RESEARCH ARTICLE

 

The occurrence of the hover fly genus Eristalis Latreille, 1804 (Diptera: Syrphidae) in the Afrotropical region

 

 

M. De Meyer^I; G. Goergen^II; T. Bellingan^{III, IV}; J. Midgley^{IV, V}; K. Jordaens^I

^IRoyal Museum for Central Africa, Invertebrates Section, Tervuren, Belgium
^IIInternational Institute of Tropical Agriculture (IITA), Biodiversity Centre, Cotonou, Benin
^IIIAlbany Museum, Department of Entomology and Arachnology, Makhanda, South Africa
^IVDepartment of Zoology and Entomology, Rhodes University, Makhanda, South Africa
^VKwaZulu-Natal Museum, Department of Natural Sciences, Pietermaritzburg, South Africa

Correspondence

 

 

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ABSTRACT

The Afrotropical hover flies placed in the genus Eristalis Latreille, 1804 (Diptera: Syrphidae) are revised and the taxonomic history of the placement, and identity, of the different species is presented. Five species are recognised, of which only three can be clearly defined: E. pallidibasis (Bigot, 1891), E. plumipes Bezzi ,1912, and E. tenax (Linnaeus, 1758). Eristalis apis Curran, 1939 syn. nov. is proposed as a junior synonym of E. pallidibasis (Bigot, 1891). Eristalis convexifacies Macquart, 1850 is known only from a badly damaged holotype. The identity of Simoides trichopus Bigot, 1891, (now considered to be an Eristalis) is uncertain as its type material could not be traced and the original description lacks sufficient detail. For the time being, S. trichopus is considered a nomen dubium. An identification key and detailed redescriptions are provided. Eristalis pallidibasis, E. plumipes and E. tenax are easily identified using DNA barcoding. The relationship of Afrotropical Eristalis with Afrotropical representatives of other eristaline genera is briefly discussed based on morphological data.

Keywords: DNA barcoding, Eristalinae, flower flies, hover flies, taxonomy

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INTRODUCTION

Hover flies or flower flies (Diptera: Syrphidae) are one of the more diverse families of true flies with over 6 500 species described worldwide (Evenhuis and Pape 2024). The Afrotropical fauna, however, is poorly known with slightly over 600 species (Kirk-Spriggs and Sinclair 2017) which is considered an underestimation due to limited faunistic and taxonomic work and studies conducted in the region (Ssymank et al. 2021). Because of the varied larval life history (Ssymank et al. 2021), the group is a useful indicator of biodiversity for several ecosystems. In addition, they play an economic and ecological role as pollinators, biocontrol agents, and decomposers (e.g., Inouye et al. 2015). However, in these contexts, proper identification is required to link a specific taxon to a particular ecological role in its ecosystem. Recently, the lack of revisions or identification keys, as outlined in Whittington (2003) and Ssymank et al. (2021), has been addressed for several Eristalini genera (De Meyer et al. 2020a, 2020b, 2024; Jordaens et al. 2021; and references in these).

The genus Eristalis Latreille, 1804 is a diverse group of close to 100 species with their main distribution in the Holarctic region (Thompson 2003). It is placed under the subfamily Eristalinae, tribe Eristalini and subtribe Eristalina. Bezzi (1915), who provided the first comprehensive list of Afrotropical Syrphidae, placed the following eight species under Eristalis: E. tenax (Linnaeus, 1758), E. dasyops Wiedemann, 1819, E. plumipes Bezzi, 1912, E. haplops Wiedemann, 1830, E. trichopus (Bigot, 1891), E. pallidibasis (Bigot, 1891), E. meromacriformis Bezzi, 1915, and E. convexifacies Macquart, 1850. Since then, several changes have been made to the taxonomy of Eristalis: E. meromacriformis has been placed into Meromacroides (Curran, 1927), E. haplops into Eristalinus (Smith & Vockeroth, 1980), and E. dasyops into Mallota (De Meyer et al., 2024); E. apis Curran, 1939 was described, and the generic concept, as well as subgeneric subdivision, has been discussed in detail (see Thompson 2003 for a review). Currently, six species are listed under this genus for the Afrotropical region: E. apis, E. convexifacies, E. pallidibasis, E. plumipes, E. tenax, and E. trichopus (Smith and Vockeroth 1980). Ssymank et al. (2021) erroneously mentions seven species. All of these appear to be indigenous to the Afrotropical region, except for E. tenax, the (common) drone fly, which is of Palaearctic origin but introduced in all other regions worldwide, except Antarctica (El-Hawagry and Gilbert 2019 and references therein). For E. trichopus, the type material could not be traced while the presumed type of E. convexifacies (specimen labelled as type in the NHMUK collection) is in such poor condition (see Figure 4) that no real diagnostic characteristics could be discerned.

 

 

 

 

Recent expeditions by different research groups have expanded the material available for the abundant species (i.e., E. pallidibasis, E. plumipes, E. tenax), including specimens suitable for molecular analysis. The main objectives of this study were, therefore, to provide a clear diagnostic description of the representatives of the genus Eristalis found in the Afrotropical region (to the same standard as the rest of the Eristalina), to present an identification key for those species that can be unambiguously identified, and to discuss their interrelationships based on morphological data.

 

MATERIAL AND METHODS

This section largely follows the same outlines and methodologies with regard to terminology followed, identification key, illustrations and DNA barcoding, as described in previous recent taxonomie revisions published by us (e.g., De Meyer et al. 2020a,b, 2024; Jordaens et al. 2021).

Material examined

Speeimens from the following institutional and private eolleetions were studied:

• AMGS: Albany Museum, Makhanda (Grahamstown), South Africa

• AMNH: American Museum of Natural History, New York, USA

• ANHRT: African Natural History Research Trust, Leominster, UK

• BMSA: Bloemfontein Museum, Bloemfontein, South Africa

• DMF: Dijon Museum, Dijon, France

• IITA: International Institute of Tropical Agriculture, Cotonou, Benin

• MCSNG: Museo Civico di Storia Naturale 'Giacomo Doria, Genoa, Italy

• NHMUK: The Natural History Museum, London, UK

• NMSA: KwaZulu-Natal Museum, Pietermaritzburg, South Africa

• OXUM: Oxford University Museum, Oxford, UK

• RBINS: Royal Belgian Institute of Natural Sciences, Brussel, Belgium

• RMCA: Royal Museum for Central Africa, Tervuren, Belgium

• SCPC: S. Cavaillès personal collection, Kergoc, France

Fieldwork

Part of the material was collected by the authors of the present paper between 1994-2023. Hover flies were collected from agricultural land and adjacent environment (no private grounds were accessed without prior consent by the owners). Collecting in Togo was done in collaboration with IITA, which is a non-profit international organisation and a member of the Consultative Group on International Agricultural Research (CGIAR) Consortium. In Togo, IITA has a close partnership with the National Plant Protection Service and the University of Lomé through which material was obtained, and no specific permissions were required. Permits for collecting in Malawi were obtained from the Forestry Research Institute of Malawi (FRIM). Permits for collecting in South Africa were obtained from Cape Nature (CN44-87-27032), the Eastern Cape Department of Economic Development, Environmental Affairs and Tourism (CRO 132/19 CR; 133/19 CR) and Ezemvelo KZN Wildlife (OP29-2020, OP2823-2020, OP2920-2021, OP3213-2022, OP43-2024). None of the collected species occur on red lists of endangered species or are considered to be endangered/threatened, nor is any ranked in the IUCN Red List nor protected by CITES.

Morphological study

Morphological observations were made with a Leica MZ8 stereomicroscope and morphological terminology largely followed Thompson (1999). All species recognised as valid after our study were redescribed. Body length and wing length ranges given are minimum and maximum values observed in the studied material. Body measurements were taken between the frons and the posterior end of tergum 4 (in lateral view), while wing measurements were taken between the tegula and the apex of the wing. Stacking digital images were made using the set-up as outlined in Brecko et al. (2014) and stacking was done with the Zerene Stacker software (https://zerenesystems.com/cms/home). For those species for which no material could be obtained, the original descriptions are repeated, translated and the possible identity of the species is commented upon. Literature references are given for original taxon descriptions under each species.

