Mesembrius nigriceps Curran, 1927

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/7691ECD7-2466-5122-8DCD-1D9BE08E00EC
treatment provided by	ZooKeys by Pensoft
scientific name	Mesembrius nigriceps Curran, 1927
status

Treatment

Mesembrius nigriceps Curran, 1927 View in CoL Figs 15 View Figures 15, 16 , 58 View Figures 58–63 , 95 View Figures 95–100 , 139 View Figures 139–142 , 192 View Figures 189–192 , 217 View Figures 217–228

Mesembrius nigriceps Curran, 1927: 63.

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

Differential diagnosis.

Mesembrius nigriceps males lack an apical pile brush on the profemur and have a metatibia which is curved, but less than in M. strigilatus . The face ground colour is black (white to yellow in M. strigilatus ). The metafemur is curved, has a patch of conspicuous black pile at the base and, perpendicular to this, a stretch of dense black pile on the ventroposterior side. The male is distinguished from any other species (except from M. strigilatus ) by the strongly curved metafemur and metatibia. It differs from M. strigilatus in the colour of the face (white to yellow in M. strigilatus ; black in M. nigriceps ), in the size and shape of the maculae on tergite II which are small and nearly triangular (large and rounded in M. strigilatus ) and by the broader black medial marking on tergite II (narrow in M Mesembrius strigilatus ). The female is unknown.

Examined material.

Mesembrius nigriceps Curran: Holotype, male, " Mesembrius // TYPE // Mesembrius nigriceps // Curran" "Taken from Bembex" "Stanleyville, Cgo. // 25°10'E, 0°30'N // III.1915 " "Lang & Chapin // Collectors" [AMNH]. Type studied from picture on website. GoogleMaps

Other material

Ghana • 1♂; Eastern Region, N of Kibi, Atewa Range Forest Reserve ; 21 Jun 2006; K.-D.B. Dijkstra leg.; MZH . Togo • 1♂; Kloto Forest ; Mar 2004; G. Goergen leg.; IITA .

Re-description male

(Fig. 15 View Figures 15, 16 ). Body length: 11.0 mm. Wing length: 8.4 mm.

Head (Fig. 58 View Figures 58–63 ). Eyes bare; slightly dichoptic, distance between eyes approx. width of ocellus. Face white with dark medial vitta; white pilose; white pollinose. Vertical triangle black; black pilose; lower half weakly white pollinose. Distance between lateral ocellus and eye margin somewhat less than width of ocellus. Frontal triangle black; white pilose; grey pollinose at the sides. Frontal prominence shiny black; black pilose. Occiput black; yellow pilose with a stretch of black pile near the eye margin; grey-white pollinose. Antenna black; antennal arista brown.

Thorax. Scutum black with, dorsally, a pair of faint yellow vittae which fade out posteriorly; lateral yellow vitta very faint; yellow-rufous pilose. Scutellum uniformly yellow-brown; yellow-rufous pilose, with some short black pile interspersed, especially in the posterior half.

Legs. Femora and entire metaleg dark brown to black; pro- and mesofemora and tarsi dark brown; tarsi without a small darkened medial patch. Proleg: Femur without apical pile brush; short black pilose dorsally, long black pilose ventrally, long yellow pilose posteriorly. Tibia long yellow pilose and short black pilose, except for a row of long black pile posterodorsally. Tarsi black pilose dorsally, yellow-orange pilose ventrally. Mesoleg: Femur similar to profemur, but with long, black pile on posterior and posteroventral side and with black pile on anterodorsal side which is markedly longer in the proximal half. Tibia yellow pilose ventrally, except at extreme distal end, where it is also black; short black pilose dorsally; long black pilose anterordorsally, especially in proximal 1/2. Tarsi black pilose dorsally, yellow-orange pilose ventrally, with some thick black pile on ventral side. Metaleg (Fig. 192 View Figures 189–192 ): Femur weakly curved; thickened in distal 1/3; with long yellow pile on anterior and anteroventral side; ventrally with dense, long black pile in proximal 1/3 and less thick and less dense black pile elsewhere; no swelling on the mid-section of the ventral side. Tibia strongly curved, especially from posterior view; flattened; with very long, black pile on dorsal and ventral side. Tarsi black pilose dorsally, yellow-orange pilose ventrally.

Wing (Fig. 139 View Figures 139–142 ). Entire wing uniformly dense microtrichose.

Abdomen (Fig. 95 View Figures 95–100 ). Tergite II with a pair of large, triangular, yellow maculae; anterior and posterior black markings equal in size and with broad medial black marking; black markings with short, stiff black setulae which do not extend to the lateral sides; strongly yellow-orange pilose. Tergite III with a pair of smaller, triangular to rounded yellow maculae in anterior half; strongly yellow-orange pilose. Tergite IV black; long yellow-orange pilose, especially on lateral sides.

Genitalia (Fig. 217 View Figures 217–228 ). Epandrium: Dorsal lobe of surstylus strongly bent, sickle-shaped, short yellow pilose on distal half; with long, thick black setulae at bend ventrally; distal half dorsally broadly convex; densely covered with long yellow pile and with some equally long, but thicker black pile interspersed. Ventral lobe of surstylus bare.

Female.

Unknown.

Distribution.

Democratic Republic of the Congo, Ghana and Togo.

Comments.

The species is very similar in morphology to M. strigilatus and they are sister species in the NJ phylogenetic analysis (but no support for such relationship in the ML analysis). Compared to M. strigilatus , M. nigriceps has a black face, a less curved metatibia, the yellow maculae on tergite II are smaller and more triangular and the yellow abdominal pile on abdominal tergite IV is not so strongly appressed on the sides. The male surstylus is morphologically also similar to that of M. strigilatus , but the thin apex is much longer in M. nigriceps and the dorsal surface of the distal half is more convex in M. nigriceps .