Key to Simopone grandidieri group workers

This key to the workers of the Simopone grandidieri group is based on Chen, Zhou & Liang (2015).

1

 * Anterior clypeal margin strongly biconcave in full-face view => 2
 * Anterior clypeal margin never biconcave in full-face view => 3

2

 * Anterior clypeal margin with a median prominence, not evenly shallowly convex or flat across its width => Simopone bakeri
 * Anterior clypeal margin evenly shallowly convex to more or less straight across its width, without a median prominence => Simopone elegans

3

 * Promesonotal suture feebly present, may be almost effaced, never with ribbed trace on dorsum => Simopone grandidieri
 * Promesonotal suture represented by transversely ribbed trace or aligned punctures on dorsum => 4

4

 * Anteroventral process of petiole merely a small, insignificant tooth. Tergite of petiole relatively broad with respect to the pronotum, AIIW/PW 1.14 => Simopone laevissima
 * Anteroventral process of petiole a distinctly recurved hook or spur. Tergite of petiole relatively narrow with respect to the pronotum, AIIW/PW ≤ 1.07 => 5

5

 * Dorsal surface of petiole meets lateral surface in a rounded angle, marginate not obvious; side of petiole with a curved longitudinal carina between the dorsolateral margin and the level of spiracle => Simopone gressitti
 * Dorsal surface of petiole meets lateral surface in a sharp corner, marginate obvious; side of petiole without a curved longitudinal carina between the dorsolateral margin and the level of spiracle => 6

6

 * Head distinctly top triangle. Dorsolateral borders of pronotum and mesonotum round-angled, not marginated laterally => Simopone chapmani
 * Head nearly rectangle. Dorsolateral borders of pronotum and mesonotum approximately rightangled, marginated laterally => 7

7

 * Anterior margin of clypeus weakly convex. Metanotal groove weakly impressed and visible. In dorsal view petiole distinctly widening posteriorly, posterior margin obviously concave. In lateral view petiole not marginated laterally. Sides of petiole and postpetiole with rich hairs => Simopone oculata
 * Anterior margin of clypeus bluntly angled. Metanotal groove absent. In dorsal view petiole weakly widening posteriorly, posterior margin almost straight. In lateral view petiole distinctly marginated laterally. Sides of petiole and postpetiole with very sparse hairs => Simopone yunnanensis