often flaring out posteriorly, and a dark brown median vitta, femora dorsally darker than tibia and tarsi, proboscis length 0.7 ± 0.02× the length of the body (range of un-extended proboscis length 6–11 mm). Prosoeca ora sp. nov. can be distinguished from all other species in the clade by the distinct grey, brown and black patterning on the abdomen (Figs
Male. Body length: mean 13.8 mm; range 10–17 mm (n = 19). Intertegular width: mean 6.5 mm; range 4–8 mm (n = 9). Proboscis length: 9.7 mm; range 6–11 mm (n = 18). Wing length: mean 15.4 mm; range 11–18 mm (n = 19).
Head
. (Figs
Thorax
(Fig.
Abdomen
(Fig.
Genitalia
(Fig.
Female. Same as male, except for genitalia dimorphism and the following characters: Head. Ocellar tubercle width between eyes at the anterior ocellus 3.4–4.5× the length of the anterior ocellus. Frons width anterior to ocellar tubercle 0.6–0.7× the width above antennal insertions. Facial area with horizontal groove present (less pronounced than in males). Legs. Femora dark brown to black (sometimes closer to red-brown).
Prosoeca ora sp. nov. has been recorded from Nieuwoudtville in the Northern Cape to Matjiesfontein and Touws River in the Western Cape (Fig.
Prosoeca ora sp. nov. is on the wing from early August to mid-October in the winter-rainfall region of the Western and Northern Cape provinces of South Africa. This species has been recorded visiting Pteronia incana, Dimorphotheca cuneata, Babiana vanzyliae, Hesperantha cucullata and yellow Pseudoselago (Scrophulariaceae). Additionally, based on the representative specimen accessioned into
From the Latin ora = edge or rim; referring to the characteristic grey pruinescence on the dark thorax forming a distinct border. To be treated as a noun in apposition.
The single female specimen from Soetwater (
Holotype
: South Africa: • 1 ♂ Northern Cape, Calvinia: Hantamsberg; 3 Sep. 1994; 30; Felicia;
Relatively small species (length 8–11 mm), thorax dark without distinct central markings, thorax and scutellum with a conspicuous grey border, abdomen uniformly black, proboscis length 0.57 ± 0.04× the length of the body (range of un-extended proboscis length 4 mm–6 mm), femora very dark with pale red-brown tibia and tarsi and conspicuously short antennal style. Prosoeca parva sp. nov. can be distinguished from all other species in the clade by the apparent lack of patterning on the abdomen (Fig.
Male. Body length: mean 9.8 mm; range 8–11 mm (n = 4). Intertegular width: mean 3.8 mm; range 3–4 mm (n = 4). Proboscis length: mean 5.6 mm; range 4–6 mm (n = 4). Wing length: mean 11.2 mm; range 11–12 mm (n = 4).
Head
. (Figs
Thorax
(Fig.
Abdomen
(Fig.
Genitalia
(Fig.
Female. Same as male, except for genitalia dimorphism and the following characters: Head. Ocellar tubercle width between eyes at the anterior ocellus 3.8–4.5× the length of the anterior ocellus. Frons width anterior to ocellar tubercle 0.8× the width above antennal insertions. Wings. Sharp short appendix just beyond fork on R4 sometimes present.
Known from only a single locality on the Hantamsberg near Calvinia (Fig.
Known to be on the wing in September and has been recorded visiting flowers in the Asteraceae genus Felicia. A male and a female were caught mating on a mountain peak, potentially hill-topping (
From the Latin parva = little; referring to the small size of this species compared to all other species in this clade. To be treated as a noun in apposition.
Based on morphological and molecular data, the spring-flying Namaqualand clade of Prosoeca (clade D4 in
The low-lying plains of the Knersvlakte region (formerly a palaeochannel of the proto-Orange River) seem to represent an interesting geographical break in species distribution in this group, with no Prosoeca species collected from this area during spring. The only species that straddles this geographic break is P. peringueyi, which has a strong geographic disjunction across the Knersvlakte (Fig.
As with most Prosoeca species, the species investigated here have almost all been found foraging on flowers and many specimens had substantial amounts of pollen on their bodies (Fig.
We thank Burgert Muller and Torsten Dikow for detailed and insightful comments on the manuscript. Furthermore, we thank Cassandra Barker for assistance in the field, Dr Terence Bellingan for providing us with material from
The authors have declared that no competing interests exist.
No ethical statement was reported.
No use of AI was reported.
This project was funded by DIPoDIP (Diversity of Pollinating Diptera in South African biodiversity hotspots) which is financed by the Directorate-general Development Cooperation and Humanitarian Aid through the framework agreement with KMMA. GT was a post-doctoral fellow funded by the NRF-PDP programme (UID 144827).
Conceptualization: JMM, GLT, AGE. Data curation: GLT. Funding acquisition: JMM. Methodology: GLT. Resources: AGE, JMM. Visualization: GLT. Writing - original draft: GLT. Writing - review and editing: AGE, JMM.
Genevieve L. Theron https://orcid.org/0000-0002-1071-9014
Allan G. Ellis https://orcid.org/0000-0001-6310-2870
John M. Midgley https://orcid.org/0000-0003-1203-3750
All of the data that support the findings of this study are available in the main text or Supplementary Information.
A condensed and summarised version of the phylogenetic tree from
Data type: eps
Explanation note: The bar on the right-hand side of the tree indicates the named genera, while the black portion of the bar represents Prosoeca sensu lato. The number of species within a clade is shown in brackets.