1	Forewing length < 3 mm, wing venation greatly reduced and retromargin of metatibia without plumose setae; hind wing without closed cells, veins closing radial and cubital cells, if visible at all, clear and unpigmented (spectral: sensu Mason 1986); forewing with 2Rs and 1rs-m almost always completely absent, thus without indication of submarginal cells; at least distal part of second cubital cell of forewing undefined or defined completely by unpigmented spectral vein traces (i.e., at least 2Cu and 3Cu absent or spectral); vein M of forewing terminating without bend (i.e., 3M lacking) at about position of anterior end of where 1m-cu (which is absent) would occur	2
–	Forewing length typically > 4 mm, wing venation typically not greatly reduced for Meliponini, but if minute and with some wing reduction, then retromargin of metatibia with plumose setae intermixed with simple setae; hind wing typically with radial and cubital cells closed by at least faintly brownish nebulous veins; forewing with one or two submarginal cells usually weakly indicated by nebulous traces of 2Rs and 1rs-m, first submarginal cell usually recognizable; second cubital cell of forewing completely indicated by at least faint nebulous veins (i.e., 2Cu present); vein M of forewing usually extending at least slightly beyond position of 1m-cu and angular at apex of tubular portion of vein (i.e., 3M present), the stub of which is usually at least faintly visible	4
2(1)	Malar space shorter than flagellar diameter; inner margins of compound eyes converging below	3
–	Malar space almost 1/5 as long as compound eye, much longer than flagellar diameter; inner margins of compound eyes nearly parallel	Pariotrigona Moure
3(2)	Yellow maculation present in worker on scape, supraclypeal area, clypeus, pronotal lobe and sometimes on lower paraocular area, apically on mesoscutellum, and laterally on mesoscutum; scape without erect setae; minutely plumose facial setae absent on upper frons; gonocoxae unmodified, with gonostyli articulating more distally; gonostyli elongate, bladelike, expanded and lamellate proximally; genital capsule rectigonal; metasomal sternum VI medio-apically chamfered, bilobed	Ebaiotrigona Engel & Nguyen
–	Yellow maculation lacking, at most with pale yellow brown areas; scape with erect setae; minutely plumose facial setae extending across upper frons; gonocoxae with enormous, arched, proximal extensions, with gonostyli articulating near midlength; gonostyli slender elongate; genital capsule schizogonal; metasomal sternum VI with a single medio-apical process	Lisotrigona Moure
4(1)	Mesosoma and usually head without distinct maculation; retrolateral surface of metatibia with strong longitudinal keirotrichiate ridge above which is a broad, depressed, shiny marginal area	5
–	Mesoscutellum and usually face and mesoscutum with well-developed yellow maculation; retrolateral surface of metatibia with keirotrichiate area broad, nearly reaching retrodorsal margin of metatibia	Austroplebeia Moure
5(4)	Retromarginal setae of worker metatibia and males entirely simple, or some plumose setae only on apical 1/5 or 1/6 of margin; keirotrichiate median zone of retrolateral surface of metatibia separated from shiny superior marginal subglabrate zone by gentle slope (gentle clivulus)	6
–	Retromarginal setae of worker metatibia and some males partly plumose; elevated keirotrichiate median zone of retrolateral surface of metatibia separated from shiny superior marginal subglabrate zone by abrupt slope (abrupt clivulus)	7
6(5)	Mesoscutum margined with whitish, densely plumose, scale-like setae; head and mesosoma dull, with minute close punctures; propodeal dorsum finely reticulate; retrodorsal margin of worker metatibia without plumose setae	Lepidotrigona Schwarz
–	Mesoscutum without conspicuous plumose setae; head and mesosoma shiny, although with minute, rather close punctures; propodeal dorsum smooth, shiny; retrodorsal margin of worker metatibia with plumose setae among setae on apical 1/5 or 1/6 of margin	Papuatrigona Michener & Sakagami
7(5)	Mesoscutellum well projected posteriorly, extending over propodeum as far as posterior propodeal angle (change in slope between basal area and posterior surface) (best seen in profile); malar area linear (= exceedingly narrow to virtually lacking with compound eye appearing to abutt mandibular articulations) or at least narrower than 0.5× diameter of flagellomere III; vein M of forewing straight and ending at or shortly after 1m-cu [genus Tetragonula Moure, s.l.]	8
–	Mesoscutellum short, only slightly projecting over metanotum (best seen in profile); malar area variable, typically as long as diameter of flagellomere III or greater but sometimes ~ 0.5–0.75× diameter of flagellomere III; vein M of forewing bent at trace of 1m-cu, sometimes present only as minute stub beyond bend	9
