These ants don't really have a common name beyond thief ant, but there a numerous species in the group (the now synonymized subgenus "Diplorhoptrum"), so I made one up to distinguish this rather common species. These ants are almost the tiniest in the North American fauna (another species in the genus is smaller). Even the relatively large queens are only about 3.5 mm in total length. They are common but mostly unseen, due to small size and mostly subterranean habits. They are reputed to make a living by stealing and eating the brood and food of larger ants, near which they often live, but this is not well-documented. A tantalizing bit of circumstantial evidence is that lead casts of the nests of larger ants (made by Florida State U. entomologist Walter Tschinkel) often have tiny threads of lead extending off that are just right dimensions for the tunnels of these ants.
Colonies have multiple queens; this one had about 12 that I was able to count.