Pristimantis acuminatus Green Rain Frog
Some other names for this species:
Canelos Robber Frog
Madre Selva Biological Station, Loreto, PeruJanuary 16, 2013
Green Rain Frog (Pristimantis acuminatus)
This is one of the few easily identifiable Pristimantis species, because it looks very different than any of the others.

Here is a complete list of the herps I saw in the wild on my 2013 MT Amazon Expeditions trip.

Printed references: