According to AntWiki, there are only two species of Atta in Ecuador. Based on the head shape, this appears to be A. cephalotes. They range in size from only a few mm in the workers to 2 cm in the case of the potential queens as they leave the nest. There are varying shades of reddish brown, the flying females being the darkest. In the 3rd photo you can see the worker ants (smallest) and the large-jawed Guard ants. The first photos is of the potential queens when they venture forth on their own.
These ants are plenteous in the Amazon rainforest of SE Ecuador and result in huge ant mounds/colonies, some as large as 30-50 yards across with over a dozen entrances. Their trails will stretch for 100 meters to a tree they have selected which a large colony can quickly defoliate. They carry small bits of leaves to the nest which then are used to produce a fungus, which the ants eat.
Outside of being a delicious treat during the months of September and October, when the thousands of potential queens and kings leave the nests, they are very destructive to fruit trees.