Mesembrius rex 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/251C351C-606C-5B46-884D-CE570E23B925
treatment provided by	ZooKeys by Pensoft
scientific name	Mesembrius rex Curran, 1927
status

Treatment

Mesembrius rex Curran, 1927 View in CoL Figs 19 View Figures 19, 20 , 39 View Figures 39, 40 , 62 View Figures 58–63 , 77 View Figures 75–78 , 99 View Figures 95–100 , 120 View Figures 119–123 , 143 View Figures 143–146 , 154 View Figures 151–154 , 170 View Figures 166–171 , 184 View Figures 181–184 , 221 View Figures 217–228

Mesembrius rex Curran, 1927: 61.

Mesembrius rex - Curran (1939): 10 - Smith and Vockeroth (1980): 504.

Differential diagnosis.

Mesembrius rex males have an entirely black apical pile brush on the profemur, a metatibia with a row of> 10 short, widely spaced black spines (without spines or with dense pile in other species). The metatibia has one deep depression on the posterior side (three in M. perforatus ; none in M. tibialis ) which is not markedly bordered with long black pile (bordered with long black pile in M. chapini and M. sulcus sp. nov.). Females have a frons which is black pilose on its entire length, except laterally. The female can be distinguished from the female of M. sulcus sp. nov. and M. tarsatus by the colour of the tibiae (yellow-brown to chocolate-brown in M. rex ; black in M. sulcus sp. nov. and M. tarsatus ), the absence of black pile on the ventral side of the pro- and mesotibia (present in M. regulus and M. chapini ). It also differs from M. regulus by the concolourous protarsus and protibia (protarsus lighter than distal part of protibia in M. regulus ) and wing cell r1 which is distinctly open (nearly closed in M. regulus ).

Examined material.

Mesembrius rex Curran: Holotype, male, " Mesembrius // TYPE // Mesembrius rex Curran // No." " Taken from Bembex " " Stanleyville , Cgo. // 25°10'E, 0°30'N // IV.7.1915" "Lang & Chapin // collectors" " Stanleyville // Congo // From Leg of // Type [♂]" " Mesembrius // Mesembrius rex // det. Curran // Det. C.H. Curran " [AMNH] [type studied from picture on website]. GoogleMaps

Other material

Democratic Republic of the Congo • 1♀; Bolongo ; 23 Jun 1936; J. Ghesquière leg.; KBIN • 1♀; Lulua, Kapanga ; Nov 1928; Walker leg.; KMMA • 1♀; Basoko ; Oct 1948; P.L.G. Benoit leg.; RMNH • 1♂; Eala ; Oct 1935; J. Ghesquière leg.; RMNH • 1♀; locality and date unknown; J. Ghesquière leg.; KBIN. Malawi • 1♀; Mount Mulanje, Likhubula ; 19 Nov 1912; S.A. Neave leg.; NHMUK • 1♂; Mount Mulanje; 25 Nov 1912; S.A. Neave leg.; NHMUK • 1♀; Mount Mulanje; 2 Dec 1912; S.A. Neave leg.; NHMUK • 1♀; Mount Mulanje; 16 Nov 1912; S.A. Neave leg.; NHMUK • 1♀; Mount Mulanje; 25 Nov 1912; S.A. Neave leg.; NHMUK . Togo • 1♀; Kloto Forest ; Feb 2016; G. Goergen leg.; IITA . Uganda • 1♂; W. shores of Vic. Nyanza, Buddu ; 19-25 Sep 1911; S.A. Neave leg.; NHMUK • 1♂; Barada ; 16 Apr 1940; B. Lebied leg.; NHMUK • 1♂; Entebbe ; 11 Nov 1912; C.C. Gowdey leg.; NHMUK • 2♂♂; Entebbe ; 7 Oct 1971; H. Falke leg.; CNC • Country Unknown • 1♀; locality unknown; 1973; F.M. Hull leg.; CNC.

Re-description male

(Fig. 19 View Figures 19, 20 ). Body length: 14.3-17.0 mm. Wing length: 10.0-11.3 mm.

