I sent my photo to the Serpentario. The director replied that the cute little snake was in fact Xenodon dorbignyi, non-venemous and quite common, with a distinctive red curly bit at the end of the tail that presumably develops with maturity. We don’t see snakes very often, but this is the species we’ve seen the most.
Boooring LOL
Delighted to learn it’s the Xenodon dorbignyi, non-venemous and quite common. Sure looks a lethal one with the devil red tail.