DNA barcoding

Procedures for DNA barcoding (DNA extraction, PCR and DNA sequencing) followed Jordaens et al. (2015). Sequences were assembled in Geneious R10 (https://www.geneious.com). A Neighbor-Joining (NJ) tree (Saitou and Nei 1987) was constructed using uncorrected p-distances in MEGA v.11 (Tamura et al. 2021) (Figure 24) and pairwise p-distances within and among species were calculated. We obtained 27 DNA barcodes of Eristalis which were submitted to GenBank. To this dataset we added ten Afrotropical Eristalis DNA barcodes from GenBank (accession numbers KR830983-KR830992; see Jordaens et al. 2015) A DNA barcode of Mallota dasyops (Wiedemann, 1819) (GenBank accession number PP823961) was used to root the tree. Table 1 summarises the material, with GenBank accession numbers, included in the NJ tree.

 

RESULTS

Key to species of the genus Eristalis occurring in the Afrotropics

The species that could not be unambiguously identified are excluded from this key (see Introduction).

1a) Head: eyes with distinct longitudinal stripes of longer and denser pilosity in central part (Figure 10). Thorax: anterior anepisternum with long pile (Figure 15). Legs: metafemur slender, length at least six times as long as width (Figure 16). Abdomen: tergum 1 black (Figure 23) .................... E. tenax

1b) Head: eyes without distinct stripes of longer and denser pilosity, pilosity evenly short and dispersed in central part (Figures 6, 8). Thorax: anterior anepisternum bare (Figures 11, 13). Legs: metafemur thickened, length at most four times as long as width (Figures 12, 14). Abdomen: tergum 1 yellow to orange (Figures 20-22) .................... 2

2a) Abdomen: terga covered with dispersed short erect pile (Figures 1, 20-21). Legs: metatibia with short pile, length at most half the tibia width (Figure 12). Male head in dorsal view: eye contiguity for 2.5-3 times the ocellar triangle length (Figure 6) .................... E. pallidibasis

2b) Abdomen: terga covered with dense long pile providing a woolly appearance (Figures 2, 22). Legs: metatibia with longer pile, subequal in length to the tibia width (Figure 14). Male head in dorsal view: eye contiguity for at most twice the ocellar triangle length (Figure 8) .................... E. plumipes

Redescriptions

Eristalis pallidibasis (Bigot, 1891)

Simoides pallidibasis Bigot, 1891: 374.

Eristalis apis Curran, 1939: 3. Syn. nov.

Eristalis apis Curran - Smith & Vockeroth 1980: 503 - Dirickx 1998: 31 - De Meyer et al. 1995, 1: 8 - De Meyer 2001: 92 - Whittington 2003: 591.

(Figures 1, 5-6, 11-12, 17, 20-21)

Differential diagnosis

Together with E. plumipes, this species can be differentiated from the non-native E. tenax by the thickened metafemur (slender in E. tenax), the bare anterior anepisternum (pilose in E. tenax), the pilosity of the eyes being evenly short and dispersed in the central part (with longitudinal bands of denser and longer pilosity in E. tenax), and the yellow to orange colour of the first abdominal tergum (black in E. tenax). The species can be differentiated from E. plumipes predominantly by the pilosity of the abdominal terga being short and more dispersed (pilosity longer and denser - resembling a woolly coverage - in E. plumipes).

Material examined

Holotype. ♀ CÔTE d'IVOIRE, Assinie, July-August 1886, Ch. Alluaud, NHMUK (BMNH(E) 230757, Bigot collection). Holotype. E. apis. S DEMOCRATIC REPUBLIC OF CONGO, Stanleyville [=Kisangani], March 1915, Lang-Chapin, AMNH. Paratypes. E. apis. 3S and 32♀ (one labelled as allotype) with same data; 1♀ from Lubutu [Congo (DR)] (AMNH).

Non-type material

ANGOLA: 1♀, Moxico, Lungwebungu, 7km N bridge, 11.XI.2022, T. Bellingan, NMSA. BENIN: 1♂ 1♀, Niaouli, 2.II.2014, G. Goergen, IITA. CÔTE d'IVOIRE: 1♀, Near Palmindustrie, about 15k W of Fresco, 24.IV.1989, J.G.H. Londt, NMSA. DEMOCRATIC REPUBLIC OF CONGO: 1♀, Kasai, Dekese, Itunda, 24.I.1960, F.J. François, RBINS; Eala, 2♂ 1♀, February 1936, J. Ghesquière, RBINS; 1♀, Eala, March 1936, J. Ghesquière, RBINS; 1♀, Katanga, Elisabethville [=Lubumbashi], Kimilolo, 1.XII.1929, M. Bequaert, RMCA; 2♂, Lubutu, 22.I.1915, AMNH; 1♂, Equateur, Moma, June 1925, J. Ghesquière, RMCA; Stanleyville [=Kisangani], 6♀, March 1915, Lang-Chapin, AMNH; 2♂ 12♀, March 1915, Lang-Chapin, RMCA. 1♀, 4.IV.1915, Lang-Chapin, AMNH; 1♀, 4.IV.1915, Lang-Chapin, RMCA; 1♂ 2♀, 2.IV.1915, Lang-Chapin, RMCA; 2♀, 7.IV.1915, Lang-Chapin, RMCA; 1♀, 10.IV.1915, Lang-Chapin, RMCA; 1♂, 7.VII.1915, Lang-Chapin, RMCA. EQUATORIAL GUINEA: 1♀, Fernando Poo [=Bioko Is.], Bahia de S. Carlos, February 1902, L. Fea, MSCNG. REPUBLIC OF THE CONGO: Nouabale-Ndoki NP, Mbeli Camp, 3♀, 3-10.X.2022, Dérozier et al., ANHRT; 1♂ 12♀,14-20.II.2023, Bakala et al., ANHRT; Nouabale-Ndoki NP, Mondika Camp, 6♀, 7-14.II.2023, Bakala et al., ANHRT; 1♀, 7.IV-6.V.2023, Bakala et al, ANHRT. SOUTH AFRICA: 1♀, KwaZulu-Natal, 32 Panorama Rd, Hilton, 20.II.2020, J. Midgley, NMSA; 2♂, KwaZulu-Natal, iSimangaliso Wetland Park, kuMfazana hide on forest loop, 14.X.2021, K. Jordaens, RMCA; KwaZulu-Natal, iSimangaliso Wetland Park, uMthoma aerial walk, 1♂, 13.X.2021, T. Bellingan, K. Jordaens and J. Midgley, AMGS; 1♂; 13.X.2021, T. Bellingan, K. Jordaens and J. Midgley, NMSA; 2♂, KwaZulu-Natal, iSimangaliso Wetland Park, Vlei loop, 12.X.2021, T. Bellingan, K. Jordaens and J. Midgley, NMSA; 1♂, KwaZulu-Natal, Kosi Bay N R, 9-13.X.2011, J.G.H. Londt, NMSA; 1♂, KwaZulu-Natal, Kosi Bay Nature Reserve (iSimangaliso Wetland Park), 30.XI-2.XII.1982, B.R. Stuckenberg, D.A. Barraclough, and J.G.H. Londt, NMSA; 1♀, KwaZulu-Natal, Mtunzini, Raphia Palm Boardwalk, 12.XI.2020, J. Midgley and T. Bellingan, NMSA; KwaZulu-Natal, Saint Lucia, iGwalagwala trail, 2♂, 15.X.2021, K. Jordaens, RMCA; 1♂, 9.X.2021, T. Bellingan, K. Jordaens and J. Midgley, AMGS. TOGO: 2♂, Kloto, March-April 2020, G. Goergen, RMCA; Kloto forest, 1♀, December 2003, G. Goergen, IITA; 3♂ 3♀, March 2004, G. Goergen, IITA; 1♀, April 2004, G. Goergen, IITA; 1♀, February 2005, G. Goergen, IITA; 1♀, June 2016, G. Goergen, RMCA; 1♂, June 2017, G. Goergen, RMCA; 1♀, February 2021, G. Goergen, RMCA.

Redescription

Body length: 12.7-16.7 mm. Wing length: 9.5-11.0 mm.

Male

Head (Figures 5-6). Eye with short pale orange-brown to pale yellow pile, towards posterior margin gradually shortening and more dispersed, postero-ventrally near occiput largely bare; holoptic, eye contiguity 2.5-3 times the length of the ocellar triangle. Frons protruding, in lateral view extending as far as facial tubercle; ground colour black; area dorsal of antennae mainly slightly shiny, with predominantly long pale yellow pile, intermixed with a few black pile; with weak pale brown pollinosity, at eye margins denser pollinose. Ocellar triangle black, with short black pile; anterior part of ocellar triangle area with silvery pollinosity; with short pale brown pile or bare. Face ground colour black to brown, posteroventrally near gena with an orange-brown to yellow-brown macula; with brown pollinosity, along eye margins denser pollinose, facial tubercle sometimes non-pollinose; with dispersed pale yellow pile along lateral margins for one-third of facial width on each side, otherwise bare; facial tubercle round and strongly pronounced. Antennal segments black-brown, postpedicel black, slightly longer than wide, with silvery pollinosity, scape and pedicel with some black pile; arista bare, brown basally and black apically. Thorax (Figure 1). Scutum black; slightly shiny with brown pollinosity, with long pale brown to yellow-brown pile sometimes intermixed with black pile; along anterior margin, near transverse suture and in parts of posterior third with grey to yellowish pollinosity and pale yellow pile. Postpronotum yellow, with yellow-white pile, sometimes intermixed with a few black pili. Scutellum yellow, anteromedially yellow-brown, with long pale yellow pile, anterior third sometimes with darker pile, though anterior margin always with narrow band of pale pile. Ground colour of pleura (Figure 11) black, posterior anepisternum, katepisternum, anterior anepimeron, and katatergite with long pale brown to pale yellow pile, otherwise bare, brown pollinose.

