The arboreal boa Corallus caninus is widely distributed across northern South America (the Guianas and Amazonia). We examined geographic variation based on examination of 192 specimens from throughout the range, and revised its taxonomy on the basis of quantitative and qualitative analyses of morphological characters (meristics, morphometrics, and color patterns). Based on the high number of lateral blotches on the body and the high number of scales across the snout, populations south of the Rio Amazonas and west of the Rio Negro are identified as a species (or, potentially, a species complex) separate from C. caninus, and the name Corallus batesii is resurrected for those populations. The distribution of Corallus caninus is restricted to the Guiana Shield (north of the Rio Amazonas and east of the Rio Negro).