I'm quite sure I've seen this species before in the same area, but was never able to identify it properly. Thanks to finding them in amplexus I was able to understand the characteristics of both male and female. Comparing with descriptions and pictures from the internet I come to the conclusion that this must be D. microcephalus: a species that hasn't been registered in Bolivia yet, but that would be expected considering overall distribution and habitat preferences. I hope someone will be able to confirm this ID. (if interested please write to vincentvosbolivia@gmail.com)