Mesembrius caffer (Loew, 1858)

Jordaens, Kurt, Goergen, Georg, Skevington, Jeffrey H., Kelso, Scott & Meyer, Marc De, 2021, Revision of the Afrotropical species of the hover fly genus Mesembrius Rondani (Diptera, Syrphidae) using morphological and molecular data, ZooKeys 1046, pp. 1-141 : 1

Mesembrius caffer (Loew, 1858) Figs 1 , 4 , 5-6 , 27-28 , 29 , 47-49 , 84-86 , 107-109 , 128 , 175 , 178 , 182 , 195 , 196 , 206-208

Helophilus caffer Loew, 1858: 380.

Helophilus caffer - Loew (1860): 384 - Karsch (1888): 381 - Hervé-Bazin (1914a): 297.

Helophilus (Tubifera) caffer - Hervé-Bazin (1914b): 103.

Tubifera caffra - Kertész (1910): 250.

Mesembrius caffer - Smith and Vockeroth (1980): 504.

Mesembrius mediopectinatus Szilády, 1942: 97. Syn. by Smith and Vockeroth (1980): 504.

Mesembrius ctenifera Hull, 1941: 333. syn. nov.

Mesembrius ctenifera - Keiser (1971): 261.

Mesembrius ctenifer - Smith and Vockeroth (1980): 504.

Differential diagnosis.

Mesembrius caffer males lack an apical pile brush on the profemur and have an unmodified metatibia. The metafemur is entirely covered with long, thin yellow pile, but lacks pile in the anteroventral and ventral proximal 1/4. The posteroventral proximal 1/4 has a comb of long yellow or black pile and the remainder of the posteroventral side has a comb of shorter, black pile. The maculae on tergite II are very large and rounded so that black markings have an hourglass shape; the posterior black marking is narrower than the anterior black marking. It can be distinguished from any other male by the bare anteroventral proximal area of the metafemur and the thick comb of yellow or black pile on the proximal end posteroventrally. Females have a frons which is pale pilose on the ventral half. Females of the spined morph (see description below) differ from females of all other species with pale pile on the ventral half of the frons (except from M. capensis ) in tergite II which has a yellow fascia (a pair of yellow maculae in other species). It differs from the female of M. capensis in the mesotibia which has conspicuous black pile in the ventral distal half (inconspicuous in M. capensis ) and the absence of thick, black spines at the distal ventral end (present in M. capensis ). Females of the nominal morph have a pair of yellow maculae on tergite II (fascia in the spined morph of M. caffer and in M. capensis ). Pro- and mesofemur are dark brown to black (yellow-brown in M. senegalensis ), the metafemur lacks a ventral medial swelling (present in M. minor ), the face is not markedly produced downwards (produced downwards in M. vockerothi sp. nov.) and the mesofemur has very sparse and short black pile on the distal end ventrally (long black pile in M. strigilatus ).

Examined material.

Helophilus caffer Loew: Lectotype (hereby designated), male, " Helophilus // Helophilus caffer // ♂ " “206” “207” "Loan // 575/99" "NHRS-BYWS // 000002618" [NRMS]. Helophilus caffer Loew: Paralectotype, female, " Helophilus // Helophilus caffer // ♀ " “206” "Loan // 575/99" "NHRS-BYWS // 000002617" [NRMS] .

Mesembrius ctenifera Hull: Holotype, male, " Mesembrius // Mesembrius ctenifera // Hull n. sp." "TYPE 6596 // Mesembrius // Mesembrius ctenifera // F.M. Hull " " Oriental forest // Fanovana Dist. // Fianarantsoa // Madagascar " "1-V, 1937. // (C. Lamberton)" [ANSP].

Mesembrius ctenifera Hull: Allotype, female, " Allotype ♀ // Mesembrius // Mesembrius ctenifera // F.M. Hull " " Oriental forest // Fanovana, Dist. // Fianarantsoa // Madagascar " [ANSP].

