Mesembrius chapini Curran, 1939

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

publication ID	https://dx.doi.org/10.3897/zookeys.1046.57052
publication LSID	lsid:zoobank.org:pub:66E61C4E-FAFE-45DE-9145-DB38199BDEC3
persistent identifier	https://treatment.plazi.org/id/7220A207-FAF4-5ACB-A7C8-3B7B13D2F214
treatment provided by	ZooKeys by Pensoft
scientific name	Mesembrius chapini Curran, 1939
status

Treatment

Mesembrius chapini Curran, 1939 Figs 8 View Figures 7, 8 , 31 View Figures 31, 32 , 51 View Figures 46–51 , 72 View Figures 70–74 , 88 View Figures 83–88 , 111 View Figures 107–112 , 130 View Figures 127–130 , 151 View Figures 151–154 , 169 View Figures 166–171 , 186 View Figures 185–188 , 201 View Figures 201–204 , 210 View Figures 205–216

Mesembrius chapini Curran, 1939: 10.

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

Differential diagnosis.

Mesembrius chapini males have a profemur with a thick and dense, golden apical pile brush. The metafemur is long and slender with some long, black thick pile in the ventral middle. The metatibia has a shallow anterior depression in the middle and a deeper depression on the ventral side of the distal end; the ventral side has a carina. The male is easily distinguished by the thick golden yellow to orange apical pile brush of the profemur and the series of minute, black spines in the ventroproximal section of the metafemur. Females have a frons which is black pilose on its entire length, except laterally. It can be distinguished from the female of M. sulcus sp. nov. and M. tarsatus by the yellow-brown to chocolate-brown tibiae (black in M. sulcus sp. nov. and M. tarsatus ). It differs from the female of M. rex and M. regulus by the very conspicuous black pile over the entire length of the protibia (absent in M. rex ; restricted to distal half in M. regulus ) and by the dark brown to black protarsus (yellow-brown to chocolate-brown in M. rex and M. regulus ). The legs are very dark, but especially the tibiae are yellow-brown to chocolate-brown. The protibia has conspicuous black pile over its entire length. Wing cell r1 is distinctly open.

Examined material.

Mesembrius chapini Curran: Holotype, male, " Mesembrius // Mesembrius chapini // ♂ // Holotype // Curran " " Lukolela // left bank // Congo R. 1°5 ’S/7.I.1931” " J.P. Chapin // Ac. 31300" [AMNH]. Type studied from picture on the website.

Other material

Benin • 2♂♂ ; Ahozon ; date unknown; G. Goergen leg.; IITA • 3♂♂ 2♀♀; Calavi ; Apr 2014; G. Goergen leg.; IITA • 1♀; Cotonou ; 16-18 Jan 2016; G. Goergen leg.; IITA • 1♂ 1♀; Cotonou ; 1 Nov 2013; G. Goergen and K. Jordaens leg.; KMMA • 1♂; Cotonou ; 28 Jan 2016; K. Jordaens leg.; KMMA • 1♂; Dangbo ; 13 Jun 2015; G. Goergen leg.; KMMA • 2♂♂; Lokossa ; Nov 2005; G. Goergen leg.; IITA • 1♂; Niaouli ; 15 Jan 1998; G. Goergen leg.; IITA • 2♂♂ 1♀; Pahou ; 11 Jan 2014; G. Goergen leg.; IITA • 2♀♀; Porto Novo ; 28 Nov 2002; G. Goergen leg.; IITA • 1♂; Porto Novo ; Oct 2004; G. Goergen leg.; IITA • 1♂; Porto Novo ; 27 Jan 2016; G. Goergen leg.; IITA • 1♂; Porto Novo ; Jan 2016; K. Jordaens and G. Goergen leg.; KMMA • 2♂♂; 5♀♀; Porto Novo ; 20 Jan 2018; G. Goergen leg.; IITA • 1♂ 12♀♀; Porto Novo ; 27 Jan 2016; K. Jordaens and G. Goergen leg.; KMMA • 1♂ 1♀; Porto Novo ; 27 Jan 2016; K. Jordaens and G. Goergen leg.; IITA • 5♂♂ 8♀♀; Porto Novo ; 7 Mar 2018; G. Goergen & K. Jordaens leg.; KMMA • 4♂♂; Porto Novo ; date unknown; K. Jordaens leg.; KMMA . Democratic Republic of the Congo • 1♀ ; Tshopo, Basoko ; Oct 1948; P.L.G. Benoit leg.; KMMA • 1♂ 1♀; Equateur, Eala ; Jul 1936; J. Ghesquière leg.; KMMA ; 1♂; Equateur, Eala ; Mar 1936; J. Ghesquière leg.; RMNH • 1♂; Equateur, Eala ; 5 Apr 1935; J. Ghesquière leg.; RMNH • 1♂; Equateur, Eala ; Sep 1935; J. Ghesquière leg.; RMNH • 1♀; Equateur, Eala ; Jan 1936; J. Ghesquière leg.; RMNH • 2♂♂ 2♀♀; Equateur, Eala ; Feb 1936; J. Ghesquière leg.; RMNH • 5♂♂ 1♀; Equateur, Eala ; Mar 1936; J. Ghesquière leg.; RMNH • 1♀; Equateur, Eala ; Sep 1936; J. Ghesquière leg.; RMNH • 1♀; Equateur, Eala ; 28 Sep 1936; J. Ghesquière leg.; RMNH • 1♂ 2♀♀; Equateur, Eala ; Dec 1936; J. Ghesquière leg.; RMNH • 1♂; Equateur, Eala ; 25 Jul 1935; J. Ghesquière leg.; KBIN • 2♂♂ 1♀; Equateur, Eala ; Aug 1935; J. Ghesquière leg.; KBIN • 1♂; Equateur, Eala ; Sep 1935; J. Ghesquière leg.; KBIN • 1♀; Equateur, Eala ; Dec 1935; J. Ghesquière leg.; KBIN • 1♀; Léopoldville [= Kinshasa]; 1 Jun 1915; Lang and Chapin leg.; KMMA . Nigeria • 1♂ ; Ibadan, IITA Station ; 18 Nov 2004; G. Goergen leg.; IITA .

