The species featured on six postage stamps are the Timor river frog, the Snake-necked turtle, the Island pit-viper, the Timor monitor, the Bronze-back serpent, and the Saltwater crocodile.
The 50c stamp represents a frog species, Timor river frog. The Timor river frog (Limnonectes timorensis) has extremely smooth skin, with the few warts present confined to the flanks of the body beneath a pair of distinctive ridges that separate the dorsum from the flanks.
The Timor river frog is a large, alert, big-eyed frog, member of the genus Limnonectes and has powerful hind-limbs for leap a considerable distance to escape a predator. The long toes of the hind-feet are partially webbed for swimming.