Mesembrius minor (Bezzi, 1915)

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/918A816B-E60C-525D-8099-4D5B7E1A1DDE
treatment provided by	ZooKeys by Pensoft
scientific name	Mesembrius minor (Bezzi, 1915)
status

Treatment

Mesembrius minor (Bezzi, 1915) View in CoL Figs 14 View Figures 13, 14 , 35 View Figures 35, 36 , 57 View Figures 52–57 , 94 View Figures 89–94 , 116 View Figures 113–118 , 137 View Figures 135–138 , 173 View Figures 172–176 , 198 View Figures 197–200 , 204 View Figures 201–204 , 216 View Figures 205–216

Helophilus (Mesembrius) minor Bezzi, 1915: 96.

Mesembrius minor - Bezzi (1921): 7 - Bezzi (1923): 348 - Curran (1927): 64 - Curran (1939): 10 - Smith and Vockeroth (1980): 504.

Differential diagnosis.

Mesembrius minor males lack an apical pile brush on the profemur and have an unmodified metatibia. The metafemur has a large patch of black pile at the proximal end and, distally, a smaller patch of black pile on the posteroventral side with, anterior to this, a small swelling. The metatibia is unmodified. The maculae on tergite II are very large and rounded and with a narrow black medial vitta. Males differ from males of M. strigilatus in the straight metafemur and metatibia (curved in M. strigilatus ) and from males of other species that lack an apical pile brush in the profemur which has very conspicuous and dense black pile on the ventral side of the metafemur (yellow and less dense in the other species). Females have a frons which is pale pilose on ventral half. Tergite II has a pair of yellow maculae (fascia in M. capensis and spined morph of M. caffer ) and the black posterior marking does not extend to the lateral margins (extends to lateral margins in M. strigilatus ). The metafemur has a marked ventral swelling in the middle (absent in other species; present in M. regulus , but in this species, the pile on the frons is black pilose on the ventral half, except laterally). The pro- and mesotarsi are brown with a darkened medial part, except in the basitarsus.

Examined material.

Helophilus minor Bezzi: Lectotype (hereby designated), male, “LECTOTYPUS” "Hel. (Mes.)// ♂, Type// Helophilus minor //Bezzi" “Syn-//type” "Pres. By//Impl. Bureau Ent.//1915-165." "Chintechi// Nyasaland /; Dr.H.S. Stannus " " Mesembrius // Mesembrius minor n.sp.//Type ♂ " " NHMUK 013428949" [NHMUK]. Female , “Syn-//type” "Hel. (Mes.)// ♀, Type// Mesembrius minor //Bezzi"; " Brit. E. Africa //N. of Mt. Kenia,//nr. crater lake,// 5700 ft. // T.J. Anderson. // 15.II.1911 "; "Pres. By//Impl. Bureau Ent.//1915-165."; " Mesembrius // Mesembrius minor n.sp.//Type ♀ "; " NHMUK 013428950" [NHMUK]. Female, “Syn-//type” " Brit. E. Africa //N. of Mt. Kenia,//nr. crater lake,// 5700 ft. // T.J. Anderson. // 15.II.1911 " "H.(M.) Mesembrius minor Bezzi.// Bezzi det.//1915." "Pres. By//Impl. Bureau Ent.//1915-165." " NHMUK 013428951" [NHMUK].

Other material

Benin • 5♀♀; Azaourissé; 7 Mar 2018; K. Jordaens leg.; KMMA • 1♂; Cotonou ; Feb 2003; G. Goergen; IITA • 1♂; Cotonou ; 14 Dec 2013; G. Goergen and K. Jordaens leg.; KMMA • 4♂♂ 5♀♀; Cotonou ; 28 Jan 2016; K. Jordaens and G. Goergen leg.; KMMA • 1♀; Ouidah ; Sep 2004; G. Goergen leg.; IITA • 1♂; Pobé; 16 Mar 2014; G. Goergen leg.; KMMA • 1♂; Sedjé; Sep 2012; G. Goergen leg.; IITA . Cameroon • 1♀; Maroua, Meskina ; 23 May 2018; M. Azo’o Ela leg.; MAPC • 1♂; Douala ; 9 Jul 1974; J.A.W. Lucas leg.; RMNH . Chad • 1♀; Bebedja ; date unknown; F.A. Bink and R.M. Bink-Moenen leg.; RMNH . Democratic Republic of the Congo • 1♂; Kongo-Central, Boma ; 16 Jun 1915; Lang and Chapin leg.; KMMA • 1♂; Haut-Lomami, Kitompo, Fungwi ; 18 Jun 1911; Dr. Bequaert leg.; KMMA . Mozambique • 1♂; Lower Shire R.; 24 Jun 1916; R.C. Wood leg.; NHMUK .

Re-description male

(Fig. 14 View Figures 13, 14 ). Body length: 11.8-13.3 mm. Wing length: 8.0-9.8 mm.

Head (Fig. 57 View Figures 52–57 ). Eyes bare; slightly dichoptic, distance between eyes approx. the width of ocellus. Face white with dark medial vitta; white pilose; white pollinose. Vertical triangle black pilose; white pollinose in area before ocellar triangle. Distance between lateral ocellus and eye margin less than 1/2 width of ocellus. Occiput yellow; yellow pilose; yellow and white pollinose. Frontal triangle dark black pilose; strongly yellow pollinose on ventral half. Frontal prominence shiny black. Antenna black; antennal arista brown.

