We encountered this small bright green tree frog during our hike in a green canyon close to the town of Alto de Tio Diego, Veracruz. Already before we reached the river proper we could hear plenty of frog calls so it was not unexpected when Esme spotted the first frog of that day. See A green tree frog resting on a dead leaf for another large photo of this specimen.
This photo is part of the blog entry Down the grassy slope to the river which has more photos of tree frogs and describes the habitat.