The species is endemic to northwestern South America.

[2] The holotype of Synophis calamitus, a juvenile female, measures 223 mm (8.8 inches) in total length, which includes a tail of 74 mm (2.9 inches).

The back and sides of this specimen are iridescent black.

The belly is cream, and the undersurface of the tail is dark gray.

[3] The preferred habitat of S. calamitus is cloud forests north of the Río Toachi at altitudes of 1,900–2,200 m (6,200–7,200 ft).