Phoneutria fera, maybe? I would love if it is one of them, the most venomous in the world, especially this one, according to the Guinness World Records (vide references). As a measure reference, the egg has about 3 cm diameter.
Brazil interior, Minas Gerais State, rural area.
This specimen was found about two weeks ago, between the hulls of a rotted tree trunk, within a web nest. Its abdomen was rather bulky at that day. Yesterday, I found it in the same place, protecting a large egg. She is very aggressive with anything that bother her and attacks voraciously even a small stick of wood. I think it's a Phoneutria, but I still do not have power to say for sure. I have photos of the first time I met her, without an egg and the abdomen swelled. The file is not with me right now so I'll post it later. p.s. I wish I could make a more readable and detailed macro of it, but I was cautious this time because it is really aggressive.
Lat: -20.68, Long: -41.89
Spotted on Mar 2, 2015
Submitted on Mar 2, 2015
and 6 other people favorited this spotting