Genus Sphinctomyrmex Mayr, 1866

Key to Asian species of Sphinctomyrmex based on worker caste

1 Antenna 12-segmented; eyes absent; pygidial apex truncate as seen from above; smaller species (WL 0.89-0.92 mm); gastral segments II, III, and IV nearly equal to one another in width and length (Fig. 7) (Thailand) ................................ ................................................................................................ S. siamensis sp. n.

– Antenna 11-segmented; eyes present but small; pygidial apex deeply notched as seen from above; larger species (WL 1.27-1.78 mm); gastral segment II clearly larger than each of segments III and IV in width and length (Fig. 3) ................. 2

2 Larger species (WL 1.68-1.78 mm); body deep reddish brown; petiolar node longer than broad (India, Myanmar, and Thailand) ... S. furcatus (Emery, 1893)

– Smaller species (WL 1.27 mm); body light reddish brown; petiolar node broader than long (India) ................................................................ S. taylori Forel, 1900 Sphinctomyrmex furcatus (Emery, 1893)

Figs 1– 4