Hello:
This lizard is an Iguanid lizard from the genus Tropidurus. I don't have a key to this group but it looks like what you have is Tropidurus hispidus. They are related to the "Lava Lizards" of the Galopagos. They are a fairly widespread group of South Amewrican lizards. The pet trade sometimes calls them S.A. Collared Lizards.
Hope this helps. Have a Great Day!!!