Legs. Femora mainly yellow-brown to orange-brown, posteriorly darker, ventrally in posterior part more extensively so with black macula covering two-thirds of entire length; with short to long dense pale yellow to yellowish brown pile, ventrally with short and black pile. Metafemur (Figure 12) thickened, in anterior view medial part about twice as broad as apex; black-brown to black but anterior third yellow-brown to orange-brown, ventrally dense black pilose in distal half, in addition to few dispersed long pale yellow hairs. Tibiae predominantly black to black-brown, with short black pile intermixed with some pale yellow to yellowish brown pile; metatibia (Figure 12) slightly curved and thicker than pro- and mesotibae, with short to medium length black pile, pile always shorter than width of tibia. Tarsal segments orange-brown to brown, with short brownish pile. Wing (Figure 17). Largely hyaline, anterior part slightly infuscated; most areas microtrichose. Weakly developed stigmal cross-vein present between distal end of vein Sc and middle of vein R₁. Cell r₁ closed with distinct petiole. Vein R 4+5 sinuate, with or without auxiliary vein.

Abdomen (Figure 20). Mainly shining black, with pale yellow to white pile. Tergum 1 ground colour orange, sometimes more yellowish, with long white pile, white pollinose. Tergum 2 with a pair of yellow-orange rectangular maculae, which are broader along lateral margins; narrowly separated by medial black line, sometimes touching and forming fascia; along posterior margin narrowly orange, predominantly short pale yellow pilose, medially longer pilose, posterior margin with black pile. Anterior margin of tergum 3 narrowly yellow-orange, medially interrupted, sometimes anterior half more extensively yellow-orange, posteriorly sometimes also narrowly yellow-orange medially, with short pale yellow pile, along lateral margins somewhat longer pile, posterior fourth with short black pile, sometimes more extensively so; partially brown pollinose. Tergum 4 with short, pale yellow pile in anterior half or further, with black pile in posterior half, sometimes more extensively so, partially grey to brown pollinose. Sterna predominantly black, anterior 1-3 partially yellow-orange, with very long, dispersed pale yellow pile.

Female

As male except for the following characters: eyes widely dichoptic, frons black, slightly shiny and more extensively so in area dorsal of antennae, frons grey pollinose except the brown dorsal third, abdominal terga sometimes with orange maculae and fasciae more extensive than in male (as in Figure 21, but see comments).

Distribution

Angola, Benin, Côte d'Ivoire, Democratic Republic of Congo, Equatorial Guinea, Republic of the Congo, South Africa, Togo. Also reported from Kenya (De Meyer 2001) but this record needs reconfirmation.

Comments

The precise identity of this species was unclear. The only reference to specimens identified as this species, after the original description by Bigot, is by Curran (1927) who lists a series of specimens from the Democratic Republic of Congo as being E. pallidibasis. Subsequently, Curran (1939) placed these under Mallota extrema (Loew, 1858), and these are now considered to be Mallota hircus De Meyer, Goergen, Midgley & Jordaens, 2024 (see De Meyer et al. 2024 for discussion on the identity of this series). Curran (1939) described a new species, Eristalis apis, based on material collected in the Democratic Republic of Congo. This series was presumably initially identified as Senaspis dasyops by him (Curran 1927), as he specifically mentions the similarity between this series and material of E. plumipes (see Curran 1927: 67). Comparison of the type material of E. apis and E. pallidibasis showed that they are identical in morphological appearance and thus the former is hereby considered a junior synonym of the latter. Two female specimens from Stanleyville [Kisangani; DRC], conspecific with the allotype and longer series, one female from Katanga (DRC), and one female from Kloto forest (Togo) show more extensive yellow-orange markings on the abdominal terga, in particular on tergum 3 (Figure 21), similar to what is observed in E. plumipes (Figure 22). No other morphological differences could be observed with the other specimens. One specimen (from Togo) could be DNA barcoded and shows a p-distance with E. plumipes and E. apis of p= 0.05 and p = 0.09, respectively, which is comparable to the p-distance between E. plumipes and E. apis (p-distance: 0.09) (Figure 24). As the material is limited and no male specimens could be discerned, we for the time being do not consider it here as a separate species. However, E. pallidibasis as currently defined could represent a species complex and warrants further investigation.

Eristalis plumipes Bezzi, 1912

Eristalis plumipes Bezzi, 1912: 433.

Eristalis plumipes Bezzi - Curran 1939: 3 - Smith & Vockeroth 1980: 503 - Dirickx 1998: 32 - Whittington 1998: 192 -Whittington 2003: 591 - Sinzinkayo et al. 2017: 35.

Senaspis plumipes (Bezzi) - Curran, 1927: 67.

(Figures 2, 7-8, 13-14, 18, 22)

Differential diagnosis

Together with E. pallidibasis, this species can be differentiated from the non-native E. tenax by the thickened metafemur (slender in E. tenax), the bare anterior anepisternum (pilose in E. tenax), the eye pilosity being evenly dispersed (with longitudinal lines of denser pilosity in E. tenax), and the yellow to orange colour of the first abdominal tergum (black in E. tenax). It can be differentiated from E. pallidibasis predominantly by the pilosity of the abdominal terga being dense and resembling a woolly coverage (shorter and more dispersed in E. pallidibasis).

Material examined

Syntypes. 1♀, EQUATORIAL GUINEA: Fernando Poo Is. [=Bioko Is.], Moka, February 1902, L. Fea, MCSNG. This syntype is hereby designated as lectotype. 1♀, GUINEABISSAU, Bolama, June-December 1899, L. Fea, MCSNG. Hereby designated as paralectotype.