Other material

(nominal morph; see below). Burundi • 1♀ ; Bujumbura; 20 Feb 2017; G. Goergen leg.; IITA . Cameroon • 1♀ ; Maroua, Meskina ; 23 May 2018; M. Azo’o Ela leg.; MAPC . Democratic Republic of the Congo • 1♂ ,? Adu ; 8 Apr 1955; collector unknown; KMMA • 1♀ ; Coquilhatville [= Mbandaka], Bamania , Equateur; 21 Jul 1924; J. Bequaert leg.; KMMA • 1♂ ; Bambesa, Bas-Uélé; Dec 1933; H.J Brédo leg.; KMMA • 1♀ ; Barumbu, Léopoldville [= Kinshasa]; 15 Oct 1910; Dr. Bequaert leg.; KMMA • 1♀ ; Boma ; 15 Jul 1920; H. Schouteden leg.; KMMA • 1♀ ; Bondo, Bas-Uélé; J.J. Rodhain leg.; KMMA • 1♂ ; Bukama, Haut-Lomami ; 28 Mar 1911; J. Bequaert leg.; KMMA • 1♀ ; Bukama, Haut-Lomami ; 24 May 1911; J. Bequaert leg.; KMMA • 1♀ ; Bunia, Ituri ; 1938; P. Lefèvre leg.; KMMA • 3♂♂ 3♀♀ ; Faradje, Haut-Uélé; Nov 1912; Lang and Chapin leg.; KMMA • 4♂♂ ; Garamba, Haut-Uélé; Jun-Jul 1912; Lang and Chapin leg.; KMMA • 2♀♀ ; Kalemie ; 1-20 Jan 1919; R. Mayné leg.; KMMA • 1♂ ; Kasenyi, Lac Albert, Ituri ; 15 May 1935; H.J. Brédo leg.; KMMA • 1♀ ; Kasongo , Maniema; date unknown; Dr. Pons leg.; KMMA • 1♂ ; Kasonsero, Ituri ; 17 Jul 1914, J. Bequaert; KMMA • 1♂ 1♀ ; Stanleyville [= Kisangani], Tshopo ; Mar 1915; Lang and Chapin leg.; KMMA • 1♂ ; Komi, Sankuru ; May 1930; J. Ghesquière leg.; KMMA • 1♂ ; N’Gwese, Lac Kivu; date unknown; Carlier leg.; KMMA • 1♂ ; Elisabethville [= Lubumbashi], Haut-Katanga ; 3 Jun 1920; M. Bequaert leg.; KMMA • 1♀ ; Elisabethville [= Lubumbashi], Haut-Katanga ; Dec 1925; Van Sackeghem leg.; KMMA; 1♂ ; Elisabethville [= Lubumbashi], Haut-Katanga ; Jan1933; M. Bequaert leg.; RMNH • 1♀ ; Elisabethville [= Lubumbashi], Haut-Katanga ; 16 Nov 1921; M. Bequaert leg.; RMNH • 1♀ ; Elisabethville [= Lubumbashi], Haut-Katanga ; 9 May 1920; M. Bequaert leg.; RMNH • 1♂ ; Faradje, Ituri ; 11 Apr 1930; A. Collart leg.; KMMA • 1♀ ; Malima ; 14 Oct 1910; J. Bequaert leg.; KMMA • 1♀ ; Mayumbe, Luki ; 1924; L. Pieters leg.; KMMA • 1♀ ; Nyangwe , Maniema; 13 Dec 1910; Dr. Bequaert leg.; KMMA • 1♀ ; Nyangwe , Maniema; 19 Nov 1910; Dr. Bequaert leg.; KMMA • 1♀ ; Nyangwe , Maniema; 12 Nov 1910; J. Bequaert leg.; KMMA • 1♂ 1♀ ; Nyangwe, Maniema; Apr-May 1918; R. Mayné leg.; KMMA • 1♂ 1♀ , Apr-May 1918, R. Mayné leg.; RMNH • 1♀ ; Ubundu, Tshopo ; 21 Oct 1910; J. Bequaert leg.; KMMA • 1♂ ; Wombali, Mai-Ndombe ; Jul 1913, P. Vanderijst leg.; KMMA • 1♀ ; unknown locality; 14 Dec 1951; H. De Saeger leg.; KMMA. • 1♂ 1♀; 4 Jan 1951; H. De Saeger leg.; KMMA • 1♀; 30 Oct 1951; H. De Saeger