Key to Simopone grandidieri group workers

This key to the workers of the Simopone grandidieri group is based on Chen, Chen and Zhou (2019).

1

 * In full-face view, outer margins of eye just interrupting lateral margin of head (Figs 5–6 . . . . . 2
 * In full-face view, outer margins of eye not interrupting lateral margin of head (at most toughing the lateral margin as seen in Fig. 7) . . . . . 4

2
return to couplet #1
 * Frontal carina relatively short, ending far away from the level of the anterior margins of eyes; leading edge of scape without standing setae . . . . . Simopone grandidieri
 * Frontal carina relatively long, extending beyond the level of the anterior margins of eye; leading edge of scape with standing setae . . . . . 3

3
return to couplet #2
 * Eyes located far back on head (EP 1.90) . . . . . Simopone laevissima
 * Eyes located slightly more anteriorly on head (EP 0.74–0.84) . . . . . Simopone elegans

4
return to couplet #1
 * Anterior margin of clypeus with a prominent tooth at its midpoint . . . . . Simopone bakeri
 * Anterior margin of clypeus broadly rounded, and without a tooth at its midpoint . . . . . 5

5
return to couplet #4
 * AII almost as broad as long (AIIW/AIIL 0.96) . . . . . Simopone gressitti
 * AII distinctly longer than broad (AIIW/AIIL ≤ 0.86) . . . . . 6

6
return to couplet #5
 * Head in full-face view distinctly trapezoidal; lateral tooth of clypeus inconspicuous . . . . . Simopone chapmani
 * Head nearly rectangular in full-face view (Figs 18, 19); lateral tooth of clypeus conspicuous . . . . . 7

7
return to couplet #5
 * Large species (TL ≥ 8.0 mm); maximum diameter of eye smaller than the minimum distance between eyes; posterolateral portion of dorsal face of pronotum striate longitudinally . . . . . Simopone fisheri
 * Medium-sized or small species (TL ≤ 6.5 mm); the maximum diameter of eye equal to the minimum distance between eyes; posterolateral portion of dorsal face of pronotum smooth and shining . . . . . 8

8
return to couplet #7
 * Medium-sized species (TL = 6.5 mm); posterior margin of head distinct concave; lateral side of 1/3 posterior head gradually convergent . . . . . Simopone yunnanensis
 * Small species (TL = 5.5 mm); posterior margin of head almost straight; lateral side of 1/3 posterior head gradually divergent . . . . . Simopone oculata