Zasphinctus siamensis

The type series of this species was collected from the surface of the soil in a shifting agricultural area at an elevation of about 800 m above sea level near a hill-evergreen forest during the dry season.

Identification
Sphinctomyrmex siamensis is most similar to Sphinctomyrmex trux (an Australian species) in general appearance as they share the pygidium truncate when seen in dorsal view, 12-segmented antenna, subtriangular subpetiolar process, and somewhat smooth and shiny dorsa of mesosoma and petiolar node. However, S. siamensis is easily separated from S. trux by the following conditions: much smaller body (HW 0.54-0.58 mm, WL 0.89-0.92 mm in S. siamensis while HW 0.74-0.84 mm, WL 1.12-1.26 mm in S. trux); relatively longer head (CI 77-83 vs 87-89); complete lack of eyes (in S. trux the eyes are present as pigmented dots in the middle of the side of the head); possession of a distinct tubercle in median portion of clypeus (tubercle absent in S. trux); and relatively longer petiole.

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Nomenclature

 *  siamensis. Sphinctomyrmex siamensis Jaitrong, 2016: 6, figs. 5-8 (w.) THAILAND.