Iridomyrmex anceps is a dull, light to dark brown polymorphic species with large inset eyes high on the head, dense pubescence, relatively long limbs, and distinctive anterior clypeal margin with three convexities. While most Iridomyrmex species are restricted to Australia and New Guinea, I. anceps occurs more broadly. The species is found in the Old World from India, China and Malaysia through the Philippines and Indonesia, across northern Australia and throughout Melanesia, Micronesia and into Polynesia. It is not known whether I. anceps has increased its range with the assistance of human-mediated dispersal, or if its current range was already established prior to contact with humans. The species is present on Tokelau, which is the easternmost Pacific Island with a native ant fauna, but has not been reported from Hawaii. The species is not considered a significant pest across any of its range.