The sole reproductively active worker in a social species.
Only the alpha worker can mate, and she mates only once with a foreign male. When she is still virgin she goes out of the nest at night in order to attract a foreign male and mate. When a foreign male encounters the virgin alpha he immediately tries to mount her, as shown (photo 3).
In some eusocial species (ants, bees etc) the queen is a monstrous, gigantic creature -- what the scientists call morphologically specialised. But in others the queen is just one female among all the workers, who are also all female, but she won the power struggle so she's the only one who gets to mate.
Soon after mating has started the worker starts to cut the abdomen of the male who do not stop the copulation (photo 4). This is because he has no chance to find another nest with a virgin alpha, and therefore gain fitness by insuring that no other male can mate with this worker.
You should be reading these blockquotes in a bad German accent, I think.
She's called the gamergate. This isn't at all what it looks like. (Actually Google shows there is a gamer thing called GamerGate too.) It's gam meaning marriage, as in gamete and hierogamy, plus erg meaning work as in energy and ergative. She's the married worker.
It takes approximately two minutes for the worker to cut the abdomen of the male, and half an hour to remove the terminal part which remained engaged in her genital tract as a mating plug (photo 5).
Ewww, ugh, that's enough. See www.shef.ac.uk/uni/projects/taplab/tmres.html for the rest of it, and pictures of ants with numbers on them like racehorses.
Other workers, being female, also produce eggs, but being unmated they only produce males.
In such a society there is a competitive caste system, and it is possible for high-ranking workers to overthrow the gamergate dictator, and install themselves in power. Conversely, the gamergate can call on hench-ants to beat up pretenders who look like raising a revolt.
Gamergate status appears to be mediated by pheromones. When the gamergate is experimentally removed, a power struggle among the highest-ranking workers results in one of them taking over and becoming reproductive.