Key to the Subgenera of the Crematogaster of the Malagasy region: Workers

1. Antennae 10-segmented................................................................................................................................ Decacrema

- Antennae 11-segmented................................................................................................................................................ 2

2(1) Petiole in dorsal view rectangular, with four angular or acute corners (Fig. 12); very small species (HW <0.75, WL <0.75) ............................................................................................................................................................ Mesocrema

- Petiole in dorsal view variable, but never rectangular; size variable............................................................................ 3

3(2) Petiole in dorsal view ovo-rectangular (Fig. 13), with anterior corners rounded and posterior corners angular or acute, and dorsal face flat; dorso-lateral margins of metanotum carinate (Fig. 14) or angular (Fig. 15), with at least 1 long, flexible seta on either side; very small to small species (HW <0.90, WL <0.90) ............................ Orthocrema

- Petiole shape variable, if ovo-rectangular, then dorsal face concave; dorso-lateral margins of metanotum never carinate; size variable..........................................................................................................................................................4

4(3) Anterior margin of clypeus medially protruding as thin flange over mandibles (Fig. 18), anterior part of clypeus transversely concave; subpetiolar tooth or protrusion absent, petiolar stalk narrow (Fig. 16 b); petiole shape usually more or less slender and suboval (Fig. 16 a), rarely flared or oval ................................................................... Oxygyne

- Anterior margin of clypeus never medially protruding over mandibles (Fig. 19), anterior part of clypeus transversely convex; subpetiolar tooth or protrusion mostly present, variable in size and form, if close to absent (Fig. 17 b), then petiole broadly flared anteriorly (Fig. 17 a) and distinctly wider than long, never slender and suboval; otherwise petiole shape variable. ................................................................................................................................... Crematogaster