Juvenile Osteocephalus are distinguished from other frogs by the combination of red iris, white elbow and distal part of the upper arm, small white knee spot and large white heel spot. So this frog is definitely in that genus, but at this age it's very difficult (impossible?) to distinguish, for example, Osteocephalus planiceps from Osteocephalus deridens, both of which are found in this area.