leg.; KMMA. Ethiopia • 1♀ ; Koka ; 14 Jan 1968; J.W. Boyes leg.; CNC • 1♂ , N.W. shore of lake Zwai ; 3 Nov 1926; H. Scott leg.; NHMUK • 1♂ ; unknown locality; Nov 1911; R.J. Stordy leg.; NHMUK. Ghana • 1♂ ; Tamale ; Nov 1916; J.J. Simpson leg.; NHMUK . Kenya • 2♂♂ ; Kabete ; 24 May 1916; T.J. Anderson leg.; NHMUK • 4♂♂ ; Kanyamkago ; 13 Jun 1911; J. Pugh leg.; NHMUK • 1♂ ; Marsabit District, Rendili Njoro ; date unknown; C.A. Neave leg.; NHMUK • 1♂ ; Mbuyuni, Serengetti Plains ; 25 May 1916; T.J. Anderson leg.; NHMUK • 1♂ ; Voi ; 8-10 Feb 1912; S.A. Neave leg.; NHMUK • 1♀ ; Fisherman’s Camp, Naivasha ; 14 Mar 1993; M. De Meyer leg.; KMMA • 1♀ ; Chawia, near Wundanyi ; 25 Jan 2017; A. Ssymank leg.; ASPC • 1♀ ; Ologassai ; Apr 1986; J. Muhangani leg.; NMK • 1♀ ; Rift Valley ; 27-29 May 2013; R. Copeland leg.; ICIPE • 1♂ 1♀ ; Taita Hills ; 2017; A. Ssymank leg.; ASPC • 1♂ ; Turkana, Lothagam; Jul-Aug 1994; A.M. George leg.; NMK . Liberia • Bong 1♂ ; County, Suakoko ; 6 Feb 1988; G.G.M. Schulten leg.; RMNH . Madagascar • 1♀ ; Andasibe, Périnet; 29 Oct 2010; A. Ssymank leg.; ASPC • 3♂♂ ; Antananarivo; 28 Feb 2016; G. Goergen leg.; IITA • 2♂♂ 1♀ ; Antananarivo; 28 Feb 2016; G. Goergen leg.; KMMA • 1♂ ; Antananarivo; 8 Mar 2016; G. Goergen leg.; KMMA • 1♂ ; Antananarivo, Tsimbazaza ; 7 Feb 1968; J.W. Boyes leg.; CNC • 1♀ ; Antananarivo, Antananarivo, Tsimbazaza ; 6 Nov 1993; M. Hauser leg.; CAS • 1♂ ; Antananarivo, Antananarivo, Tsimbazaza ; 9 Oct 1993; M. Hauser leg.; CAS • 1♂ 1♀ ; Antananarivo, Tsimbazaza ; 16-22 Oct 1993; C. Kassebeer leg.; CNC • 1♂ 1♀ ; Antananarivo, Tsimbazaza ; 16-22 Oct 1993; C. Kassebeer leg.; NMK • 1♀ ; Fianarantsoa, Mahabo Mananivo, Ampitavananima forest ; 17-24 Mar 2007; M. Irwin, F. Parker and R. Harin’Hala leg.; CAS • 1♀ ; Tananarive ; 28-30 Apr 1968; K.M. Guichard leg.; NHMUK • 1♂ ; Tananarive ; 15 Oct 1957; F. Keiser leg.; NMB • 1♀ ; Tananarive ; 20 Oct 1957; F. Keiser leg.; NMB • 1♂ 1♀ ; Fianarantsoa; Ambodimanga ; 8 Aug 1958; F. Keiser leg.; NMB • 1♂ ; Ambongamaranitra ; 20 Jun 1958; F. Keiser leg.; NMB • 2♂♂ ; Tananarive ; 28-30 Apr 1968; K.M. Guichard leg.; NHMUK • 1♀ ; Tananarive ; 9 Sep 1980; J. Stelleman leg.; RMNH . Malawi • 1♂ ; Blantyre; 25 Apr 1910; J.E.S. Old. leg.; NHMUK • 2♂♂ ; Chiromo ; J.E.S. Old. leg.; NHMUK • 1♂ ; Cholo ; R.C. Wood leg.; NHMUK • 1♂ 2♀♀ ; Mulanje Mountain Forest Reserve ; 12-15 Nov 2016; K. Jordaens leg.; KMMA • 1♂ 6♀♀ ; Mulanje Mountain; Likhubula ; 12-14 Nov 2016; K. Jordaens leg.; KMMA • 3♂♂ ; N. Malawi; 1916; N.M. Leys