Non-type material

BENIN: Ahozon, 1♂, September, 2005, G. Goergen, IITA; 1♂, 22.I.2012, G. Goergen, IITA; 1♂, Aplahoué, February 2016, G. Goergen, IITA; Niaouli, 2♂ 2♀, 10.XII.2013, K. Jordaens and G. Goergen, RMCA; 1♂, 22.I.2012, G. Goergen, IITA; 1♂, 10.XII.2014, G. Goergen, IITA; 1♂, November 2016, G. Goergen, IITA; 1♂, November 2021, G. Goergen, IITA; 1♂, December 2022, G. Goergen, IITA; Sérou, 1♂, September 2005, G. Goergen, IITA; 1♂, February 2006, G. Goergen, IITA; 1♂, December 2014, G. Goergen, IITA; November 2016, G. Goergen, 8♂ 1♀, RMCA; 1♂ 1♀, IITA; Tanougou waterfalls, 1♂, 10.XII.2014, G. Goergen, RMCA; 2♂ 1♀, 28.IV.2018, G. Goergen, IITA; 1♀, 15.I.2020, G. Goergen, RMCA; 1♂, 21.XI.2021, G. Goergen, RMCA. BURUNDI: 1♂ 3♀, Kanyinya, June-December 1946, Dames de Marie, RMCA. CÔTE d'IVOIRE: 1♀, Lamto, Toumodi, July-August 1968, C. Girard, DMF. DEMOCRATIC REPUBLIC OF CONGO: 1♀, Lubumbashi Maison, 24.I.1971, Bouvy, NMSA; 1♀, Albertville [=Kalemie], July 1954, H. Bomans, RMCA; 1♀, Equateur, Bokuma, December 1951, P. Lootens, RMCA; Eala, 1♂, 19.VII.1935, J. Ghesquière, RBINS; 1♀, February 1936, J. Ghesquière, RBINS; 1♂, April 1936, J. Ghesquière, RBINS; 1♂, 19.VIII.1936, J. Ghesquière, RBINS; 1♂, November 1936, J. Ghesquière, RBINS, 1♂, Tshuapa, Ikela, 1955, R.P. Lootens, RMCA; 1♂ 10♀, Lualaba, Kapolowe, 1959, J.P. Herremans, RMCA; 2♂ 2♀, Wamba, Kibali-Ituri, Epulu, October 1956, M. Poll, RMCA; 1♂, Kivu, Lac Vert (forêt route Goma-Sake), 29.XI.1952, J. Verbeke, RBINS; 1♂, Ubangi, Longo, 1936, D. Kowalevsky, RMCA; 1♂, Ouellé, 1917, A. Dubois, DMF; 1♀, Lukolela, 4.II.1929, H.J. Bredo, RMCA; 1♀, Kivu, Nzomba (Amont, près Mwana), 1952, Froidebise, RMCA; 1♂, Rutshuru, April 1938, J. Ghesquière, RBINS; Stanleyville [=Kisangani], 1♂ 1♀, March 1915, Lang and Chapin, AMNH; 1♂, 10.IV.1915, Lang and Chapin, AMNH; 1♂ 2♀, March 1915, Lang and Chapin, RMCA; 4♀, April 1915, Lang and Chapin, RMCA; 1♀, 2.IV.1915, Lang and Chapin, RMCA; 1♂, 10.IV.1915, Lang and Chapin, RMCA; 1♂, 1.IV.1915, Lang and Chapin, RMCA; 1♂, 7.IV.1915, Lang and Chapin, RMCA; 1♀, March 1936, J. Ghesquière, RMCA; 1♀, Lomami, Sungu Mwana, R. Bukama, près Kamina, 9.II.1951, Buls, RMCA; 1♀, T. Masisi, Kalenga, 1951, Dedobelaere, RMCA. MALAWI: 1♀, Kasungu, 9.XII.1980, B.R. Stuckenberg and J.G.H. Londt, NMSA; 13♂ 4♀, Mulanje Mountain Forest Reserve, 12-15.XI.2016, K. Jordaens, RMCA; 1♂, Mulanje mtn., Likhubula, 12-14.XI.2016, K. Jordaens, RMCA; 3♂ 4♀, Mulanje Village, 8km SE, 30.XI.1980, B.R. Stuckenberg and J.G.H. Londt, NMSA; 3♂ Zomba Plateau, Kuchawe trout farm, 8-11.XI.2016, K. Jordaens, RMCA; 1♀, Zomba, trout farm, 15-19.XI.2016, K. Jordaens, RMCA. REPUBLIC OF THE CONGO: 1♀, env. Brazzaville, 1908, E. Roubaud and A. Weiss, DMF. RWANDA: 1♀, Kibungu, October-December 1937, R. Verhulst, RMCA; 1♂ 2♀, Kigali, Rubongo, 11.V.1970, O. Van Laere, RMCA. SENEGAL: Dindefelo, 1♂, 25.XII.2015, S. Cavaillès, SCPC; 2♂ 1.I.2016, S. Cavaillès, SCPC; 2♂, 4.XI.2016, S. Cavaillès, SCPC. SOUTH AFRICA: 1♂, KwaZulu-Natal, Ingwavuma, 21.II.1979, J.G.H. Londt, NMSA; 2♂, KwaZulu-Natal, Manguzi Forest Reserve, 13.XII.2010, J.G.H. Londt, NMSA. TANZANIA: 1♂, Singida, 1.XII.2008, G. Goergen, IITA; 1♀, Songea-Kyela, 21.XI.2008, G. Goergen, IITA; 1♀, Tunduru, 19.XI.2008, G. Goergen, IITA. TOGO: 1♂, Plateaux, Dzogbégan, monastery, 25.I.2016, K. Jordaens, RMCA; Kloto forest, 2♂ 1♀, January 2004, G. Goergen, IITA; 1♂, March 2004, G. Goergen, IITA; 1♂, April 2004, G. Goergen, IITA; 1♂, February 2005, G. Goergen, IITA; 1♀, November 2005, G. Goergen, IITA; 1♂, January 2016; G. Goergen, RMCA; May 2016, G. Goergen, 2♂, RMCA; 2♂, IITA; 1♂, December 2017, G. Goergen, RMCA; 2♀, May 2018, G. Goergen, RMCA; 1♂, February 2020, G. Goergen, RMCA; 1♀, March 2020, G. Goergen, RMCA; 6♂ 2♀, March-April 2020, G. Goergen, RMCA; 1♂, December 2020, G. Goergen, IITA; 2♂ 1♀, February 2021, G. Goergen, RMCA; 3♂ 3♀, March 2021, G. Goergen, RMCA. UGANDA: 1♀, Bundibugyo, 20.VII.2004, G. Goergen, IITA. ZIMBABWE: N. Vumba, 1♂, 10.XI.1963, D. Cookson, NMSA; 1♀, 13.V.1965, D. Cookson, NMSA.

Description

Body length: 12.7-15.9 mm. Wing length: 8.7-11.0 mm.

Male

Head (Figures 7-8). Eye with short pale orange-brown to pale yellow pile, towards posterior margin gradually shortening but present throughout; holoptic, eye contiguity about twice the length of the ocellar triangle or less. Frons protruding, in lateral view extending as far as facial tubercle; ground colour dark brown to black; area dorsal of antennae mainly slightly shiny, with long pale brown and black pile; with weak pale brown pollinosity, at eye margins denser pollinose. Ocellar triangle black, with short black pile; anterior part of ocellar triangle area with silvery pollinosity; with short pale brown pile or bare. Face ground colour brown to dark brown; with brown pollinosity, at eye margins denser pollinose, facial tubercle sometimes non-pollinose; with dispersed pale yellow pile along dorsolateral margins, otherwise bare; facial tubercle round and strongly pronounced. Antennal segments orange-brown, postpedicel sometimes darker brown, orbicular, scape and pedicel with some black pile; arista bare, orange-brown basally, darker apically. Thorax (Figure 2). Scutum slightly shiny black, with long pale brown pile throughout, though along lateral margin intermixed with black pile, with brown pollinosity which near transverse suture is more greyish and along lateral and posterior margins more yellowish; postpronotum yellow. Scutellum yellow, anteromedially slightly darker, with long pale yellow pile, anterior third sometimes with darker pale brown pile, though anterior margin always with narrow band of pale pile. Ground colour of pleura (Figure 13) black, posterior anepisternum, katepisternum, anterior anepimeron, and katatergite with long pale yellow pile, otherwise bare, brown to pale yellow pollinose. Legs. Femora mainly yellow-brown to orange-brown, with darker brown maculae in posterior part, sometimes more extensively darkened, with short to long dense pale yellow to yellowish brown pile, ventrally short and black pile. Metafemur (Figure 14) thickened, in anterior view medial part about twice as broad as apex, ventrally dense black pilose in distal half, in addition to few dispersed long pale yellow hairs. Tibiae dark brown to orange-brown, with short black pile; metatibia (Figure 14) slightly curved and thicker than pro- and mesotibae; with medium length black pile, pile length subequal to width of tibia. Tarsal segments orange-brown, with short brownish pile. Wing (Figure 18). Largely hyaline, anterior part sometimes very slightly infuscated, most areas microtrichose. Well-developed stigmal cross-vein present between distal end of vein Sc and middle of vein R¡. Cell r¡ closed with petiole, sometimes petiole strongly reduced. Vein R4+5 sinuate, without auxiliary vein. Abdomen (Figure 22). Partially shining dark brown to black, predominantly with dense short to medium length pale yellow to white pile producing a woolly appearance. Tergum 1 yellow to orange ground colour, with long white pale pile, white pollinose. Tergum 2 with a pair of rectangular yellow-orange maculae narrowly separated by thin black medial line, sometimes touching and forming a fascia, along posterior margin narrowly orange; posterior margin, up to one-fourth in some specimens, with black pile. Anterior fourth to third of tergum 3 yellow-orange, sometimes area much reduced, posteriorly sometimes also narrowly yellow-orange medially, posterior fourth to two-third with short black pile. Tergum 4 with short to medium length pale yellow pile in at least anterior half, at most the posterior half with black pile; partially grey to brown pollinose. Sterna predominantly black, anterior 1-3 partially yellow-orange, with very long, dispersed pale yellow pile sometimes with short black pile intermixed.

Female

As male except for the following characters: eyes widely dichoptic, frons slightly shiny dark brown to black, grey pollinose except the brown dorsal third.

Distribution

Benin, Burundi, Côte d'Ivoire, Democratic Republic of Congo, Equatorial Guinea (Bioko Is.), Guinea-Bissau, Malawi, Republic of the Congo, Rwanda, Senegal, South Africa, Tanzania, Togo, Uganda and Zimbabwe.

