The species is endemic to the island of Sri Lanka.

[4] The specific name, deraniyagalai, is in honor of Sri Lankan zoologist Paulus Edward Pieris Deraniyagala.

[2] N. deraniyagala is known only from dry northeastern Sri Lanka, where a single specimen was collected north of Trincomalee, near the shore, on a small hillock of about 10 m (33 ft) elevation.

The dorsum is brown, each scale with a dark brown spot, giving the appearance of longitudinal stripes.

A blackish brown area above the eye continues to the top of the snout.