leg.; NHMUK • 3♂♂ ; Ruo ; R.C. Wood leg.; NHMUK • 1♂ ; Chinteche ; H.S. Stannus leg.; NHMUK . Mozambique • 3♂♂ ; Sofala, Gorongosa Park ; 20-30 Apr 2015; M. Hauser and A. Runig leg.; CAS • 1♀ ; Luaba, lower Zambesi; Jun-Jul 1957; P.J. Usher and B. Stuckenberg leg.; CNC • 1♂ ; Luabo, lower Zambesi ; Apr 1958; P.J. Usher leg.; CNC • 1♂ ; E of Mount Mulanje ; 3-7 Oct 1913; S.A. Neave leg.; NHMUK . Nigeria • 1♀ ; Samaru ; 15-22 Jun 1972; P.H. Ward leg.; NHMUK • 1♀ ; Ibadan ; 28 May 1987; G.G.M. Schulten leg.; RMNH . Senegal • 1♂ ; Dakar; 14 Jan 1945; collector unknown; RMNH . South Africa • 1♀ ; Mariepskop, Mpumulanga ; 20-22 Jan 2017; K. Jordaens leg.; KMMA • 1♂ ; St. Lucia Bay, Natal ; 3 Nov 1959; D.J. Greathead leg.; NHMUK • 2♂♂ ; KwaZulu-Natal, Durban ; 1 Jul 1903; G. Burn leg.; NMSA • 1♂ ; Rinkarla ; date unkown; H. Junod leg.; NMSA . Tanzania • 2♂♂ ; Bondei ; Jan 1986; C.W. Schmidt leg.; MNB • 1♂ ; Zanzibar; Jan-Feb 1925; H.J. Snell leg.; NHMUK • 5♂♂ ; Zanzibar, Kizimbani ; 15 Jul 1985; G.G.M. Schulten leg.; RMNH • 5♂♂ 3♀♀ ; Kilanbeo ; 1 May 1971; W.S. Bos leg.; RMNH . Togo • 1♂ ; Kloto Forest ; Feb 2017; G. Goergen leg.; KMMA . Uganda • 2♂♂ ; Budongo, forest near Lake Albert ; Apr 1972; E.B. Babyetagara leg.; CNC • 1♂ ; Entebbe ; 3-4 Dec 1912; C.C. Gowdey leg.; NHMUK • 1♂ ; Entebbe ; 12-20 Jan 1912; S.A. Neave leg.; NHMUK • 2♂♂ ; Ibanda; 23-28 Dec 1972; H. Falke leg.; CNC • 1♂ ; Kigezi, Kayonza Forest ; Sep 1972; H. Falke leg.; CNC • 1♂ ; Kigezi, Kayonza Forest ; Dec 1972; H. Falke leg.; CNC • 1♀ ; Kitende ; 11 Sep 1927; J. Bequaert leg.; KMMA • 1♂ ; Masindi; 15-19 Dec 1911; S.A. Neave leg.; NHMUK • 1♂ ; locality unknown; Nov 1904; E.D.W. Greig leg.; NHMUK • 2♂♂ 4♀♀; Western Region, Kamwege District, Kibale Forest ; 8 Dec 2018; K. Jordaens; leg. KMMA • 3♂♂ 1♀ ; Mabamba swamps, Nkima lodge and surroundings; 16 Dec 2018; K. Jordaens leg.; KMMA . Zambia • 1♂ 1♀ ; Lusaka Province 8.5 km NW Katondwe ; 20 Apr 2016; M. Hauser leg.; CSCA . Zimbabwe • 1♀ ; Chishi Island, Bangweolo ; 26 Jun 1908; S.A. Neave leg.; OXUM • 1♂ ; Chinsali District, mid-Chambezi Valley ; 17 Apr 1908; S.A. Neave leg.; OXUM • 1♂ ; Mirongo ; 3 Apr 1908; S.A. Neave leg.; OXUM • 1♂ ; upper Luangwa Valley ; 29 Feb 1908; S.A. Neave leg.; OXUM • 1♂ ; upper Luangwa Valley ; 17 Mar 1908; S.A. Neave leg.; OXUM • 1♂ ; upper Luangwa Valley ; 20 Mar 1908; S.A. Neave leg.; OXUM • 1♂ ; upper Luangwa Valley ; 5-7 Mar 1908; S.A. Neave leg.; OXUM • 1♂ ; upper Luangwa Valley ; 23-24 Mar 1908; S.A. Neave leg.; OXUM .