8(7)	Scape shorter than torulocellar distance; ~ 5 distal hamuli; retromarginal contour of metatibia slightly convex, with superior distal angle subangulate; rastellum and penicillum usually composed of soft setae; forewing membrane rather uniformly colored, typically clear to lightly infuscate; pleural setae pale; forewing marginal cell nearly closed, sometimes with apex of Rs bent and nebulous (i.e., appendiculate), with or without 2r-rs stub arising at bend	Tetragonula (Tetragonula) Moure
–	Scape at least as long as torulocellar distance; 6 distal hamuli; retromarginal contour of metatibia distinctly and broadly convex, with superior distal angle rounded, almost without angulation; rastellum and penicillum composed of stiff setae; forewing membrane markedly bicolored, proximally darkly fuscate; pleural setae fuscous to black; forewing marginal cell more broadly opened apically, apex of Rs never bent (i.e., never appendiculate)	Tetragonula (Tetragonilla) Moure
9(7)	Malar space < 2× diameter of flagellomere III	10
–	Malar space ≥ 2× diameter of flagellomere III	18
10(9)	Mandible unidentate or bidentate, teeth small [genus Heterotrigona Schwarz, s.l.]	11
–	Mandible bidentate, teeth large, deeply incised, i.e., interdental spaces deep [genus Homotrigona Moure, s.l.]	15
11(10)	Basal area of propodeum largely or entirely glabrous, at most with apicolateral patches of setae, if patches present, then broad glabrous area much wider than setal patches and occupying majority of propodeal basal surface	12
–	Basal area of propodeum entirely pubescent or with a narrow medial glabrous area, if glabrous area present, then distinctly narrower than lateral setose areas, frequently width approximately equivalent to medial length of metanotum	13
12(11)	Basal vein (1M) basad 1cu-a; wings strongly bicolorous, proximal portion (darkly infumate in costal, radial, and first cubital cells) contrasting with clear apical portion; mesoscutum and mesoscutellum with abundant, erect, thick, stiff, black, bristle-like setae (similar to those of Heterotrigona s.str.); superior marginal subglabrate zone of metatibial retrolateral surface apically broader than keirotrichiate zone	Heterotrigona (Borneotrigona) Engel
–	Basal vein (1M) confluent with or slightly distad 1cu-a; wings not bicolorous, proximal half generally similar in color to apical half; mesoscutum and mesoscutellum without such erect, thick, stiff, black setae (some species may have fuscous setae but never the thickened, stiff, bristle-like setae); superior marginal subglabrate zone of metatibial retrolateral surface apically narrower than keirotrichiate zone	Heterotrigona (Platytrigona) Moure
13(11)	Basal vein (1M) basad 1cu-a; basal area of propodeum glabrous, without small, wispy apicolateral patches of setae	14
–	Basal vein (1M) distad 1cu-a; basal area of propodeum largely glabrous but with small, wispy, apicolateral patches of setae	Heterotrigona (Sahulotrigona) Engel & Rasmussen
14(13)	Superior marginal subglabrate zone of metatibial retrolateral surface apically broader than keirotrichiate zone; larger bees, forewing length greater than 6 mm	Heterotrigona (Heterotrigona) Schwarz
–	Superior marginal subglabrate zone of metatibial retrolateral surface apically narrower than or at most as broad as keirotrichiate zone; smaller bees, forewing length < 6 mm	Heterotrigona (Sundatrigona) Inoue & Sakagami
15(10)	Basal sericeous area of metabasitarsus present; clypeus ~ 2× broader than long	16
–	Basal sericeous area of metabasitarsus absent; clypeus short, ≥ 2.5× broader than long	Homotrigona (Homotrigona) Moure
16(15)	Basal area of propodeum smooth and glabrous; vertex not elevated posterior to ocelli	17
–	Basal area of propodeum pubescent; vertex elevated posterior to ocelli	Homotrigona (Lophotrigona) Moure
17(16)	Malar space as long as flagellar diameter; clypeus with a transverse row of erect setae along apical margin; metabasitarsus 2× as long as wide	Homotrigona (Tetrigona) Moure
–	Malar space about as long as 1.5× flagellar diameter; clypeus with erect black setae scattered over entire surface; metabasitarsus < 1.5× as long as wide	Homotrigona (Odontotrigona) Moure
18(9)	Vertex with deep depression and elevated ridge rising above level of ocelli, posteriorly without deep, concave, medial notch; mesoscutum with dense covering of short, plumose setae amid scattered erect, black setae; apical metasomal terga with dense, long, apically plumose setae amid erect, black setae, with plumose setae at least as long as black setae; keirotrichiate zone of metatibial retrolateral surface narrower than superior subglabrate zone, and greater than length of apical subglabrate zone	Geniotrigona Moure
–	Vertex without strongly elevated ridge, with faint transverse depression and ridge posterior to ocelli, posteriorly with deep, concave medial incision; mesoscutum without dense covering of short, plumose setae amid scattered erect, black setae; apical metasomal terga with short, scattered plumose setae amid longer, erect, black setae; keirotrichiate zone of metatibial retrolateral surface about as broad as or slightly broader than superior subglabrate zone, and subequal to length of apical subglabrate zone	Wallacetrigona Engel & Rasmussen