We found the White-lipped Rain Frog as we hiked during the night in search of the Annulated Tree Boa at Yatama Ecolodge, a prime conservation reserve bordering Braulio Carrillo National Park. It has a brownish coloration, which would help it camouflage really well against the ground and the leaf litter which is the usual habitat for Craugastor frogs, however the one we saw was resting on top of a leaf. Both arms and legs are slightly striped, noticeable only when looking from very close. It actually was a pretty common sight in the trails around the reserve, although most frequently heard than seen.
This is a great picture! Thanks for sharing