Santa Cruz field station, Depto Loreto, Peru. August 13, 2014.
Found under a palm frond, along the bank of the Rio Orosa, right by the Madre Selva field station. I observed several of these aquatic snakes in the same area, and like most semi-aquatic snakes, they bite viciously when captured.
Peru 2014 Flickr album is here.
HerpMapper records for this species are here.