This one could be Espadarana prosoblepon. since it has back spots.
I backed away from this little frog and took a second shot for scale. I do not know the species but there are a LOT of very small frog species in Costa Rica!
Tropical frogs can be extremely small and it took me a while to adjust my thinking and stop thinking of frogs as being 4"-5" long. Only then did I begin to spot the smaller species.