Eristalis tenax (Linnaeus, 1758)

Musca tenax Linnaeus, 1758: 591.

An overview of literature references is given in El Hawagry and Gilbert (2019)

(Figures 3, 9-10, 15-16, 19, 23)

Differential diagnosis

This species can be differentiated from E. pallidibasis and E. plumipes by the slender metafemur (thicker in E. pallidibasis and E. plumipes), the presence of long pile on anterior anepisternum (bare in E. pallidibasis and E. plumipes), the pilosity in the central part of the eyes with longitudinal stripes of denser and longer pilosity (pilosity evenly dispersed and of similar length in E. pallidibasis and E. plumipes), and the black colour of the first abdominal tergum (yellow to orange in E. pallidibasis and E. plumipes).

Material examined

CABO VERDE: S. Nicolau, 1♂, November 1898, L. Fea, MCSNG; 1♀, December 1898, L. Fea, MCSNG. LA REUNION: Bras-des-Calumets, 2♂, 29.X-5.XI.2015, K. Jordaens, RMCA; 2♂ 1♀, 2 November 2015, K. Jordaens, RMCA; 1♀, Cirque de Cilaos: Mare Sèche, 11.XI.2015, K. Jordaens, RMCA; Forêt Départementodomaniale de Bébour: Bras Cabot: river, 1♂ 1♀, 1.XI.2015, K. Jordaens, RMCA; 1♀, Forêt Départemento-domaniale de Bébour: Bras Cabot: river, 4.XI.2015, K. Jordaens, RMCA; 1♂, La Plaine des Cafres: la Grande Montée: Gros Piton Rond, 17.X.2015, K. Jordaens, RMCA; 1♂, La Plaine des Cafres: la Petite Plaine: Bras Noir: river, 17.X.2015, K. Jordaens, RMCA;La Plaine des Cafres: Piton Doret, farm W of, 1♂ 1♀, 17.X.2015, K. Jordaens, RMCA; 7♂ 2♀, 2.XI.2015, K. Jordaens, RMCA; 1♀, Nez de Boeuf, 2.XI.2015, K. Jordaens, RMCA. LESOTHO: 1♂, Maseru District, Blue Mounatin Pass Makhaleng Valley, 12.I.1963, B.R. and P.J. Stuckenberg, NMSA; 5♂ 4♀, Leribe District, Motebong Lodge, 10.XII.2021, J. Midgley and B. Muller, NMSA; 1♂ 1♀, Maseru District, Roma Mission, 4.I.1963, B.R. and P.J. Stuckenberg; NMSA; 1♂, Tséhlanyane National Park, near Butha-Buthe, 21.III.2008, G.B.P. Davies, NMSA. SOUTH AFRICA: 1♂, Western Cape, 10km N of Tulbach, 27.IX.1979, J.G.H. Londt, NMSA; 1♀, Northern Cape, 11 mi. E. Port Nolloth, 6.IX.1972, M.E. and B.J. Irwin, NMSA; 1♂, KwaZulu-Natal, 11km SE of Eston, 27.II.1988, A. Mackenzie, NMSA; 1♀, Western Cape, 1km N of Laaiplek, 6.IX.1989, J.G.H. Londt and P. Croeser, NMSA; 1♂ 1♀, Northern Cape, 1km W Nieuwoudtville, 4.XI.1991, J.G.H. Londt, NMSA; 1♂, Western Cape, 20km SW of Stellenbosch, 30.X.1991, J.G.H. Londt, NMSA; 1♂ 1♀, Western Cape, 28km E Veldrif, 15.X.1972, J.G. Rozen, R. McGinley and C. Thompson, AMNH; 2♂ 1♀, Western Cape, 2km S of Philadelphia, 29.VIII.1981, J.G.H. Londt, L.E. Schoeman and B.R. Stuckenberg, NMSA; 1♂ 1♀, Eastern Cape, 30km E Rhodes, Naudesnek Summit, 4.II.1991, Natal Museum Staff, NMSA; 1♀, KwaZulu-Natal, 32 Panorama Road, Hilton, 15.VIII.2020, J. Midgley, NMSA; 1♂, Northern Cape, 3km N of Calvinia, Kareedam Nature Reserve, 29.XI.1990, J.G.H. Londt and A.E. Whittington, NMSA; 1♂, Western Cape, 3km SE of Oudtshoorn, 9.XI.1986, J.G.H. Londt and C. Quickelberge, NMSA; 1♂ 1♀, Western Cape, 4km E of Stellenbosch, Jonkershoek Mountain area, 30.X.1991, J.G.H. Londt, NMSA; 1♂ 1♀, WesternCape, 4km SW of Clanwilliam, 28.VIII.1989, P. Croeser, B.R. Stuckenberg and J.G.H. Londt, NMSA, 1♂, Western Cape, 5km E of Wellington, on Bainskloof Pass, 27.IX.1979, J.G.H. Londt, NMSA; 1♂ 1♀, Western Cape, 5km E of Wellington, 31.X.1991, J.G.H. Londt, NMSA; 2♀, Eastern Cape, 5km ENE of Rhodes, 5.II.1992, Natal Museum Staff, NMSA; 1♂, Western Cape, 5km W of Villiersdorp, 26.IX.1979, J.G.H. Londt, NMSA; 1♂ 2♀, Eastern Cape, Bell River, at Rhodes, 5.II.1992, Natal Museum Staff, NMSA; 2♂, Free State, Bloemfontein, 1.X.2014, K. Jordaens and M. De Meyer, RMCA; 1♀, Free State, Bloemfontein, Franklin Game Reserve, Naval Hill, 19.XII.2008, A.H. Kirk-Spriggs, BMSA; 1♀, KwaZulu-Natal, Bulwer, Homerule, 8.II.1986, A.E. Whittington, NMSA; 2♂, Western Cape, Cape Town, 20.VIII.1917, A. Roberts, NMSA; 1♀, KwaZulu-Natal, Cathedral Peak Area, Forest Reserve, 4.IV.1977, J.G.H. Londt, NMSA; 4♀, KwaZulu-Natal, Cobham Nature Reserve, 16-18.X.2019, K. Jordaens, RMCA; 1♀, KwaZulu-Natal, Cobham Nature Reserve, 16.X.2019, J. Midgley, NMSA; 1♂, Eastern Cape, Coldstream, Tsistikama Area, 25.X.1964, B.R. and P.J. Stuckenberg, NMSA; 1♂, Western Cape, Du Toit Kloof, Paarl District (Dutoitskloofpas), 27.IX.1959, B.R. and P.J. Stuckenberg, NMSA; 1♀, Free State, Ficksburg, 15km NE, 27.III.1982, J.G.H. Londt and L.E. Schoeman, NMSA; 1♀, Eastern Cape, Gamtoos Valley Bush, Hankey Area, 5.XII.1967, B.R. and P.J. Stuckenberg, NMSA; 3♂, Western Cape, George, 9.II, H. Brauns, NMSA; Western Cape, 3♀, 18.I, H. Brauns, NMSA; 1♀, 2.III.1919, H. Brauns, NMSA; 1♂ 2♀, 20.I, H. Brauns, NMSA; 1♂, Free State, Golden Gate Nature Reserve, 27.III.1982, L.E. Schoeman and J.G.H. Londt, NMSA; 1♀, Western Cape, Gonnemanskraal, N of Jacobsbaai, 9.XI.2002, J.G.H. Londt, NMSA; 1♀, Western Cape, Good Hope Farm, 35km SW of Robertson, 21.X.2005, J.G.H. Londt, NMSA; 1♀, Eastern Cape, Grahamstown [=Makhanda], 17.XII.1952, B.R. Stuckenberg, NMSA; Eastern Cape, 1♀, 6.I.1953, B.R. Stuckenberg, NMSA; 1♀, 31.V.1969, J.G.H. Londt, NMSA; 1♀, Eastern Cape, 22.X.1969, J.G.H. Londt, NMSA; 3♂ 3♀, Eastern Cape, 12.II.1971, J.G.H. Londt, NMSA; 3♂, KwaZulu-Natal, Hiltara Park, 21.XII.2017, J. and B. Midgley, NMSA; 1♂, Eastern