It looks to be an AR15-style 12g. The hand-guard shape suggests it's a pump-action, but the position of the barrel in the hand-guard gives the impression that there is a gas tube above the barrel. The stock is apparently of the folding type. The photo seems to originate from Central or South America (perhaps Brazil).
Despite a bit of Googling, I can't so far identify it.
So, gentlemen of the SD, I call on your aid once again!
P.S. I know I should really be out shooting, but I have been struck down by that most manly of ailments, the common cold, so am bridging the time between visits from the nurse with firearms trivia.