Porthidium porrasi is a species of hognose pit viper endemic to south-west Costa Rica. Like all pit vipers, P. porrasi is venomous.
Distinguished from similar species with its extremely upright nose and various scale morphologies, the white-tailed snub-nose viper is named commonly after another distinguishing characteristic, its white tail tip which is sometimes cream or yellow. It grows to a maximum of 50 cm. Its head is broad and distinct from its neck.
Porthidium porrasi is a nocturnal/crepuscular, terrestrial snake. It prefers to stay camouflaged under leaf litter and its preferred habitat is rainforests, from sea level to 200 m of elevation.
The white-tailed snub-nose viper is considered to be either ovoviviparous or viviparous.