Key to African and Madagascan Metapone species (Workers)

1. Lateral margins of raised median portion of clypeus markedly convergent anteriorly from the level of the antennal insertions (Fig 6). Petiolar dorsum from above approximately twice as wide as long (Fig 6). Postpetiolar sternite in profile view appearing as a long, slender process (Fig 5) (Madagascar)............................................ M. emersoni Gregg

Lateral margins of raised median portion of clypeus essentially parallel, at most only slightly convergent anteriorly (Fig 8). Petiolar dorsum from above quadrate to transverse, maximally only about 1.4x wider than long (Fig 3). Postpetiolar sternite in side view extended as a much shorter process; digitate or acute in lateral view (Fig 9), obtusely triangular in frontal view... 2

2(1) Median clypeal surface transversely flat to slightly convex; lateral borders not raised; anterior border entire, without median denticles, very slightly concave in frontal view, with a small step-like marginal excision on each side (Figs 12, 15). Smaller species, HW> 0.76mm. (Angola)........................................................... M. africana sp.n.

Median clypeal surface transversely concave, the lateral borders slightly raised, subcarinate; anterior border medially bidentate, lacking anterolateral marginal excisions (Fig 1). Larger species, HW <0.90mm. (Madagascar).................... 3

3(2) Petiolar node from above approximately as wide as long; postpetiolar sternum in side view bluntly rounded (Figs 9, 11)........................................................................................... M. vincimus Alpert

Petiole from above approximately 1.4 times as wide as long; postpetiolar sternum in side view forming a low acute point (Figs 2, 3)............................................................................. M. madagascarica Gregg