The Mangrove Pit Viper (Trimeresurus purpureomaculatus) is a highly venomous pit viper species native to Bangladesh, Burma, Thailand, West Malaysia, Singapore and Indonesia.
The colour of the Mangrove Pit Viper is highly variable: it can vary from a uniform dark grey or purplish-brown to a weakly-patterned brown, with a white stripe along each flank, or even greenish-yellow with dark mottling.
Males grow up to a total length of 65 cm, females up to 90 cm.
The Mangrove Pit Viper lives in mangroves and coastal forests and has a reputation for being unpredictable and should be approached with caution. 
Giving no warning signs, this snake will strike readily at any threat, and its powerful haemotoxic venom can cause serious illness or even kill. 
By day it can be found resting on low branches one or two metres from the ground, just like I found it in a mangrove tree.

Pasir Ris Park, Singapore, 24 October 2022