(Morphotype with conspicuous spine on metatibia; see Variation, comments and discussion). “ARABIA” • 1♂; Abu; date unknown; C.G. Nurse leg.; NHMUK. Benin • 3♂♂ 3♀♀; Calavi; 8 Dec 2013; K. Jordaens and G. Goergen leg.; KMMA • 2♂♂ 3♀♀; 9 Dec 2013; K. Jordaens and G. Goergen leg; KMMA • 1♀; Calavi; Jan 2014; G. Goergen leg.; KMMA • 1 M; Calavi; Mar 2000; G. Goergen leg.; IITA • 1♂; Calavi; 17 Jul 2015; G. Goergen leg.; IITA • 1♂; Calavi; Oct 2015; G. Goergen leg.; IITA • 1♂; Cotonou; Dec 2003; G. Goergen leg.; IITA • 1♂ 2♀♀; Cotonou; 14 Dec 2013; K. Jordaens and G. Goergen leg.; KMMA • 4♀♀; Cotonou; 28 Jan 2016; K. Jordaens and G. Goergen leg.; KMMA • 1♂; Cotonou; 1 May 1989; G.G.M. Schulten leg.; RMNH • 1♂; Lama Forest ; 23 Jan 1995; G. Goergen leg.; IITA • 1♂; Lama Forest ; 26 Jul 1995; G. Goergen leg.; IITA • 2♀♀; Lama Forest ; 23 Jun 1995; G. Goergen leg.; IITA • 1♀; Niaouli; 2 Feb 2014; G. Goergen leg.; IITA • 1♂ 1♀; Pobè; 27 Jan 2016; G. Goergen leg.; IITA • 1♂ 1♀; Porto Novo; 27 Jan 2016; K. Jordaens and G. Goergen leg.; KMMA • 1♂; Sémé; 7 Feb 2016; G. Goergen leg.; KMMA • 1♂; Tanougou Waterfalls; Nov 2016; G. Goergen leg.; KMMA. Cameroon • 20♂ 20♀; Maroua, Meskina; 23 May 2018; M. Azo’o Ela leg.; MAPC • 1♂; Kribi, Lobe Falls ; 22 May 2006; A. Ssymank leg.; ASPC • 1♂; Victoria; 5-18 Nov 1975; W. Schacht leg.; RMNH. Ghana • 1♂; Japi; Nov 1915; J.J. Simpson leg.; NHMUK • 1♀; Tamale; Nov 1915; J.J. Simpson leg.; NHMUK • 9♂♂; Tamale; Nov 1916; J.J. Simpson leg.; NHMUK. Malawi • 1♀; Mulanje Mountain; 12-14 Dec 2016; K. Jordaens leg.; KMMA. Mali • 1♂ 2♀♀; Kogoni; Aug 1983; B. Sidibe leg.; NHMUK. Nigeria • 1♂; Samaru; 7-14 Jul 1970; P.H. Ward leg.; NHMUK. South Africa • 1♂; Dukuduku Forest Reserve ; 16-17 Jul 1981; J.G.H. Londt and K. Craddock leg.; NMSA. Senegal • 3♀♀; Dassilamé Sérère; 30 Nov 2011; S. Cavaillès leg.; SCPC • 1♀; Dindefelo; 5 Nov 2016; S. Cavaillès and R. Bou leg.; SCPC. Togo • 1♂; Marais d’Asrama; 8 Apr 2008; A. Ssymank leg.; MZH • 1♀; Kloto Forest ; Nov 2016; G. Goergen leg.; KMMA. Zambia • 1♂; Chilanga; 8 Sep 1913; R.C. Wood leg.; NHMUK • 1♂; Chilanga; 2 Jan 1914; R.C. Wood leg.; NHMUK .

