Mesembrius simplicipes Curran, 1929

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/2B80D8D0-9198-5DA3-82C8-F97213F40741
treatment provided by	ZooKeys by Pensoft
scientific name	Mesembrius simplicipes Curran, 1929
status

Treatment

Mesembrius simplicipes Curran, 1929 Figs 17 View Figures 17, 18 , 21 View Figures 21, 22 , 37 View Figures 37, 38 , 41 View Figures 41, 42 , 60 View Figures 58–63 , 64 View Figures 64–69 , 75 View Figures 75–78 , 79 View Figures 79–82 , 97 View Figures 95–100 , 101 View Figures 101–106 , 118 View Figures 113–118 , 122 View Figures 119–123 , 141 View Figures 139–142 , 145 View Figures 143–146 , 166-167 View Figures 166–171 , 193 View Figures 193–196 , 194 View Figures 193–196 , 219 View Figures 217–228 , 223 View Figures 217–228

Mesembrius simplicipes Curran, 1929: 500.

Mesembrius simplicipes - Keiser (1971): 266 - Smith and Vockeroth (1980): 504.

Mesembrius platytarsis Curran, 1929: 501. syn. nov.

Mesembrius platytarsis - Hull (1941): 330 - Keiser (1971): 265 - Smith and Vockeroth (1980): 504.

Differential diagnosis.

Mesembrius simplicipes males lack an apical pile brush on the profemur which is dorsoventrally flattened. The pro- and mesolegs are orange and with a darker area on the dorsal side of the femur. The probasitarsus is laterally expanded and has some long orange pile. The large yellow maculae on the abdomen lack short, black spines on the posterior edges. Scutum and scutellum are entirely yellow pilose. The male of this species cannot be confused with any other species by the lateral lobe on the probasitarsus. Females have a nearly black abdomen with a pair of vague lateral maculae on tergites II and III. The female of M. simplicipes can be distinguished from any other species (except from M. madagascariensis ) by the nearly black abdomen (clearly yellow to orange and black in other species). It can be distinguished from M. madagascariensis by the pro- and mesolegs which are reddish-brown (extensively brown and black in M. madagascariensis ).

Examined material.

Mesembrius simplicipes Curran: Holotype, male: " Mesembrius // TYPE // Mesembrius simplicipes // Curran. // No." " Mesembrius // Mesembrius simplicipes // Curran" " Madagascar // Great Oriental // Forest" "California Academy // of Sciences // Type No. 11230" [CAS] [date and collector unknown; type studied from pictures].

Mesembrius platytarsis Curran: Holotype, male: " Mesembrius // TYPE // Mesembrius platytarsis // Curran. // No." " Madagascar // Great Oriental // Forest" "California Academy // of Sciences // Type No. 11229" [CAS] [date and collector unknown; type studied from pictures].

Other material

Madagascar • 2♀♀; Alaotra, Station Agric. ; 24 Dec 1957; B.R. Stuckenberg leg.; NMSA • 1♀; Analvony ; 30 Mar 1958; F. Keiser leg.; NMB • 1♂; Antananarivo; Nov 1952; E.S. Brown leg.; NHMUK • 1♂; Antananarivo; 18 Oct 1957; F. Keiser leg.; NMB • 1♀; Antananarivo; 13 Dec 1957; F. Keiser leg.; NMB • 2♀♀; Antananarivo; 14 Dec 1957; F. Keiser leg.; NMB • 1♂; Antananarivo; 6 Sep 1958; F. Keiser leg.; NMB • 1♀; Antananarivo; 8 Feb 1970; L. and R. Blommers leg.; RMNH • 1♂; Antananarivo, Ampefy, Lake Kavitaha ; 25 Mar 1959; F. Keiser leg.; NMB • 1♂; Antananarivo, Ampefy, Lake Kavitaha ; 29 Mar 1959; F. Keiser leg.; NMB • 1♂; Antananarivo, Parc Tsimbazaza ; 2 Feb 1968; J.W. Boyes leg.; CNC • 1♀; Antananarivo, Park Tsimbazaza ; 14 Dec 1957; F. Keiser; NMB • 1♀; Antananarivo, Park Tsimbazaza ; 15-22 Oct 1993; C. Kassebeer leg.; NHMUK • 1♂ 1♀; Antananarivo, Park Tsimbazaza ; 16-22 Oct 1993; C. Kassebeer leg.; CNC • 2♂♂; Antananarivo, Park Tsimbazaza ; 16-22 Oct 1993; C. Kassebeer leg.; CAS • 1♂ 1♀; Antananarivo, Park Tsimbazaza ; 16-22 Oct 1993; C. Kassebeer leg.; NMK • 1♀; Antananarivo, Park Tsimbazaza ; 26 Oct 1993; C. Kassebeer leg.; CNC • 1♀; Antananarivo, Park Tsimbazaza ; 26 Oct 1993; C. Kassebeer leg.; CAS • 1♂; Antananarivo, Park Tsimbazaza ; 6 Nov 1993; C. Kassebeer leg.; CNC • 1♂; Antananarivo, Park Tsimbazaza ; 6 Nov 1993; C. Kassebeer leg.; NHMUK • 1♂; Antananarivo, Perinet ; 30 Sep 1957; F. Keiser leg.; NMB • 1♀; Nosivola ; date and collector unknown; RMNH .

