Key to Subgenera of Trigonisca s.l.

(worker caste)

1.Integument of mesoscutum and mesoscutellum smooth and shiny; preoccipital carina absent; transscutal sulcus between axillae shallowly impressed; mesoscutellum comparatively flat and low, acutely rounded apically in profile and slightly raised above level of metanotum.................................................................2

—Integument of mesoscutum and mesoscutellum matt, microalveolate to tessellate; preoccipital carina present at least laterally, sometimes weakly so; transscutal sulcus between axillae deeply and broadly impressed; mesoscutellum gently convex, broadly rounded apically in profile and distinctly raised above level of metanotum.............................. 3

2.Malar space as long as 2× flagellar diameter; posterior margin of metatibia gently arched, without projection at distal angle; parapenicillum curved but not greatly sinuate; head width 1.0 mm or greater........................................ Leurotrigona Moure

—Malar space as long as flagellar diameter; posterior margin of metatibia somewhat sinuous, with distal angle projected; parapenicillum markedly sinuate; head width less than 1.0 mm........................................ Exochotrigona Engel, n. subgen.

3.Labrum simple; bristles along posterior margin of metatibia as long as or shorter than maximum metatibial width....................................... Trigonisca Moure, s.str.

—Labrum bituberculate; bristles along posterior margin of metatibia distinctly longer than maximum metatibial width...................................... Celetrigona Moure