The male-based monotypic genus Linepithema Mayr 1866 was shown by Shattuck (1992a) to include around 30 valid worker-based Neotropical taxa of the species-group formerly assigned to the widespread genus Iridomyrmex Mayr. In taxonomically splitting Iridomyrmex sens. lat. Shattuck recognized 6 Old-World genera with species variously Palaearctic, Oriental, Indo-Australian or Australian in distribution, including Ochetellus which is represented in Japan. All of the former South American "Iridomyrmex" were assigned to Linepithema, including the widespread "Argentine Ant" L humile, formerly known as Iridomyrmex humilis, which was recently reported for the first time from Japan (Sugiyama , 1999). Linepithema is distinguished from Iridomyrmex sens. str. by the morphology of its clypeus and differences in mesonotal structure. The Argentine ant has been carried to many parts of the world by human commerce. It is a significant horticultural, domestic and store pest.