Re-description male

(Figs 17 View Figures 17, 18 , 21 View Figures 21, 22 ). Body length: 12.7-13.4 mm. Wing length: 8.8-10.4 mm.

Head (Figs 60 View Figures 58–63 , 64 View Figures 64–69 ). 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; strongly yellow pollinose before anterior ocellus. Lateral ocelli nearly touching eye margin. Occiput black, yellow pilose with a few very short, stiff black setulae near dorsal eye margin; strongly white pollinose. Frontal triangle black; black pilose; strongly yellow pollinose. Frontal prominence shiny reddish-black. Antenna, scape and pedicel very dark reddish-black; postpedicel black; antennal arista reddish-brown.

Thorax. Scutum black with dorsally a pair of yellow pollinose vittae which are less well demarcated posteriorly; with a lateral yellow pollinose vitta; yellow pilose. Scutellum uniformly yellow-brown; yellow pilose.

Legs. Proleg (Figs 166 View Figures 166–171 , 167 View Figures 166–171 ): Femur dorsoventrally flattened; dorsally brown, except proximal 1/5 and distal end; otherwise orange; yellow pile on posteroventral side longer than black pile on posterodorsal side; with a patch of very short black stiff spines on proximal ventral 1/5; pile entirely yellow anteriorly. Tibia orange; with long orange pile, but pile black on ventral distal end. Basitarsus whitish; laterally expanded; with a tuft of orange pile on the expansion; ventrally with some thick stiff pile on the expansion. Other tarsi orange; with orange and black short pile. Mesoleg: Femur as proleg, but without the posterodorsal black pile. Tibia orange; yellow pilose, with some short stiff black pile on distal end ventrally. Tarsi orange; with short black pile and some short stiff black pile ventrally. Metaleg (Figs 193 View Figures 193–196 , 194 View Figures 193–196 ): Femur chocolate-brown, distal end orange; with loose yellow pile on proximal 1/2 to 2/3 and mostly black pilose on distal 1/3 to 1/2. Tibia orange; with short black pile. Metabasitarsus either deeply excavated anteriorly at proximal end and with a lobe (Fig. 193 View Figures 193–196 ) or unmodified (Fig. 194 View Figures 193–196 ); orange; black pilose. Other tarsi orange; dorsally black pilose, ventrally orange pilose.

Wing (Figs 141 View Figures 139–142 , 145 View Figures 143–146 ). Entire wing uniformly very dense microtrichose.

Abdomen (Figs 97 View Figures 95–100 , 101 View Figures 101–106 ). Tergite II with a pair of very large, yellow almost square maculae which expand into the anterolateral corners; black markings hourglass-shaped, posterior part reaching the lateral sides of the tergite; posterior part of black marking with some black pile in the centre which do not extend to the lateral tergite sides; otherwise yellow pilose. Tergite III with a yellow fascia which is almost interrupted by the medial broad black marking; the latter strongly white pollinose anteriorly; with a medial area of white pollinosity; posterior part of black marking with sparse black pile in the centre; yellow pilose otherwise. Tergite IV strongly white pollinose, except for a black medial area and a darker posterior border; yellow pilose.