Head (Fig. 62 View Figures 58–63 ). Eyes bare; holoptic, eye contiguity approximately as long as the length of the ocellar triangle. Face yellow with dark medial vitta; white pilose; white pollinose. Frontal triangle short, black, with a few long, black pile; white pollinose on dorsal half; vertical triangle black, black pilose, yellow pollinose on lower half. Distance between lateral ocellus and eye margin less than 1/2 width of ocellus. Frontal prominence shiny black with orange-brown apex. Occiput black; yellow pilose, with black pile interspersed dorsally; yellow and white pollinose. Antenna, scape and pedicel black; postpedicel brown; antennal arista orange-brown.

Thorax. Scutum black with, dorsally, one pair of grey pollinose vittae; lateral vitta faint, not well-demarcated; pile, especially on the anterior half yellow, but with some black pile interspersed; pile on posterior half very short. Scutellum black in anterior 1/3, brown in middle 1/3, white-yellow in posterior 1/3, with long yellow and shorter black pile. Metasternum with very long, strongly curved golden pile.

Legs. Proleg (Fig. 154 View Figures 151–154 ): Femur black; dorsoventrally flattened; with an apical pile brush of long, black pile dorsally and long, yellow pile ventrally. Tibia orange-brown; with very long, yellow pile on anteroventral side. Basitarsus orange; with a tuft of orange pile on posterior side. Other tarsi very broad; orange; becoming shorter distally; most distal tarsal segment white. Mesoleg: Femur dark brown; with long yellow pile dorsally, except for black pile on dorsal 1/5. Tibia orange-brown; proximal half strongly compressed. Basitarsus orange-brown. Other tarsi dark brown. Metaleg (Fig. 184 View Figures 181–184 ): Coxa with long yellow pile on anteroventrally. Femur long and slender; chocolate-brown; ventrally with a row of> 10 short, widely spaced black spines in the proximal 2/3; with denser, black spines on posterior 1/3; pile otherwise yellow and loose. Tibia orange-brown; with a deep invagination in the proximal 1/3 posteriorly which is bordered with long, black pile ventrally; remainder of ventral side with dense, black pile. Tarsi orange-brown.

Wing (Fig. 143 View Figures 143–146 ). Entire wing uniformly dense microtrichose; brown infuscated in dorsal half.

Abdomen (Fig. 99 View Figures 95–100 ). Tergite II with a pair of large, yellow rounded maculae; black markings hourglass-shaped, white pollinose on posterior end; yellow and black pilose, but black pile more conspicuous in posterior part of black marking. Tergite III with broad yellow fascia and a triangular black marking on posterior half which is strongly white pollinose and covered with short, black spines; yellow pilose otherwise. Tergite IV with large triangular posterior black marking; otherwise yellow with strong white pollinosity.

Genitalia (Fig. 221 View Figures 217–228 ). Epandrium: Dorsal lobe of surstylus short, broadly rounded, with short, black spines on almost entire surface; long brown pilose dorsally. Ventral lobe of surstylus straight; bare.

Description female

(Fig. 39 View Figures 39, 40 ). Body length: 16.0-16.2 mm. Wing length: 11.2-12.5 mm. As M. regulus , but with the following differences: Pro- and mesotibia yellow pilose, with only short black pile on posterior side of mesotibia; protarsus chocolate-brown, concolourous with protibia (Fig. 170 View Figures 166–171 ); wing cell r1 distinctly open. Abdomen (Fig. 120 View Figures 119–123 ) with orange pilosity somewhat more prominent. Head as in Fig. 77 View Figures 75–78 .

Distribution.

Democratic Republic of the Congo, Malawi, Togo and Uganda.

Comments.

The male has a set of unambiguous character states mentioned in the original description and cannot be confused with any other species of the genus. The specimens we have studied correspond with the photographs of the type and are, therefore, considered to be conspecific. Until now, the species was only known from the male holotype. We here report on the first females, which we matched with the males through DNA barcoding. The species seems rare throughout a large part of the Afrotropical Region and seems absent from southern Africa.