Polygyny in Atta texana

[Occultus]

Unlike in most Atta species, it is not uncommon for Atta texana queens to cooperate during colony foundation. It's speculated that this cooperation is due in part to the queens being much smaller than other species of Atta. The smaller queens have fewer energy reserves to raise a colony than the larger queens, joining together would provide an obvious advantage.

Suboptimal field conditions could also play a role in encouraging such cooperation. Multiple queens would stand a better chance of completing their nesting chambers in time.

Even in already established colonies, adding extra queens to a colony cause little to no aggressive resistance. It's not clear if this due to a relatedness amongst wild populations.

Here's an interesting report on the subject based on laboratory raised colonies:
PRIMARY POLYGYNY IN THE ANT ATTA TEXANA :
NUMBER AND WEIGHT OF FEMALES AND COLONY
FOUNDATION SUCCESS IN THE LABORATORY
A. C. MINTZER
https://link.springer.com/article/10.1007%2FBF02223829

Atta texana by Che Hawkins, on Flickr