1	Female, antenna with 12 segments (female of M. szetschwanensis (Betrem, 1928) unknown)	2
–	Male, antenna with 13 segments (males of M. bella (Bingham, 1897), M. grossa (Fabricius, 1804) and M. stoetzneri (Betrem, 1928) unknown)	14
2	Fringes of T1–T3 white or whitish (a)	3
–	Fringes of T1–T3 yellow, reddish-yellow or black (aa)	8
3	At least T1 more or less yellow or pale yellow posteriorly (a)	4
–	Metasomal tergites completely black (aa)	6
4	Vertex, behind ocelli, largely smooth (a); frons, in front of ocelli, narrowly smooth (b); mesoscutum smooth medially (c)	M. schulthessi (Betrem, 1928)
–	Vertex (aa) and frons (bb) largely, densely and deeply punctate; mesoscutum entirely densely punctate (cc)	5
5	Spiracular corner (a) and vertical portion of upper plate of metapleuron (b) impunctate; upper plate of metapleuron divided by a well-defined ridge into a punctate dorsal portion and an impunctate vertical portion (c)	M. bella (Bingham, 1897)
–	Spiracular corner punctate (aa); vertical portion of upper plate of metapleuron punctate just below transition from dorsal portion and with few punctures along anterior and posterior sutures (bb); transition from dorsal to vertical portion of upper plate of metapleuron gradual, not carina-like (cc)	M. stoetzneri (Betrem, 1928)
6	Vertex entirely smooth behind ocelli (a); setae blackish above antennal insertion and along inner margin of eyes (b)	M. grossiformis Betrem, 1928
–	Vertex densely punctate behind ocelli (aa); head setae yellow or yellowish-brown (bb)	7
7	Mesoscutum and scutellum smooth, except for few punctures laterally (a); metanotum broadly smooth medially (b)	M. farrenwhitei Betrem, 1928
–	Mesoscutum and scutellum nearly entirely densely punctate, except for more or less smooth area posteromedially (aa); metanotum densely punctate (bb)	M. grossa (Fabricius, 1804)
8	Fringes of T1–T4 blackish-brown to black; wings distinctly darkened	M. binghami (Betrem, 1928)
–	Fringes of T1–T4 brown or yellowish-brown (a); wings subhyaline and yellowish (b)	9
9	T1 and T2, sometimes including T3, with a yellow or pale yellow band posteriorly (a)	10
–	Tergites entirely black (aa)	11
10	Bands on tergites distinct, T3 usually with yellow area posteriorly (a); scutellum largely smooth medially (b); basal elevation of T2 (“gradulus”) distinctly developed (c)	M. formosensis Betrem, 1928
–	Bands on tergites indistinct, T3 without yellow area (aa); scutellum evenly and densely punctate (bb); basal elevation of T2 absent (cc)	M. limbata (de Saussure & Sichel, 1864)
11	Vertex smooth latero-posteriorly (a)	M. lindenii (Lepeletier, 1845)
–	Vertex coarsely punctate latero-posteriorly (aa)	12
12	Scutellum largely smooth (a); wings without infuscation subapically (b); median groove of frons distinct (c)	M. farrenwhitei Betrem, 1928
–	Scutellum punctate anteriorly (aa), if largely smooth, then wings with subapical infuscation (bb); median groove of frons partly or almost completely missing (cc)	13
13	Fringes of T1–T4 yellowish-brown and black on other tergites (a); antenna black (b); scutellum entirely or only anteriorly punctate (c)	M. prismatica (Smith, 1855)
–	Tergites setae yellowish-brown; antenna reddish-yellow; scutellum largely smooth	M. ceylonica (Kirby, 1889)
14	Tergites setae red or reddish-brown (a); legs yellowish-brown (b)	M. ceylonica (Kirby, 1889)
–	Setae pale yellowish (aa) or reddish-brown and, on T6–T7, black (aaa); legs mainly black (bb)	15
15	Clypeus mostly black, at most with two small lateral yellowish areas above mandible base	16
–	Clypeus at least broadly yellow laterally (a)	19
16	Wings more or less darkened (a)	M. binghami (Betrem, 1928)
–	Wings subhyaline (aa)	17
17	Posterodorsal margin of pronotum pale yellow; scutellum without medio-longitudinal carina	M. schulthessi (Betrem, 1928)
–	Posterodorsal margin of pronotum only indistinctly narrowly yellow posteriorly (a); scutellum and metanotum with a more or less distinct medio-longitudinal carina (b)	18
18	Setae on mesosoma yellowish and sparse (a); punctures sparse, intervals 1–2× larger than puncture diameter (b)	M. formosensis (Betrem, 1928)
–	Setae on mesosoma reddish and dense (aa); punctures dense, intervals often smaller than puncture diameter (bb)	M. szetschwanensis (Betrem, 1928)
19	Clypeus always black medio-ventrally and remainder more or less yellow (a)	20
–	Clypeus always yellow medially (aa)	22
20	Yellow bands on T1 wide, covering nearly 1/3 of T1; scutellum always with two lateral yellow spots	M. limbata (de Saussure & Sichel, 1864)
–	Yellow bands on T1 narrow, at most covering 1/5 of T1; scutellum often entirely black, rarely with yellow spots	21
21	Hind femur yellow ventrally (a); S2–S4 often with yellow cuneate maculae lateroapically (b)	M. farrenwhitei Betrem, 1928
–	Hind femur black ventrally (aa); S2–S4 rarely with yellow maculae (bb)	M. prismatica (Smith, 1855)
22	T5 usually with yellow band posteriorly; setae of mesosoma dirty white; pronotum black	M. grossiformis Betrem, 1928
–	T5 without a yellow band (a); setae of mesosoma reddish or yellowish-brown (b); pronotum entirely or mostly reddish-yellow (c)	M. lindenii (Lepeletier, 1845)