Mesembrius regulus (Hull, 1937)

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/48C3F554-CBCC-5493-984B-7E0CD53C6BB6
treatment provided by	ZooKeys by Pensoft
scientific name	Mesembrius regulus (Hull, 1937)
status

Treatment

Mesembrius regulus (Hull, 1937) View in CoL Figs 18 View Figures 17, 18 , 38 View Figures 37, 38 , 61 View Figures 58–63 , 76 View Figures 75–78 , 98 View Figures 95–100 , 119 View Figures 119–123 , 142 View Figures 139–142 , 153 View Figures 151–154 , 171 View Figures 166–171 , 183 View Figures 181–184 , 202 View Figures 201–204 , 220 View Figures 217–228

Tityusia regulus Hull, 1937: 119.

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

Differential diagnosis.

Mesembrius regulus males have a dark brown apical pile brush on the profemur, a strongly flattened protibia with long black pile in the proximal half and long yellow-orange pile in the distal half. The species resembles other species with a dark apical pile brush on the profemur, but the probasitarsus lacks a tuft of orange or black pile as in the other species. It is the only species with a strongly flattened protibia and with very long, thick black pile on the metabasitarsus. 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. regulus ; black in M. sulcus sp. nov. and M. tarsatus ). It differs from M. chapini by the black pile on the protibia which is restricted to the distal half (over the entire length in M. chapini ). It differs from the female of M. rex by the presence of black pile on the ventral side of the pro- and mesotibia (absent in M. rex ), the lighter protarsus compared to the distal part of the protibia (concolourous in M. rex ) and wing cell r1 which is nearly closed (distinctly open in M. rex ).

Examined material.

Tityusia regulus Hull: Holotype, male, "Efufup // Kamerun, // W. Africa // VIII.30.1919" "Carn. Mus. //Acc. 6552" “type” " Tityusia // Tityusia regulus // type Hull" "Monstromyia rex // Hull Curr." [MCZ] [type studied from pictures].

Other material

Benin • 2♂♂ 1♀ ; Calavi ; Apr 2014; G. Goergen leg.; IITA • 1♀ ; Calavi ; Oct 2015; G. Goergen leg.; IITA • 1♀ ; Ifangni-range ; 6 May 2016; G. Goergen leg.; KMMA • 1♂ 2♀♀ ; Ifangni-range ; 19 Mar 2017; G. Goergen leg.; KMMA • 1♂ 1♀ ; Pobé; 27 Jan 2016; G. Goergen leg.; IITA • 1♀ ; Porto Novo ; Mar 2003; G. Goergen leg.; IITA • 1♀ ; Porto Novo ; Dec 2005; G. Goergen leg.; IITA • 1♀ ; Porto Novo ; Jul 2005; G. Goergen leg.; IITA • 1♀ ; Porto Novo ; Jan 2008; G. Goergen leg.; IITA • 1♂ 2♀♀ ; Porto Novo ; Mar 2008; G. Goergen leg.; IITA • 2♂♂ ; Porto Novo ; 31 Jan 2014; G. Goergen leg.; KMMA • 2♀♀ ; Porto Novo ; 27 Jan 2016; G. Goergen leg.; KMMA • 3♀♀ ; Porto Novo ; date unknown; K. Jordaens leg.; KMMA . Democratic Republic of the Congo • 1♀ ; Equateur, Eala ; Oct 1935; J. Ghesquière leg.; KMMA • 1♀ ; Equateur, Eala ; Sep 1935; J. Ghesquière leg.; RMNH • 1♂ ; Equateur, Eala ; Aug 1935; J. Ghesquière leg.; KBIN • 1♀ ; Equateur, Eala ; J. Ghesquière leg.; KBIN • Jan 1936; J. Ghesquière leg.; KBIN • 1♀ ; Equateur, Lopri River; May-Jun 1927; J. Ghesquière leg.; KMMA • 1♀ ; Terr. de Banningville, Kwilu, Panga ; Aug 1945; Fain leg.; KMMA • 1♀ ; Tshuapa, Flandria [= Boteka]; 18 Oct 1945; P. Hulstaert leg.; KMMA • 1♀ ; Ubangi, Nzali ; 3-4 Mar 1932; H.J. Brédo leg.; KMMA • 1♂ ; Uelé, Tukpwo ; Jul 1937; J. Vrijdagh leg.; KMMA . Nigeria • 1♀ ; Lagos; 22 Nov 1911; W.A. Lamborn leg.; OXUM • 1♀ ; Lagos; 20 Feb 1912; W.A. Lamborn leg.; OXUM • 2♂♂ ; Lagos; 21 Mar 1912; W.A. Lamborn leg.; OXUM . Togo; 1♂ ; Kloto Forest ; Feb 2008; G. Goergen leg.; IITA .

Re-description male

(Fig. 18 View Figures 17, 18 ). Body length: 21.5-24.2 mm. Wing length: 13.2-15.0 mm.