Thorax. Scutum black with, dorsally, a pair of well-demarcated yellow vittae and a faint yellow medial line; vittae and line are connected anteriorly and posteriorly; with lateral, yellow vitta; yellow-white pilose. Scutellum uniformly yellow-brown; yellow pilose.

Legs. Femora and entire metaleg brown; pro- and mesofemora and tarsi yellow-brown; small darkened medial patch in all tarsi, except for the basitarsus. Proleg: Femur without apical pile brush; yellow pilose on anterior and ventral side; with shorter, black pile on dorsal and posterior side. Mesoleg: Femur similar to profemur, but also with a row on longer black pile ventrally. Metaleg (Fig. 198 View Figures 197–200 ): Femur with long, yellow pile on anterior side; with a basoventral patch of long, black pile and, somewhat more distally, a smaller patch of long, black pile on the posteroventral side; anterior to this black pile, a small swelling. Tibia unmodified; almost straight.

Wing (Fig. 137 View Figures 135–138 ). Entire wing uniformly dense microtrichose.

Abdomen (Fig. 94 View Figures 89–94 ). Tergite II with pair of very large yellow rounded maculae; black marking hourglass-shaped, with anterior black marking larger than posterior black marking, the latter not reaching the lateral sides of the tergite. Medial black vitta more or less parallel-sided. Black tergal marking with short stiff black pile which does not extend to the lateral sides. Tergite III with small triangular to rounded black marking. Tergite IV with very large rounded black marking occupying most of the tergite; narrowly white pollinose anteriorly. The yellow pile of the abdomen is very short, except on tergite V, where it is not appressed to the lateral sides of the tergite. Tergite V black; strongly white pollinose.

Genitalia (Fig. 216 View Figures 205–216 ). Epandrium: Dorsal lobe of surstylus short, nearly circular; with short black spines on almost entire surface; long yellow pilose dorsally. Ventral lobe of surstylus straight; bare. Hypandrium markedly downwardly curved.

Re-description female

(Fig. 35 View Figures 35, 36 ). Body length: 10.6-13.5 mm. Wing length: 7.5-9.4 mm.

Head. Eyes bare; dichoptic. Face white with dark medial vitta; white pilose, white pollinose. Frons black on dorsal 2/5, yellow-white on ventral 3/5; black and white pilose on ocellar triangle and just ventrally of ocellar triangle, otherwise white pilose; strongly white pollinose on ventral 3/5, weak white pollinose on dorsal 2/5. Distance between lateral ocellus and eye margin slightly less than width of ocellus. Occiput yellow-white; yellow-white pilose; yellow-white pollinose. Frontal prominence shiny black. Antenna dark brown to black; antennal arista reddish-brown.

Thorax. Scutum dark brown with a pair of dorsolateral yellow pollinose vittae which are connected posteriorly; with lateral, yellow pollinose vitta; sometimes with a fine medial white to yellow pollinose vita; yellow pilose. Scutellum yellow-orange; yellow pilose.

Legs. Proleg (Fig. 173 View Figures 172–176 ): Femur black, distal end orange-brown; yellow pilose, with short black pile interspersed. Tibia orange, darkened in distal 1/2; yellow pilose on dorsal proximal half, yellow and black pilose otherwise. Tarsi orange-brown with darkened medial area; black pilose dorsally, yellow pilose ventrally; especially the posterior side has very conspicuous thick black pile. Mesoleg: Femur black, distal end orange-brown; black and white pilose. Tibia orange-brown; orange-yellow pilose on dorsal side, black pilose on ventral side. Tarsi orange-brown with darkened dorsal medial area; black pilose. Metaleg: Femur black, distal end orange-brown; orange-yellow pilose, with short, black pile on dorsal distal end, with shorter and thicker black pile on ventral distal half; with marked ventral swelling in middle (Fig. 204 View Figures 201–204 ). Tibia orange-brown; orange-yellow pilose with some black pile interspersed at distal end. Tarsi black dorsally, orange ventrally; black pilose dorsally; densely orange pilose ventrally.

Wing. Entire wing uniformly microtrichose.

Abdomen (Fig. 116 View Figures 113–118 ). Tergite II with a pair of very large, rounded yellow-orange maculae; black pilose on triangular posteromedial section, yellow pilose otherwise; posterior black marking does not reach the lateral tergal sides; medial part of black marking narrow, approx. 1/10 of tergal width; posterior black marking white pollinose. Tergite III with yellow-orange fascia which occupies entire tergal length on lateral sides and approx. 1/3 of tergal length in medial section; with triangular posterior black marking that does not reach the lateral tergal sides; black pilose on triangular posteromedial section, yellow pilose otherwise; posterior black marking white pollinose. Tergite IV as tergite III but with much narrower yellow-orange fascia (approx. 1/10 of tergal length in medial section). Tergite V with narrow anterior black marking; with a pair of yellow-orange maculae in anterolateral corners, otherwise black; yellow pilose; black marking strongly white pollinose, especially in anterior half.

Distribution.

Benin, Cameroon, Chad, Democratic Republic of the Congo, Malawi and Mozambique.

Comments.

Two female syntypes at the NHMUK (NHMUK-0103428950 and NHMUK-0103428951) are not M. minor as both lack the ventral swelling on the metafemur, the black marking on tergite II is not of the typical hourglass shape and the short black spines on the ventral side of the metafemur are restricted to the proximal half. Syntype NHMUK-0103428950 corresponds to the female of M. capensis , while syntype NHMUK-0103428951 corresponds to the female of either M. strigilatus or M. caffer .