I found this ant, already dead, in a waiting room from a hotel in Ubajara, Brazil. It was pretty big (I'd guess 25 mm at a bare minimum), shiny black with a bit of yellow in the front legs, and rather formidable-looking, with big mandibles and an obvious stinging apparatus.
Despite being found in a building this is definitely not a synanthropic species, there were huge, relatively untamed gardens in the hotel, and it was very close to a national park. When I spotted it, I thought it could be one of my dream species, a bullet ant (which is native to my country, but I never saw one and antmaps.org tells me it isn't recorded in my state), but as I got closer to take pictures I could see it definitely wasn't P. clavata.