We describe a new species of Sibon from the Reserva Forestal La Fortuna, Chiriquí Province, Panama. The new species is distinguished from all species presently assigned to Sibon by having 17 rows of dorsal scales at midbody and 15 rows one head length anterior to cloaca (vs. 13 or 15 rows of dorsal scales at midbody without reduction on posterior portion of body in all other species of Sibon), and dorsal scale rows that change orientation from the sides of body toward middorsum (vs. maintaining more or less the same orientation). A key to the Lower Central American species of Sibon is provided.