Queen ant ?

I'm not 100% sure, but I think this is a Lasius brevicornis queen. I haven't ever owned a colony of these by the way. Nice spotting!

Nice explanation Atanas Tanev! Thanks for sharing the information!

There was, if you look closely you will see the scars that they left on the thorax. After copulation the queen drops her wings, because she doesn't need them anymore. Also they can became harmful to her, because they are big and stick here and there very easily. So after she drop her wings she becomes very busy to find a good spot for the new anthill and when she is done she will start to dig his first chamber and lay the first eggs She would never see the light from that moment. The higher in evolutionary aspect ants resorbs their wing muscles and reserves as a food till the first workers are born, so they don't need to leave the first royal chamber. Thats why she is so fat and clumsy, but it's better for the both.

It's a queen ant from the genus Lasius I guess.