Synophis insulomontanus, known commonly as the mountain shadow snake, is a species of snake in the family Colubridae.

The species is endemic to northwestern South America.

S. insulomontanus is found in Huánuco Region, Peru.

[1] The preferred habitat of S. insulomontanus is forests on the Amazonian slopes of the Andes in northern and central Peru at elevations of approximately 1,100–1,800 m (3,600–5,900 ft).

[2] A nocturnal, terrestrial, and semiarboreal species, S. insulomontanus has been found foraging on the forest floor in leaf litter, and coiled in bromeliads 1 m (3.3 ft) above the ground.