It really doesn't look like a retic to me, it's a pretty dark/bad picture but it appears to me to be just a regular old circle back boa. Also if you notice in the picture that it appears as though the snake is hanging from something outside of the cameras view off of the top of the picture. All you can see is the front end of a snake and then the back end of a snake hanging down. I'm not convinced that both of these ends are even of the same snake.