Thanks to Gerry for ID
Serpiente arborícola, de hábitos nocturnos, delgada
The Mapepire Corde Violon or Blunthead Tree Snake (Imantodes cenchoa) is a slender snake in the colubrid family. It is found from southern Mexico, through Central America and South America. It feeds on geckos, anolis lizards, frogs, reptile eggs, and frog eggs.