Genitalia (Figs 219 View Figures 217–228 , 223 View Figures 217–228 ). Epandrium: Dorsal lobe of surstylus short, bent (as a boomerang); irregularly covered with short black spines which are denser at distal and proximal end and at dorsal bend. Ventral lobe of surstylus straight; bare.

Re-description female

(Figs 37 View Figures 37, 38 , 41 View Figures 41, 42 ). Body length: 14.2-14.9 mm. Wing length: 10.0-10.6 mm.

Head (Figs 75 View Figures 75–78 , 79 View Figures 79–82 ). Eyes bare; dichoptic. Face yellow-white with dark medial vitta; white pilose, white pollinose. Frons black in dorsal half and medial part of ventral half, yellow-white on lateral parts of ventral half; black pilose on black parts, white pilose on yellow-white parts. Distance between lateral ocellus and eye margin approx. width of ocellus. Occiput yellow-white; yellow-white pilose; yellow-white pollinose. Frontal prominence shiny black, orange-brown at distal end; scape black; pedicel orange-brown; postpedicel black; antennal arista reddish-brown.

Thorax. Scutum dark brown with one pair of dorsolateral yellow-white pollinose vittae which are vaguely connected posteriorly; with lateral, yellow-white pollinose vitta; short yellow pilose on anterior half, short yellow and black pilose on posterior half. Scutellum yellow-orange; yellow pilose with shorter, black pile interspersed in posterior half.

Legs. Proleg: Femur orange brown with darker, central area on dorsal side; yellow-white pilose with black pile on posterodorsal side and posteroventral distal half. Tibia orange, slightly darkened on ventral distal end; yellow-white pilose. Tarsi orange-brown; basitarsus and second tarsomere yellow-white pilose, other tarsi yellow-white and black pilose. Femur orange brown with darker, central area on dorsal side; yellow-white pilose with black pile on ventral distal half. Tibia orange-brown; yellow-white pilose, with some short, thick black pile at ventral distal end. Basitarsus orange; yellow-white pilose, with short, thick black pile on ventral side. Other tarsi orange-brown; yellow-white and black pilose; with short, thick black pile ventrally, except on most distal tarsomere. Metaleg: Femur dark brown to black, reddish-brown at distal end; yellow-white pilose with shorter and thicker black pile on anteroventral and ventral distal 1/2. Tibia orange-brown; yellow-white and black pilose. Tarsi orange-brown; black and yellow-white pilose dorsally, yellow-orange pilose ventrally.

Wing. Entire wing uniformly microtrichose.

Abdomen (Figs 118 View Figures 113–118 , 122 View Figures 119–123 ). Tergite II with a pair of large orange maculae; with an anterior and posterior black marking which are connected with a parallel-sided central black marking which is 1/5 the tergite width; yellow pilose on maculae and on anterior and central black marking, black pilose on posterior black marking; white pollinose on posterior black marking. Tergite III with orange fascia (approx. 1/2 of tergal length laterally; approx. 1/8 in medially); with posterior large black marking; yellow pilose on most of the orange fascia, black pilose on black marking and central area of orange fascia; strongly white pollinose on posterior half and medial anterior part. Tergite IV similar, but without orange fascia. Tergite V orange-brown with darker lateral sides; yellow-white pilose; white pollinose in anterolateral corners.

Distribution.

Madagascar.

Comments.

Morphologically, the species is similar to M. platytarsis syn. nov. Males of both species differ in the presence ( M. platytarsis syn. nov.) or absence ( M. simplicipes ) of a large lobe on the anterior side of the metabasitarsus. Male genitalia are also very similar (compare Fig. 219 View Figures 217–228 with Fig. 223 View Figures 217–228 ). Females are morphologically similar as well and the supposed difference in the extent of black pile amongst the yellow pile on the frons is unreliable. The mean interspecific p -distance between both species is very low (0.02%) and of what is usually as observed within species. Both species have been described from the same locality, i.e. the Eastern Forest of Madagascar. Keiser (1971) also noted that both taxa often co-occur. We, therefore, consider the presence or absence of the lobe on the anterior side of the metabasitarsus in the male as a polymorphism and consider M. platytarsis Curran, 1929 a junior synonym of M. simplicipes Curran, 1929.