Cape, Hogsback, 18.I.1984, D.A. and C. Barraclough, NMSA; 1♀, Gauteng, Johannesburg, 28.2.1911, Gladstone, NMSA; 3♂ 1♀, 1926, R. Ellenberger, DMF; Gauteng, 1♂, 14.X.1951, H. Paterson, NMSA; 1♀, 11.IV.1952, F. Zumpt, NMSA; 1♀, 2.XII.1966, J.G.H. Londt, NMSA; 1♀, 27.XII.1970, J.G.H. Londt, NMSA; 1♀, 30.XII.1970, J.G.H. Londt, NMSA; 1♂, Western Cape, Karoo National Park, Beaufort West, 12.XI.1986, J.G.H. Londt and C. Quickelberge, NMSA; 1♀, KwaZulu-Natal, Khotso Horse Trail, near Underberg, 8.XII.2008, P. Reavell, NMSA; 1♀, Eastern Cape, Kite Site, 15.II.2021, T. Bellingan, NMSA; Eastern Cape, Kokstad, 1♀, 5.I.1973, A. Butler, NMSA; 2♀, 9.I.1973, A. Butler, NMSA; Western Cape, Kommetjie, 1♀, 14.X.1972, J.G. Rozen, R. McGinley and C. Thompson, AMNH; 1♀, 22.X.1972, J.G. Rozen, R. McGinley and C. Thompson, AMNH; 1♀, 12.X.1972, J.G. Rozen, R. McGinley and C. Thompson, AMNH; 1♂ 1♀, Western Cape, Kommetjie Hill, overlooking town, 13.XII.1988, J.G.H. Londt, NMSA; 1♂, Western Cape, Laaiplek, 9.X.1977, R.M. Miller, NMSA; 1♀, KwaZulu-Natal, Lion Bush, Fort Nottingham Road, 27.IV.1955, B.R. Stuckenberg, NMSA; Eastern Cape, Lundean's Nek, 1♀, 9.X.2019, K. Jordaens, RMCA; 2♂ 2♀, 8.X.2019, J. Midgley, NMSA; 1♂, Mpumalanga, Mariepskop National Park, 23-24.I.2017, K. Jordaens, RMCA; 1♂, Eastern Cape, Mcabalala, 13-14.X.2019, K. Jordaens, RMCA; 1♂, Western Cape, Muizenberg, 10km NW, 12.IX.1981, B.R. Stuckenberg, J.G.H. Londt and L.E. Schoeman, NMSA; 2♂, Eastern Cape, Naude's Nek: Tenahead Lodge, 10.II.2022, T. Bellingan, K. Jordaens and J. Midgley, NMSA; 1♀, Northern Cape, Nieuwoudtville Area, Calvinia District, 14.X.1964, B.R. and P.J. Stuckenberg, NMSA; 2♂, Western Cape, Outskirts of Ashton, 10.IX.1981, B.R. Stuckenberg, J.G.H. Londt and L.E. Schoeman, NMSA; 1♀, Outskirts of De Wet, 11.IX.1981, B.R. Stuckenberg, J.G.H. Londt and L.E. Schoeman, NMSA; 1♀, Western Cape, Paarl Mountain Nature Reserve, 26.IX.1993, J.G.H. Londt, NMSA; 1♀, Mpumalanga, Piet Retief [=eMkhondo], 15.III.1919, H. Brauns, NMSA; Eastern Cape, Port Elizabeth, 1♀, 11.XII.1941, G. Clark, NMSA; 1♀, 14.XII.1941, G. Clark, NMSA; Gauteng, Pretoria, 1♀, 20.VI.1906, C.J. Swierstra, NMSA; 1♂, 9.II.1915, A. Roberts, NMSA; 1♂, 2.I.1972, L. Vari, NMSA; 1♀, Western Cape, Rawsonville-Dwarsberg trout farm, 10-12.X.2017, K. Jordaens, MCA; 2♂ 1♀, Eastern Cape, Rhodes, 7.II.2022, T. Bellingan, J. Midgley and K. Jordaens, RMCA; 6♂ 5♀, Eastern Cape, Rhodes Area, 9.I.1979, J.G.H. Londt and B.R. Stuckenberg, NMSA; 5♂ 4♀, Eastern Cape, Rhodes Village area, 4.II.1992, Natal Museum Staff, NMSA; 2♀, Eastern Cape, Rhodes Village: Meadow near Firefly Cottage, 7.II.2022, T. Bellingan, K. Jordaens and J. Midgley, NMSA; 1♂, Eastern Cape, Rhodes Village: Walkerbouts Inn, 9.II.2022, T. Bellingan, K. Jordaens and J. Midgley, NMSA; 1♀, Northern Cape, Richmond, Service Station, 30.XI.1990, J.G.H. Londt and A.E. Whittington, NMSA; 1♀, Western Cape, Robertson, Vrolijkheid Nature Cons. Station, P. Meakin, NMSA; 1♂ 1♀, KwaZulu-Natal, Rosetta, Chrispin's Corner, 6.I.1991, A.E. Whittington, NMSA; 1♀, KwaZulu-Natal, Royal Natal National Park, 23.III.1991, J.G.H. Londt, NMSA; 1♂ 1♀, KwaZulu-Natal, Sani Pass Summit area, 25.II.2000, J.G.H. Londt, NMSA; 2♂ 2♀, KwaZulu-Natal, Silverdale, Nottingham Road, 11.IV.1978, NMSA; Western Cape, Stellenbosch, 1♂, 15.X.1916, H. Brauns, NMSA; 11♂ 3♀, 24.XI, H. Brauns, NMSA; 2♂ 1♀, 25.X, H. Brauns, NMSA; 1♂, 15.XII.1993, P. Reavell, NMSA; 1♀, Western Cape, Stellenbosch Suburb, 14.XII.1993, P. Reavell, NMSA; 1♂, Western Cape, Table Mountain, Cape Town, 21.II, NMSA; 1♀, Western Cape, Tremitri Ver Month, Caledon, 24.X, H. Brauns, NMSA; 1♂, KwaZulu-Natal, Umzimkulu, 11.I.1979, NMSA; 1♂, KwaZulu-Natal, Umzimkulu, 12.I.1979, NMSA; 1♀, KwaZulu-Natal, Umzimkulu, 13.I.1979, NMSA; KwaZulu-Natal, Underberg, 2♂, 14.IV.1981, A. van Bruggen, NMSA; 1♂, 16.IV.1981, A. van Bruggen, NMSA; 11♂ 14♀, Mpumalanga, Volksrust, 22.I, G. van Dam and A. Roberts, NMSA; 1♂, Western Cape, Wellington, 30km NE of Bainskloof Pass, 27.IX.1979, J.G.H. Londt, NMSA; Western Cape, Wilderness, 1♀, 21.I.1964, J. Taylor, NMSA; 1♀, 29.IX.1964, J. Taylor, NMSA; Eastern Cape, Willowmore, 1♂ 1♀, 20.X.1972, J.G. Rozen, R. McGinley and C. Thompson, AMNH; 1♂, 18.XI.1910, H. Brauns, NMSA; 1♀, 15.XI.1916, H. Brauns, NMSA; 1♀, 3.X.1921, H. Brauns, NMSA; 1♂, 1.X.1920, H. Brauns, NMSA; 1♀, [unknown locality], 8.I.1914, G.B. Longstaff, OXUM; 1♂, [unknown locality], 13.VII.1914, E.B. Poulton, OXUM. ST HELENA: 1♀, 1913, G. Babault, DMF; 1♀, 27.V.1963, A. Loveridge, RMCA; 2♀, 9.III.1965, A. Loveridge, RMCA; 1♀, 24.III.1965, A. Loveridge, RMCA; 1♀, 15-30.XI.1965, P. Basilewsky, P.L.G. Benoit and N. Leleup, RMCA; 1♀, 22.XI.1965, P. Basilewsky, P.L.G. Benoit and N. Leleup, RMCA; 1♂, 6.XII.1965, P. Basilewsky, P.L.G. Benoit and N. Leleup, RMCA; 1♀, 1-15.I.1966, P. Basilewsky, P.L.G. Benoit and N. Leleup, RMCA; 2♂, January 1966, P. Basilewsky, P.L.G. Benoit and N. Leleup, RMCA; 1♀, 12.X.1966, A. Loveridge, RMCA; 2♂ 2♀, 22-31.I.1967, Decelle, N. and J. Leleup, RMCA.

Note: The following description of E. tenax is not intended to re-describe the species, but is given to compare its morphology with that of E. pallidibasis and E. plumipes.

Description

Body length: 11.0-16.7 mm. Wing length: 9.5-13.5 mm.

