I've just found "Formiculture" while I was doing my research on ant keeping.
First of all, in order to detail my ID request, I can say I'm from Northeast Brazil, but nowhere near the Amazon rainforest. In fact, I live closer to Caatinga, an endemic biome similar to the african Savannah, with semi-arid climate.
So, last Friday, after a much anticipated rain, I found groups of ants gathering in every corner of our garage. At first I thought they were regular workers, but taking a closer look I considered that maybe they could be queens. Since I was hoping to start a colony for a long time, I collected a few of them in an improvised "tube" with cotton and water - it isn't easy to find the appropriated tube setup here.
I know I probably shouldn't have placed more than one queen there, but because I found them in groups I thought that maybe it could be a multiple-queen species of ant.
Ok, after 3 days of waiting, I took the tube out of the dark to check on my ants, and there I found out that some eggs had been already laid. I was surprised with how fast it was, but then I started worrying about my multiple-queen experiment.
It seems the 3 queens are laying eggs together, and they are taking care of the eggs collectively too, so I don't think I can simply take them out of there.
I have a few pictures of them here and I'd appreciate if you guys could help me identify those ants so I could know what to expect of this colony (I hope the answer isn't a civil war when the workers are born haha). Some friends of mine said it could be Crematogaster, but they aren't sure.
How I found the queens:
Tube with 3 queens and the eggs (I know the photo is terrible, but for some reason my camera wouldn't focus on the ants):
Thank you very much!