(Morphotype with low spine on metatibia; see Variation, comments and discussion). Ghana • 9♂♂; Tamale ; Nov 1916; J.J. Simpson leg.; NHMUK. Nigeria • 1♂; Samaru; 7-14 Jul 1970; P.H. Ward leg.; NHMUK. Zambia • 1♂; Chilanga; 2 Jan 1914; R.C. Wood leg.; NHMUK .

Re-description of male

(Figs 4 - 6 ). Body length: 12.1-13.8 mm. Wing length: 8.2-10.0 mm.

Head (Figs 47-49 ). Eyes bare; slightly dichoptic, distance between eyes approx. the width of ocellus. Face white with dark medial vitta; white pollinose; white pilose. Frontal triangle white; white pilose; white pollinose. Vertical triangle black pilose in ventral half and at ocellar triangle, yellow pilose on vertex; yellow pollinose until just before anterior ocellus; distance between lateral ocellus and eye margin less than 1/2 width of ocellus. Frontal prominence shiny black. Occiput yellow; yellow and white pollinose; yellow pilose. Antenna black, antennal arista reddish-brown.

Thorax. Scutum black with only vague grey pollinose pair of vittae; yellow to rufous pilose. Scutellum uniformly yellow-brown; yellow pilose.

Legs. Proleg: Femur without apical pile brush; black; pile long, yellow, ventrally of equal size over entire length; without black pile. Tibia yellow in proximal half, black in distal half; with long, yellow pile. Tarsi dark brown; black pilose dorsally; orange pilose ventrally with some thick black pile, especially posteroventrally. Mesoleg (Figs 178 , 182 ): Femur dark brown to black; long yellow pilose, but short black pilose on dorsal distal 1/3. Tibia yellow, distally darkened; long yellow pilose, but with black pile interspersed in distal half. Tarsi dark brown; black pilose, with some yellow pile interspersed on basitarsus. Metaleg (Figs 195 , 196 ): Femur dark brown to black; bare in anteroventral and ventral proximal 1/4, posteroventral proximal 1/4 with thicker pile varying from entirely yellow (as in Fig. 195 : red arrow) to entirely black (as in Fig. 196 : red arrow); otherwise with long and thin yellow pile interspersed with shorter black pile ventrally. Tibia black; long yellow and black pilose; distal end variable: either with (as in Fig. 196 ; referred to as spined morph) or without (as in Fig. 195 ; referred to as nominal morph) a tooth-like projection ( “spine”) at the ventral distal end; unmodified, but with two shallow depressions on posterior side; long yellow pilose on anterior and dorsal side, black pilose on posterior and ventral side. Basitarsus long, as long as tarsomeres 2+3; dark brown; black pilose. Other tarsi dark brown; black pilose.

Wing (Fig. 128 ). Entire wing uniformly dense microtrichose.

Abdomen (Figs 84-86 ). Tergite II with a pair of very large, yellow rounded maculae; black marking hourglass-shaped; posterior black marking sometimes nearly absent (as in Fig. 85 ), if present, then narrower than anterior black marking; with short, stiff black setulae which do not extend to the lateral margins. Tergite III and IV with yellow fascia of variable size, often occupying almost the entire tergite, but sometimes strongly reduced; Tergite V strongly white pollinose, except for a black medial zone; with short, black stiff pile posteriorly which does not reach the lateral tergal sides.

Genitalia (Figs 206-208 ). Epandrium: Dorsal lobe of surstylus somewhat elongated, broadly rounded; with short, black spines on almost entire surface; dorsally long yellow pilose. Ventral lobe of surstylus straight without conspicuous pilosity.

Variation.

Males of this species are highly variable in their morphology. Some males (spined morph) have a tooth-like projection (spine) on the distal ventral end of the metatibia and the pile on the posterventral distal end of the metafemur is predominantly black. The nominal morph does not have a tooth-like projection (spine) on the distal ventral end of the metatibia and the pile on the posterventral distal end of the metafemur is predominantly yellow. We found 11 males from Zambia, Nigeria and Ghana with a very low spine on the distal ventral end of the metatibia; some of these had a broad, yellow fascia on tergite II, while others had a pair of large, yellow maculae on tergite II.

Re-description of female

(Figs 27 - 29 ). Body length: 12.5-15.0 mm. Wing length: 10.1-10.3 mm.

Head. Eyes bare; dichoptic. Face white with dark medial vitta; white pilose, white pollinose. Frons black on dorsal 2/5, yellow-white on ventral 3/5; black pilose on ocellar triangle and just ventrally of ocellar triangle, otherwise white pilose; pollinosity variable, but mostly strongly white pollinose on ventral 3/5. Distance between lateral ocellus and eye margin approx. width of ocellus. Occiput yellow-white; yellow-white pilose; yellow-white pollinose. Frontal prominence shiny black; antenna dark brown to black; antennal arista reddish-brown.

Thorax. Scutum dark brown with one pair of dorsolateral yellow pollinose vittae which are connected posteriorly and with lateral, yellow pollinose vitta; yellow pilose. Scutellum yellow-orange; yellow pilose.