Head (Fig. 61 View Figures 58–63 ). Eyes bare; holoptic, eye contiguity 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 lower half. Ocellus and eye touching. Occiput black; yellow pilose; black pilose dorsally; yellow and white pollinose. Frontal triangle short; black; with some long black pile; strongly white pollinose. Frontal prominence shiny black with orange apex. Antenna black; postpedicel strongly white pollinose; antennal arista orange-brown.

Thorax. Scutum dark brown to black with, dorsally, a pair of very faint, grey pollinose vittae which fade out posteriorly; pile short, dense, black and yellow-white. Scutellum yellow-brown with darker anterior border; with dense yellow and, on the posterior half and centre, shorter, black pile.

Legs. Proleg (Figs 153 View Figures 151–154 , 171 View Figures 166–171 ): Femur dark brown; dorsoventrally flattened; with a dark brown apical pile brush; remainder of posterior side with less dense, long brown pile. Tibia orange-brown in proximal 1/3, but darker in distal 2/3; very broad; with brown to black pile which is longer posteriorly. Basitarsus orange-brown, longer than wide. Other tarsi orange-brown; progressively becoming shorter, wider and lighter; most distal tarsal segment greyish. Mesoleg: Femur dark brown; with long yellow pile on ventroposterior 4/5, black on distal 1/5; pile otherwise short and black. Tibia orange-brown; with long black pile ventrally and shorter, strongly curved black pile dorsally. Tarsi orange; with short, black pile. Metaleg (Figs 183 View Figures 181–184 , 202 View Figures 201–204 ): Femur long and slender; orange-brown; with long yellow pile on all but ventral sides, except for long black pile at extreme distal end; pile much shorter and black ventrally. Tibia orange-brown; with brown to black long pile; unmodified. Basitarsus orange-brown; with a very conspicuous thick tuft of very long and very dense brown pile on distal dorsal half; with long brown pile at extreme proximal end ventrally. Second tarsomere orange-brown; with long brown pile posteriorly. Other tarsi orange-brown; sparsely black pilose dorsally, short orange-brown pilose ventrally.

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

Abdomen (Fig. 98 View Figures 95–100 ). Tergite II with a pair of large yellow, rounded maculae; black marking hourglass-shaped; yellow pilose in anterior half and along tergite margins, black pilose in posterior half; black marking white pollinose posteriorly. Tergite III with yellow fascia and a triangular black marking on posterior half which is strongly white pollinose; yellow pilose on anterior 1/3 and along tergite margins, black pilose on posterior 2/3. Tergite IV dark brown to black; yellow-white pilose, but with shorter, black pile medially; strongly white pollinose on anterior 1/3 to 1/2.

Genitalia (Fig. 220 View Figures 217–228 ). Epandrium: Dorsal lobe of surstylus short, broadly rounded; with short, black spines on almost entire surface; long yellow pilose dorsally, especially at proximal end. Ventral lobe of surstylus straight; bare.

Description female

(Fig. 38 View Figures 37, 38 ). Body length: 11.8-16.7 mm. Wing length: 11.2-12.5 mm.

Head (Fig. 76 View Figures 75–78 ). Eyes bare; dichoptic. Face white with dark medial vitta; white pilose; white pollinose. Distance between lateral ocellus and eye margin approx. width of ocellus. Occiput black; yellow and black pilose; yellow pollinose. Frons black; black pilose; yellow pollinose on ventral half, sometimes pollinosity almost absent. Frontal prominence shiny black, orange-brown at distal end; scape and pedicel orange-brown to black; postpedicel black; postpedicel white pollinose; antennal arista reddish-brown.

Thorax. Scutum dark brown to black with, dorsally, a pair of very vague yellow pollinose vittae; short yellow and black pilose.

Legs. All legs brown to black, protibia and protarsus lighter, yellow-brown; protarsus lighter than distal part of protibia; profemur predominantly black pilose, the pile is longer on the posterior and posterodorsal side than on the remainder of the profemur; pro- and mesotibia black pilose in distal 1/2-1/4, otherwise yellow and black pilose.

Wing. Entire wing uniformly dense microtrichose. Wing cell r1 nearly closed.

Abdomen (Fig. 119 View Figures 119–123 ). Tergite II with a pair of large, orange maculae; black medial marking narrow, approximately 1/9 of tergal width; orange pilose on anterior half, black pilose on posterior half; posterior black marking strongly white pollinose. Tergite III with orange fascia (approx. half of tergite length on lateral sides; approx. 1/5 of tergite length in medial area); orange pilose on anterior end, otherwise black pilose; posterior half white pollinose, especially in medial area. Tergite IV as tergite III, but yellow pilose throughout with black pile interspersed on black marking. Tergite V black with or without a pair of vague orange maculae in anterolateral corner; yellow pilose; white pollinose on anterior half.

Distribution.

Benin, Cameroon, Democratic Republic of the Congo, Nigeria and Togo.

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 original species description 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 locally common in west and central Africa.