Male

Head (Figures 9-10). Eye with short pale orange-brown pile, in central part with pair of longitudinal bands of denser and longer pilosity, occupying about one third of compound eye; posteriorly pilosity more disperse and in ventral half near occiput absent; holoptic, eye contiguity about equal to the length of the ocellar triangle. Frons protruding, in lateral view extending as far as facial tubercle, ground colour black, long pale yellow pilose, in shining part black pile, largely covered by yellow-grey pollinosity except area dorsal of antennae where shining black. Ocellar triangle black, with short to medium length black pile, anterior part of ocellar triangle area with silvery pollinosity and bare. Face produced ventrally, ground colour black, mainly shining black in particular along medial part, laterally near gena and ventrally near oral margin, other parts with contrasting dense yellow-grey pollinosity; with long pale yellow pile on pollinose parts, otherwise bare; facial tubercle weakly pronounced. Antennal segments black-brown to black; arista bare, orange-brown; postpedicel slightly longer than wide to orbicular. Thorax (Figure 3). Scutum slightly shiny black, with long pale yellow to pale brown pile, with brown to grey pollinosity. Scutellum yellow, with long pale yellow pile. Ground colour of pleura (Figure 15) black, anterior and posterior anepisternum, katepisternum, anterior anepimeron, katepimeron, and katatergite with long pale yellow to pale brown pile, otherwise bare, grey pollinose.

Legs. Femora mainly black, distal part narrowly yellow to orange-brown, with short to long dense pale yellow pile, though metafemur ventrally with black pile, especially in distal half. Metafemur (Figure 16) slender with medial part barely broader than apex in anterior view. Tibiae predominantly black to black-brown, basal part broadly yellow to orange-brown; mesotibia more extensively so, with short pale yellow pile; metatibia (Figure 16) curved and thicker than pro- and mesotibiae, more pale to brownish in basal and distal half, with short to medium length black pile which is always shorter than width of tibia. Tarsal segments orange-brown to black, with short brownish pile. Wing (Figure 19). Largely hyaline, anteriorly distinctly infuscated in basal and/or medial part, most areas microtrichose. Well-developed stigmal cross-vein present between distal end of vein Sc and middle of vein R¡. Cell r closed with distinct and long petiole. Vein R₄+₅ sinuate, without auxiliary vein. Abdomen (Figure 23). Mainly shining black. Tergum 1 black, with long white pile, weakly white pollinose. Tergum 2 with a pair of largely triangular shaped yellow to orange maculae, clearly separated by a broad line, along posterior margin narrowly orange, with predominantly short pale yellow pile. Tergum 3 black or with pair of orange maculae in anterior half, with short pale yellow pile. Tergum 4 black, with short to medium length pale yellow pile. Sterna predominantly black, anterior 1-2 sometimes partially yellow-orange, with very long, dispersed pale yellow pile.

Female

As male except for the following characters: eyes widely dichoptic, frons slightly shiny black, grey pollinose except the brown dorsal third, with intermixed pale yellow to pale brown, and black pile.

Distribution

Afrotropical: Cape Verde Is., Kenya, Lesotho, La Réunion Is., Saint Helena Is. and South Africa. Also recorded from Madagascar (Macquart 1842; Bezzi 1908). Non-Afrotropical: Cosmopolitan, known from all regions except the Antarctic (El-Hawagry and Gilbert 2019).

Comments

This species appears not to be indigenous to the Afrotropical region. Macquart (1842: 90) stated that in the Afrotropics this European species occurs outside its native range, more specifically from Madagascar and La Réunion Is. ('île de Bourbon'), without giving more details. Most records relate to island areas (Cape Verde Is., La Réunion Is., Saint Helena Is.) in addition to southern Africa. The record from Kenya is the northernmost occurrence of this species on the African continent. It could only be verified by an image of a single specimen at the National Museums of Kenya (Nairobi) but appears to be clearly representing a specimen of E. tenax. However, deducing from the label (without date), it appears that the specimen was collected several decades ago, and the current presence of this species needs confirmation. There is a single record of E. tenax from Tanzania on GBIF (https://www.gbif.org/occurrence/4065055951). The record is from a dataset of aquatic invertebrates, so is likely a larva. Given the poor knowledge of Eristalinae larvae in the Afrotropics, this is likely a misidentification. The record is based on an observation, so no specimen is available for confirmation. Three of the authors of the present paper have visited Tanzania multiple times in the last decade and have never observed or collected any E. tenax. Eristalis tenax can be clearly differentiated from the indigenous fauna as outlined in the key and diagnostic descriptions.

Eristalis convexifacies Macquart, 1850

Eristalis convexifacies Macquart, 1850: 438.

(Figure 4)

Material examined

Holotype: ♂ 'Cap Vert', Bigot Collection (NHMUK).

Description

Macquart (1850) provides a short diagnostic description in Latin of the male, followed by a slightly more extensive description in French, as follows:

'Niger. Abdomine incisuris flavis fasciisque ntidis. Fasie producta. Pedibus geniculis flavis.

Face avancée, convexe, verte, à duvet jaune; proéminence peu saillante. Front à duvet jaune. Antennes noires; style brièvement villeux. Yeux velus. Thorax noir, à reflets cuivreux et bandes de duvet jaunâtre; écusson jaune. Abdomen d'un noir mat; à incisions jaunes et bandes luisantes avant ces incisions. Pieds noirs; cuisses postérieures non renflées; genoux jaunes. Ailes assez claires; nervures normales'

An English translation, structured according to the redescription in this paper, reads thus as follows:

Head. Eyes pilose. Frons with yellow pile. Face advanced, convex, green, with yellow pile; facial tubercle not very prominent. Antennal segments black; arista shortly pilose.

Thorax. Black, with copper reflections; fasciae of yellowish pile. Scutellum yellow.

Legs. Black with apical margin of femora and basal margin of tibiae yellow. Metafemur not enlarged.

Wings. Largely hyaline; veins normal.

Abdomen. Dull black, with yellow incisions and shiny fasciae anterior of these incisions.

Distribution

Cape Verde or Senegal, see discussion in Claussen and Barkemeyer (1987) and below on exact location.

Comments

Eristalis convexifacies was described by Macquart (1850) from the 'Cap Vert' and included in his fourth supplement to the series 'Diptères exotiques'. While this supplement deals largely with a collection collected in Oceania and deposited in the Muséum national d'Histoire naturelle of Paris, additional material is included, among others, material purchased by M. Bigot. Eristalis convexifacies is from the latter collection. There is one badly damaged specimen (Figure 4) of E. convexifacies in the NHMUK collection. The latter carries a typical Macquart identification label identical to the Macquart labels shown in Thompson (1988) in addition to a donation label indicating it originates from the Bigot collection and thus appears to be the actual type specimen. The poor condition of the specimen does not allow a clear recognition of the species. The strongly sinuate vein R₄₊₅, the long petiole on cell r¡, the slender metafemur, and the short pilosity on the eyes places this species in Eristalis based on the generic characteristics. Because of its poor condition, the absence or presence of pilosity on the katepimeron (or any other pleuron) cannot be observed. However, the shape of the face (not prolonged ventrally), and the pilosity on the eyes (dispersed short pile, no distinct bands) excludes E. tenax. The latter is the only Eristalis species recorded from the Cape Verde Islands (Claussen and Barkemeyer 1987). The latter authors consider the 'Cap Vert' location in Macquart (1850) as doubtful to be referring to the Cape Verde Islands but consider this a possible reference to Cap Vert peninsula in Senegal.

Nomen dubium

For one species, Simoides trichopus, and listed under Eristalis we could neither trace type material nor other specimens identified under this name. This species was described by Bigot (1891) based on material collected by Ch. Alluaud in July-August 1886 at the 'territoire d'Assinie' (see Alluaud 1886), a coastal area nowadays part of Côte d'Ivoire and situated east of Abidjan. No specific locations are given. Bigot (1891) indicates in the original publication that the material is deposited in his collection. The collection of Bigot was initially purchased by G.H. Verrall and later passed on to J.E. Collin (Evenhuis 1997). Verrall made a manuscript inventory of the collection. The collection is nowadays partially in the Hope Entomological Collections of the University Museum, Oxford (UK) and partially in the Natural History Museum, London (NHMUK) (Thompson 1988; Pont 1995). Pont et al. (2024) indicates that in the manuscript inventory of Verrall he listed one damaged specimen of S. trichopus in his collection but that the holotype is not to be found in either of the above-mentioned collections. This was confirmed by the current curator at the University Museum of Oxford and by personal visits of the first and last author at NHMUK.

Eristalis trichopus (Bigot, 1891)

Simoides trichopus Bigot, 1891: 373.

Holotype (not examined): ♂ CÔTE d'IVOIRE, Assinie, July-August 1886, Ch. Alluaud, Bigot collection. Whereabouts unknown.

