‘Size matching’ of forager size and prey size is an ecological mechanism that should partition diets both within ant colonies and ensembles. We studied the relationship between ant body size and food size in tropical leaf-litter ant ensembles at different levels. In three plots of primary rain forest in Sabah, Malaysia, we observed altogether 50 species of 18 genera of ants (e.g. Pheidole, Recurvidris, Lophomyrmex, Paratrechina, Odontoponera) that harvested seed particles from baits of milled rice of various particle size. At colony level ‘size matching’ of individual foragers with their load was found only in one of 12 tested species, viz. Pheidole lucioccipitalis. However, ant species differed considerably with respect to ‘seed’ size used: on average, foragers of larger species transported significantly larger ‘seed’ fragments. This was highly significant in a subset of ant species with at least 12 records of size choice per species. But when we investigated resource partitioning within each of the three ant ensembles with a null model, analysis proved that there was a significant overlap in seed size selection of species at two of the sites, thus indicating that food size choice of foragers had little influence on niche patterns and community structure of ants. Ant species with workers that were not matched with their seed resources (viz. Oligomyrmex or Pheidologeton) engaged in cooperative ‘seed’ transport, mass recruitment to and in situ mastication of rice fragments. Mean ‘seed’ transport distance was 38.4 cm.