Re-description male

(Fig. 8 View Figures 7, 8 ). Body length: 14.0-17.2 mm. Wing length: 10.2-11.3 mm.

Head (Fig. 51 View Figures 46–51 ). Eyes bare; holoptic, eye contiguity almost as long as length of ocellar triangle. Face white with dark medial vitta; white pilose; white pollinose. Vertical triangle black; black pilose; yellow pollinose on ventral half. Distance between lateral ocellus and eye margin 1/2 width of ocellus. Frontal triangle short; yellow-white; with some long, black pile; yellow pollinose. Frontal prominence shiny black with orange-brown apex. Occiput yellow; yellow pilose; with some shorter and thicker black pile near eye margin; yellow and white pollinose. Antenna, scape and pedicel reddish-brown; postpedicel black; antennal arista reddish-brown.

Thorax. Scutum black with dorsally a pair of well-demarcated yellow vittae which are largely connected posteriorly. Scutum with faint lateral vitta; yellow and black pilose. Scutellum uniformly yellow-brown; with long yellow and shorter black pile.

Legs. All legs chocolate-brown; tarsi chocolate-brown. Proleg (Fig. 151 View Figures 151–154 ): Femur dorsoventrally flattened; posterodorsal side with sparse, long black and yellow pile in proximal half; with apical pile brush of long, dense and curved yellow thick pile, this yellow pile is longer in the distal 1/3 and is interspersed with equally long black pile; ventrally with long, black pile. Basitarsus without tuft of orange or black pile posteriorly. Mesoleg: Femur with long, yellow pile on proximal 2/3 and long black pile on distal 1/3. Tibia and tarsi black pilose. Metaleg (Fig. 186 View Figures 185–188 ): Femur long and thin, slightly curved pile; pile on dorsal and anterior side inconspicuous, except for some long, black pile at anterior distal end; patch of long yellow pile on proximal part; with row of very short and thick black spines on ventral distal half; with 2-5 very long, thick black pile in ventral middle; posteriorly with loose, long yellow and black pile which becomes denser at distal end. Tibia with long, black pile, especially in distal 2/3; anteriorly with shallow excavation in the middle; posteriorly with deep and broad bare excavation in proximal 1/3. Tarsi black pilose dorsally, orange pilose ventrally.

Wing (Fig. 130 View Figures 127–130 ). Entire wing dark, uniformly dense microtrichose.

Abdomen (Fig. 88 View Figures 83–88 ). Tergite II with pair of very large, yellow rounded maculae; black markings hourglass-shaped; anterior and posterior black markings equal in size marking, but posterior black marking with stronger white pollinosity; yellow and black pilose, but black pile more conspicuous in posterior half of tergite and somewhat denser in posterolateral corners. Tergite III and IV with broad yellow fascia; black markings on posterior half vague because of white pollinosity, but more pronounced in medial part; black and yellow pilose, but black pile rare in anterior 1/4.

Genitalia (Fig. 210 View Figures 205–216 ). Epandrium: Dorsal lobe of surstylus short, broadly rounded; with short black spines on almost entire surface. Ventral lobe of surstylus straight; bare.

Description female

(Fig. 31 View Figures 31, 32 ). Body length: 13.3-16.3 mm. Wing length: 10.2-11.0 mm.

Head (Fig. 72 View Figures 70–74 ). Eye bare; dichoptic. Face yellow-orange with dark medial vitta; white pilose; white pollinose. Frons black; black pilose in dorsal half, black and yellow pilose on ventral half; weakly white pollinose. Distance between lateral ocellus and eye margin approx. width of ocellus. Occiput black; yellow pilose, with some black pile near eye margin; yellow-white pollinose. Frontal prominence shiny black, distal end orange-brown; scape and pedicel orange-brown; postpedicel black; antennal arista reddish-brown.

Thorax. Scutum dark brown to black with dorsolateral a pair of vague, grey pollinose vittae which are connected posteriorly; grey pollinose lateral vitta very vague; yellow pilose with some black pile interspersed. Scutellum yellow-orange; yellow pilose with very sparse, shorter black pile interspersed.

Legs (Figs 169 View Figures 166–171 , 201 View Figures 201–204 ). All femora black, except for extreme distal ends which are orange-brown; yellow pilose. All tibia orange-brown, most distal tarsomere darkened; yellow and black pilose dorsally, yellow pilose ventrally. All tarsi orange-brown; black pilose, except for protarsus which is yellow-orange pilose ventrally.

Wing. Entire wing uniformly dense microtrichose.

Abdomen (Fig. 111 View Figures 107–112 ). Tergite II with a pair of large, orange, rounded maculae; yellow pilose, with dense short thick black pile on posterior black marking. Tergite III with orange fascia in anterior half and black marking in posterior half; yellow pilose with dense short thick black pile on posterior black marking. Tergite IV with narrow orange fascia; yellow-orange pillose. Tergite V black; yellow pilose.

Distribution.

Benin, Democratic Republic of the Congo and Nigeria.

Comments.

The female of the species was hitherto unknown. The male cannot be confused with any other species.