Probably Brachymyrmex obscurior or B. patagonicus, but the pictures are not great, as you say. Try to use millimeters in your measurements, as that is the scientific convention.
Edited by Batspiderfish, November 27 2016 - 5:27 PM.
If you've enjoyed using my expertise and identifications, please do not create undue ecological risk by releasing your ants. The environment which we keep our pet insects is alien and oftentimes unsanitary, so ensure that wild populations stay safe by giving your ants the best care you can manage for the rest of their lives, as we must do with any other pet.
Exotic ants are for those who think that vibrant diversity is something you need to pay money to see. It is illegal to transport live ants across state lines.
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Black lives still matter.