James K. Langhammer described the Ecuadorian black belly boa as a new subspecies, Boa c. melanogaster in 1983.
These animals featured some differences from other Amazonian populations (Boa c. constrictor). Since there had never existed any scientific name for this form, neither for boas known as Boa c. constrictor in those days, freshly imported snakes were mistakenly labeled as "redtail boa" or, "Peruvian redtail boa", sometimes as "Boa c. rubricauda" (not valid anymore), "Boa c. ortonii" or "Boa c. amarali".
In addition, among "redtail boas" offered by local pet shops there were two different looks. One Amazonian Boa c. constrictor that had light primary color with shining red tail, while the other form had dark overall, mahogany red tail and black ventral surface from unknown origin.
To avoid further confusions, Langhammer decided to describe those dark colored, black bellied specimens as a new subspecies of Boa constrictor, Boa c. melanogaster. Although all 9 specimens used in the description had been collected in surroundings of Rio Yaupi, in Morona Santiago Province, the author also mentioned a specimen from Tena, along Rio Napo that had the same appearance. A photo in Duelllman's book also suggests that distribution of melanogaster may continue to North, towards Santa Cecilia, along Rio Aguarico. Altough Langhammer never knew the exact distribution area, he assumed that Boa c. melanogaster may also occur in Southern Colombia and Northern Peru.
The number of dorsal saddles are 20-21 and usually narrow, almost pitch black colored in the adults. In juvenile specimens ventral surface is highly doted with black flecks and as animals mature they expand and finally fuse into eachother, making a black overall on the ventral surface. Size of adult specimens are similar to Boa c. constrictor; they often reach 8-10 feet in length.
In the past years thanks to some American herpetologists, it has become clear that Boa c. melanogaster is probably only a local color phase of Boa c. constrictor. Animals that are from the neighbouring Peru (Boa c. constrictor) have identical scale numbers (ventral, subcaudal, mid-dorsal scale numbers, dorsal saddles are used as recognition markings) like Ecuadorian black belly boas once described by Langhammer. As it turned out, in distribution of melanogaster the light colored, Amazonian Boa c. constrictor can also be found.
Based on these facts written above, it seems pretty obvious for us that Boa c. melanogaster is probably a natural, wild-existing, distinct color form of Boa c. constrictor, but not a separate subspecies. These boas are very seldom in captivity and almost none has verified origin. I must also notice that some darker Peruvian redtail boas (Boa c. constrictor) that has identical appearance are sometimes mistakenly labaled as " Boa c. melanogaster ". Same happens with dark, black bellied Boa c. constrictor from unknown origin, making lot of confusion among boa enthusiasts.
1.1 CB 2007 Argentine boas
(Boa c. occidentalis)details..