Pseudophilautus viridis
—
Dull-green Shrub Frog

There are a number of green Pseudophilautus in Sri Lanka. I saw P. femoralis in this area, but this one looks significantly different. My best guess is the insultingly named Dull-green Shrub Frog, which seems to be the only other green Pseudophilautus in this area.
Online references:
- Pseudophilautus viridis account on AmphibiaWeb
- Pseudophilautus viridis account on iNaturalist
- Pseudophilautus viridis account on Amphibian Species of the World
- Rhacophoridae overview on Amphibians of Sri Lanka