Corallus caninus Nederland - website dedicated to the Emerald Tree Boa of South America

The above map shows distribution and collection points of distinct variations of Corallus caninus. 1: Colombia (isolated range]; 2: Northern Shield (Guiana and Surinam [Brokopondo]; 3: Basin; 4: Brazil; 5: Bolivia; 6: Peru; 7: Ecuador. Corallus caninus does not occur north of Colombia or Venezuela.

As mentioned previously, distinctions between the variation are not only based on patterns and coloration. Scale-counts and DNA sequencing provide more reliable data on speciation, so any Amazonian speciation model used would be very complex [cf.: Henderson].
These are the facts to date regarding coloration, pattern, distribution and scale-counts:

1: The Colombian variation is isolated from other populations and has been for quite some time. Scale counts in specimens from this region differ from those in Northern Shield variants. Patterning and coloration in the Colombian C. caninus are characterised by a deeper green and less dominant white blotches dorsally, i.e. very thin white dorsal markings or saddles. Many patternless specimens are found in this location, even specimens with white spots instead of saddles. Scale-counts vary between those found in 'Basins' and the 'Northern Shield' specimens.

2: Northern Shield [i.e. the Guiana Shield, which includes Surinam] variants have distinctively large snout scales in comparison to the 'Basins'. Some of these populations are patternless or may have less distinct white blotches dorsally.

Those found in Guiana may have very yellow bellies compared to those in Surinam and also have a lighter shade of green and more distinctive white markings dorsally. The white dorsal blotches in Northern Shield variants are not uninterrupted, as in the 'Basin' variant. Many will claim that specimens collected in Guiana are more vividly colored and patterned than those found in Surinam, which are darker, particularly those found in Brokopondo. Those found in Surinam are often a darker green. There also specimens which have the appearance of the Northern Shield variants, but with smaller snout scales, as in the 'Basin'. This is most probably due to transitional outcrossing.

3. 'Basin' variants: these are typically patterned with an uninterrupted white dorsal line and sharp featured, thin white saddles [see pictures below]. They are quite different to the Amazon C. caninus, but similar to the Ecuador Basin C. caninus. The scale counts are quite different [smaller snout scales]. 'Basin' variants may occur in any region which borders on or is part of the 'Basin' transitional range, including Ecuador, Brazil, Peru. 'Basins' are generally larger than their counterparts.