Osteocephalus derides was described by Jungfer et al in this paper in 2000. It's very similar to O. planiceps overall. Dick Bartlett told me that O. deridens has a tympanum about half the size of the eye, whereas O. planiceps has a larger tympanum, so I'm guessing that this one is O. deridens.

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

Based on the smallish tympanum, overall small size, and radiating lines in the iris, I've tentatively identified this Osteocephalus as O. deridens.

Here is a complete list of the herps I saw in the wild on my 2014 MT Amazon Expeditions trip.

Based on the radial pattern in the iris, the relatively small size, and the pattern, I believe this frog is a Osteocephalus deridens. The etymology of this name comes from the original species description: "The specific name is the present participle of the Latin deridere (make fun of someone) in allusion to the males' calls from the treetops that sound as if they are laughing at the collectors' vain attempts to reach them."

My Travelogues and Trip Lists page includes a complete list of the herps I saw in the wild on my 2016 MT Amazon Expeditions trip.

When I first saw this, my brain didn't quite register what it was; it looked like some sort of algae or lichens on an otherwise innocent frog. But it's just crazy coloration/patterning.