Thanks Stefan, I also had thought maybe a Pilea, but couldn't find a match,
I found it with the Boehmeria genus, it is Boehmeria caudata, and I noticed I had already put an entry of the plant from another trip, it was just in a later stage, making seeds and that confused me!
There are 4 species of it in the Flora do Brasil, Boehmeria nivea is not recorded in it..
http://floradobrasil.jbrj.gov....