The knowledge about ants of arid zones of Mexico is very poor. For this reason we assessed the biodiversity of this taxon in 2 sites with different vegetation structure. Ten pitfall traps were placed in each site, and 2 surveys were conducted, 1 in August (rainy season, 2004) and another in February (dry season, 2005). The capture was more abundant in the rainy season
however, during the study, a higher ant diversity was observed in the site with low vegetation cover and few plant diversity. Compared with other arid zones of Mexico, the Zapotitlan de las Salinas Valley is the site with the highest ant species richness. The new records have increased richness to 27 ant species, which is very close to the number of species registered in other localities near Zapotitlan. Our data suggest that increasing sampling effort and application of different sampling techniques, the ant richness species could be increased.