Legs. Proleg: Femur black, distal end orange-brown; yellow pilose, short, black pilose on dorsal distal end. Tibia orange-brown in proximal 2/3, dark brown to black in distal 1/3; yellow pilose with thicker black pile interspersed on ventral side. Tarsi orange-brown; black pilose dorsally, yellow pilose ventrally. Mesoleg: Femur black; yellow-white pilose. Tibia orange-brown in proximal half, darkened in distal half; yellow-white pilose, with some shorter and thicker black pile ventrally, especially in distal half. Tarsi black; black pilose ventrally and dorsally, yellow pilose on posterior and anterior side. Metaleg: Femur black; yellow-white pilose with shorter and thicker black pile on ventral distal half. Tibia black; yellow-white pilose with some black pile interspersed ventrally. Tarsi black; short black pilose dorsally; densely yellow-orange pilose ventrally. In some specimens from Benin, the metafemur and metatibia is brown (but not as light as in M. senegalensis ) and without the interspersed black pile ventrally.

Wing. Entire wing uniformly microtrichose.

Abdomen (Figs 107-109 ). Tergite II with a pair of very large, rounded yellow-orange maculae (Figs 107 , 109 ; nominal morph) or with a yellow-orange fascia (Fig. 108 ; spined morph); yellow pilose on maculae, yellow and black pilose on hourglass-shaped black marking. Tergite III with broad (approx. 3/5 of tergal length in medial section), yellow-orange fascia, with posterior black marking; yellow pilose on fascia, predominantly black pilose on black marking and just anterior of black marking. Tergite IV with narrower yellow-orange fascia (approx. 1/3 of tergal length in medial section); yellow pilose on fascia, yellow and black pilose on black marking. Tergite V black; yellow pilose.

Variation.

The females also show substantial variation in their morphology. Females of the spined morph have a broad yellow-orange fascia on tergite II, whereas females of the nominal morph have one pair of large, yellow-orange maculae. Females are variable in the colour of the legs (varying from brown to black) and the abdominal pattern, with some females almost entirely lacking black abdominal markings. Especially the extent of the black markings is variable. In some specimens from Benin, the black markings were very vague so that specimens had an almost yellow-orange abdomen.

Distribution.

‘Arabia’, Benin, Burundi, Cameroon, Democratic Republic of the Congo, Ethiopia, Ghana, Kenya, Liberia, Madagascar, Malawi, Mali, Mozambique, Nigeria, Senegal, South Africa, Tanzania, Togo, Uganda, Zambia and Zimbabwe.

Comments.

The male syntype of M. caffer (Loew, 1858) (designated here as lectotype) and the male holotype of M. ctenifer Hull, 1941 are similar. According to Hull (1941), M. ctenifer is differentiated from any other Mesembrius species by the broad oval metabasitarsus and the black comb-like patch of black setae on the metatibia. Yet, these characters are shared with M. caffer , a species which was not mentioned in Hull (1941). DNA barcoding does not differentiate between M. caffer and presumed specimens of M. ctenifer (i.e. from Madagascar and identified as such by others). Male genital morphology neither differentiates between M. caffer and presumed M. ctenifer males (compare Fig. 206 with Fig. 207 ). Thus, we conclude that both are conspecific and that M. ctenifer Hull, 1941 is a junior synonym of M. caffer (Loew, 1858). According to Hull (1941), a female allotype is deposited at the ANSP, but the specimen could not be found.

Apart from the differences outlined above, males and females of both morphs are similar in morphology and male genitalia of both morphotypes are similar as well (compare Fig. 206 with Fig. 207 ). DNA barcoding does not differentiate both morphs (both morphotypes even share haplotypes). For the time being, we consider the morphological difference between the nominal and spined morph as intraspecific variation.

The species is widespread in the Afrotropical Region and has also been reported from “Arabia” (a male from Abu collected by C.G. Nurse; see examined material above). Arabia is the peninsular region, together with offshore islands, located in the extreme south-western corner of Asia. It is bounded by the Red Sea on the west and southwest, the Gulf of Aden on the south, the Arabian Sea on the south and southeast and the Gulf of Oman and the Persian Gulf on the east. It includes the modern coastal Arabian states of Yemen, Oman and the United Arab Emirates which, in a zoogeographical context, are part of the Afrotropical Region. However, we could not trace any reference of the collector of the specimen (C.G. Nurse) for the Afrotropical Region. Rather, C.G. Nurse has collected insects on Mount Abu, which is in Rajasthan (India) (see Rosa et al. 2020, for example) and it is thus likely that “Abu” refers to Mount Abu and not a place in Arabia (which are usually also given as binomens, e.g. Abu-Dhabi). The occurrence of the species on the Arabian Peninsula is thus doubtful. In case the specimen is not mislabelled, then it means that M. caffer also occurs in India.