Description

Bigot provides a Latin (Bigot 1891: 373) and French (Bigot 1891: 374) description of a single male specimen as follows (French description only):

'Antennes noires à base rougeâtre ; face noire, couverte latéralement d'un épais duvet jaune pâle ; front, au-dessus des antennes, muni de poils noirs ; thorax, d'un noir brun, densément couvert latéralement, ainsi que sur lesflancs, d'une épaisse villosité jaunâtre ; écusson, cuillerons et balanciers d'un fauve jaunâtre pâle ; abdomen noir, avec des poils jaunes assez épais sur les côtés ; premier segment d'un noir assez luisant, deuxième avec deux grandes macules latérales, trigonales, fauves, troisième avec une large bande basilaire, fortement échancrée en arrière, de même couleur, quatrième avec une bande semblable plus étroite et plus pâle (les pieds antérieurs manquent et les intermédiaires sont détériorés) ; pieds intermédiaires avec les fémurs noirâtres, tibias un peu roussâtres, ainsi que les métatarses, fémurs postérieurs un peu renflés, noirâtres, longuement et assez densémentpourvus de poils jaunâtres, tibias roussâtres, avec des poils bruns ; ailes presque hyalines ; yeux nus.'

Furthermore, he indicates that the length is 16mm.

An English translation, structured according to the redescription in this paper, reads thus as follows:

Male

Head. Eye without pile. Frons, dorsal of antennae, with black pile. Face ground colour black, laterally with dense pale yellow pile. Antennal segments black with a reddish base.

Thorax. Scutum black-brown, with dense yellowish pile laterally. Scutellum pale fawny coloured. Pleura with dense yellowish pile. Calypter and halter pale fawny coloured.

Legs (prolegs missing and mid legs deteriorated). Mesofemur blackish, mesotibia partially or more russet coloured. Metafemur blackish, somewhat swollen, densely covered with long yellowish pile. Metatibia russet coloured, with brown pile. Metatarsal segments russet coloured.

Wing. Largely hyaline.

Abdomen. Black; laterally with fairly dense yellow pile. Tergum 1 rather shining black. Tergum 2 with a pair of large triangular tawny coloured maculae laterally. Tergum 3 with broad tawny coloured fascia anteriorly, strongly indented posteriorly. Tergum 4 with narrow and paler fascia in anterior part.

Distribution

Côte d'Ivoire (Bigot 1891), based on the type material. There are no other records for this species.

Comments

The description does not allow us to unambiguously place this species at generic level. The absence of pile on the eyes excludes the genus Eristalis. Mallota species as defined by De Meyer et al. (2024) is also largely excluded as representatives with bare eyes are either restricted to Madagascar (M. hirsuta Hull, 1941, and M. meromacrimima Hull, 1941) or have a distinct black macula on the wing (M. aperta (Bezzi, 1912)). The other characteristics given in the description (pair of paler coloured maculae on abdominal tergum 2, pale coloured fascia on abdominal tergum 3, metafemur thickened) correspond partially with Phytomia melas (Bezzi, 1912) but other characters (e.g., metafemur, pile on scutellum) do not. The only Senaspis with hyaline wing is S. pennata (Hervé-Bazin, 1914) but the abdominal markings are different. Some of the characteristics may also correspond to Eristalinus but there is no mention of the typical maculae or fasciae present on the eyes in this genus (even though both characters may disappear in older material). We therefore, consider Simoides trichopus to be a nomen dubium until comparative material from the type locality region can be obtained or the type material is traced.

 

DISCUSSION

The generic concept Eristalis has been used for a variety of species worldwide. The designation of Musca tenax as type species, allowed to clearly define and fix the generic concept as it was initially proposed by Latreille (1804) (Thompson 2003). This generic concept includes the character states of a strongly sinuate vein R₄+₅ and a petiolate cell r₁. Subsequent authors (Rondani 1857; Mik 1897; Hull 1925; Shiraki 1930; Kanervo 1938) recognised several subgroups but these were always based on a restricted biogeographic area (Thompson 2003). Only Hull (1949) provided a world review of all syrphid genera. He listed a number of recognised subcategories under Eristalis and provided a key to differentiate Eristalis from other eristaline genera but not to recognise the subgroups under Eristalis. Also, Afrotropical species listed previously under Eristalis represent a variety of species with different morphological features, several of which are now placed in other genera. Conversely, some species originally placed in other genera (Musca, Simoides) are now under Eristalis. Early reviews are given by Bezzi (1912, 1915). According to the latest generic key for Afrotropical Syrphidae (Ssymank et al. 2021) representatives of Eristalis belong to the group of eristalines characterised by:

Wing vein R₄₊₅ strongly sinuate, wing cell r₁ petiolate (differentiating it from Mallota, Mesembrius, Syrittosyrphus, Merodon), thorax with triangular part of anepimeron bare or with very short pile (differentiating it from Eristalinus s.l., which has long pile), and eyes pilose (differentiating it from Senaspis, Phytomia and Simoides). A differentiation is made between E. tenax (with katepimeron pilose) and the other Eristalis species (katepimeron bare). The latter are further differentiated from Meromacroides by the shape of the metafemur and wing markings and venation (see Ssymank et al. 2021 for details).

These differences are also apparent in the key to the groups of the subtribe Eristalina by Thompson (2003) where a differentiation is made between the Afrotropical Eristalis species (grouped under 'Eristalis' dasyops group, excluding E. tenax) and Meromacroides. According to Thompson (2003) the former group included E. apis, E. dasyops, E. plumipes, and E. pallidibasis. As such, it partially overlaps with the classification by Bezzi (1915). However, Eristalis dasyops is currently placed in the genus Mallota (De Meyer et al. 2024) based on the shared characteristics of the long pilose and dichoptic (in both sexes) eyes and wing cell r₁ which is not petiolate. The (sub)generic concepts within and among these eristaline groups need to be further revised, and need to include representatives of other Afrotropical (e.g., Syrittosyrphus Hull, 1944) and non-Afrotropical genera (e.g., Myathropa Rondani, 1845), as well as non-Afrotropical species of the genera Eristalis and Mallota.

As stated by De Meyer et al. (2024), until a comprehensive molecular phylogeny of the Afrotropical Eristalinae is available it is not appropriate to move the Afrotropical Eristalis species into other genera, despite the fact that they show morphological differences when compared to E. tenax and the generic concept.

Our study demonstrated that two species, E. pallidibasis and E. plumipes are widely distributed in the Afrotropics and co-occur in some places. Their biology is unknown currently so it is not possible to provide information on the biological criteria that may differentiate them. Eristalis tenax on the other hand is much more restricted in its distribution, with records mainly from southern Africa and some islands, but can be rather abundant in those places where it does occur. Given its known biology (larvae are known to survive in waterbodies rich in organic matter (Ssymank et al. 2021) one could expect it to occur more widely throughout the continent. The reason for its more restricted distribution is unknown.

 

ACKNOWLEDGEMENTS

We would like to thank the following curators, collection managers and researchers who made material available to us for study: C. Richenbacher, A. Pierwola and D. Grimaldi (AMNH), A.H. Kirk-Spriggs (ANHRT), B. Muller (BMSA), M. Tavano (MCSNG), N. Wyatt and D. Sivell (NHMUK), Z. Simmons and R. Douglas (OXUM), P. Limbourg and W. Deconinck (RBINS) and S. Cavaillès (SCPC). In addition, thanks to L. Njoroge for providing us with images of the E. tenax specimen housed at the National Museums of Kenya (Nairobi Kenya). This project was financed through the JRS Biodiversity Foundation projects 60512 and 60868 PINDIP (Pollinator Information Network for two-winged insects (Diptera); www.pindip.org), Belspo-NRF joint network project DIPTATEACH (Diptera Museum collections as a source for Taxonomic research and Teaching activities) and DIPoDIP (Diversity of Pollinating Diptera in South African biodiversity hotspots) which is financed by the Directorate General for Development Cooperation and Humanitarian Aid through the Framework agreement with RMCA.

 

AUTHOR CONTRIBUTIONS

MDM, KJ: conceptualisation; KJ, GG, TB, JM: collecting material; MDM, JM, KJ: analysing; GG: image preparation. All authors contributed to, and reviewed the manuscript.

 

ORCID IDS

M. De Meyer: https://orcid.org/0000-0003-0755-2898

G. Goergen: https://orcid.org/0000-0003-4496-0495

T. Bellingan: https://orcid.org/0000-0002-3064-1744

J. Midgley: https://orcid.org/0000-0003-1203-3750

K. Jordaens: https://orcid.org/0000-0003-4321-5944

 

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Correspondence:
K. Jordaens
Email: kurt.jordaens@africamuseum.be

Received: 14 October 2025
Accepted: 20 November 2025