>>1420186i ususally find this guys in the trails i ride. they are called yarará, pretty poisonous. the biggest in the pic is a females, about a soda can wide.
If a yarará bites, you immediately begin to have hemorrhages, edema, bleeding from the two holes of the fangs and may even have basal hemorrhages and bleeding disorders.
luckily they are not too aggressive, they usually try to hide, but if you step on one of them things can turn ugly.