Figures

Figures 1, 2. Mesembrius spp., live pictures 1 Mesembrius caffer (Loew) (♂), Uganda. Photo: Menno Reemer 2 Mesembrius tarsatus (Bigot) (♂), Uganda. Photo: Menno Reemer.

Figures 3, 4. Mesembrius spp., habitus, lateral view 3 M. arcuatus sp. nov. (♂) 4 M. caffer (Loew) (nominal morph) (♂).

Figures 5, 6. Mesembrius spp., habitus, lateral view 5 M. caffer (Loew) (spined morph) (♂) 6 M. ctenifer Hull syn. nov. (♀).

Figures 27, 28. Mesembrius spp., habitus, lateral view 27 M. caffer (Loew) (nominal morph) (♀) 28 M. caffer (Loew) (spined morph) (♀).

Figures 29, 30. Mesembrius spp., habitus, lateral view 29 M. ctenifer syn. nov. Hull (♀) 30 M. capensis (Macquart) (♀).

Figures 46 - 51. Mesembrius spp., head, frontal view 46 M. arcuatus sp. nov. (♂) 47 M. caffer (Loew) (nominal morph) (♂) 48 M. caffer (Loew) (spined morph) (♂) 49 M. ctenifer Hull syn. nov. (♂) 50 M. capensis (Macquart) (♂) 51 M. chapini Curran (♂).

Figures 83 - 88. Mesembrius spp., abdomen, dorsal view 83 M. arcuatus sp. nov. (♂) 84 M. caffer (Loew) (nominal morph) (♂) 85 M. caffer (Loew) (spined morph) (♂) 86 M. ctenifer Hull syn. nov. (♂) 87 M. capensis (Macquart) (♂) 88 M. chapini Curran (♂).

Figures 107 - 112. Mesembrius spp., abdomen, dorsal view 107 M. caffer (Loew) (nominal morph) (♀) 108 M. caffer (Loew) (spined morph) (♀) 109 M. ctenifer syn. nov. Hull (♀) 110 M. capensis (Macquart) (♀) 111 M. chapini Curran (♀) 112 M. cyanipennis (Bezzi) (♀).

Figures 127 - 130. Mesembrius spp., right wing 127 M. arcuatus sp. nov. (♂) 128 M. caffer (Loew) (nominal morph) (♂) 129 M. capensis (Macquart) (♂) 130 M. chapini Curran (♂).

Figures 172 - 176. Mesembrius spp., proleg, dorsal view 172 M. strigilatus (Bezzi) (♀) 173 M. minor (Bezzi) (♀) 174 M. senegalensis (Macquart) (♀) 175 M. caffer (Loew) (♀). Mesoleg, posterior view 176 M. sulcus sp. nov. (♂). Abbreviations: bt-basitarsus, fem-femur, tib-tibia.

Figures 177 - 180. Mesembrius spp., mesoleg, dorsal view 177 M. tibialis sp. nov. (♂) 178 M. caffer (Loew) (♂) 179 M. capensis (Macquart) (♂) 180 M. madagascariensis Keiser (♂). Abbreviations: bt-basitarsus, fem-femur, tib-tibia.

Figures 181 - 184. Mesembrius spp., mesoleg, dorsal view 181 M. senegalensis (Macquart) (♂) 182 M. caffer (Loew) (♂). Metaleg, posterior view 183 M. regulus (Hull) (♀) 184 M. rex Curran (♀). Abbreviations: bt-basitarsus, fem-femur, tib-tibia.

Figures 193 - 196. Mesembrius spp., metaleg, dorsal view 193 M. platytarsis Curran syn. nov. (♂) 194 M. simplicipes Curran (♂). Metaleg, anterior view 195 M. caffer (Loew) (nominal morph) (♂) 196 M. caffer (Loew) (spined morph) (♂). Abbreviations: bt-basitarsus, fem-femur, tib-tibia.

Figures 205 - 216. Mesembrius spp., male genitalia, lateral view 205 M. arcuatus sp. nov. 206 M. caffer (Loew) (nominal morph) 207 M. caffer (Loew) (spined morph) 208 M. ctenifer Hull syn. nov. 209 M. capensis (Macquart) 210 M. chapini Curran 211 M. copelandi sp. nov. 212 M. cyanipennis (Bezzi) 213 M. ingratus (Loew) 214 M. longipilosus sp. nov. 215 M. madagascariensis Keiser 216 M. minor (Bezzi).