Ansonia fuliginea is a highland stream toad endemic to Gunung Kinabalu. Compared to most other congeners, it has a relatively stocky body. The snout is round. The coloration of the flanks is darker than on the middle dorsum and head; the belly also is mostly dark. The upper side skin parts bear many rounded warts. The belly skin is granular. No other frog species of Borneo reaches higher altitudes; A. fuliginea has been recorded at 1600–3480 m asl. 

Males: 32–36 mm, females: 39–44 mm.

Ansonia fuliginea tadpoles are unknown.

The photos on this page ©Kristof Zyskowski