With Dirksen's re-work of the genus Eunectes in 2002, they are no longer considered valid subspecies of murinus. Even when they were, there were only extremely slight morphological differences believed to exist between murinus and gigas. According to study data in the literature, the ventral counts, dorsal scale rows, subcaudals, supralabials, and infralabials counts of each never showed enough variation to be significant. It was reported however, that murinus appeared to reach a slightly larger adult size than gigas, and that gigas, or the northern form, did tend to show yellow or orange, in the postocular stripe to a much greater degree than is seen in murinus, the amazon basin form, which tended to have a postocular stripe that closely matches the green ground color of the animal. This I believe was a very generalized statement of an overall trend. This postocular color theory appears to hold true in many cases, but not always. It is currently believed that there is not enough consistent morphological variation, with any measurable characters, that would warrant subspecies classification. The postocular stripe color and adult size differences could easily be, and most likely are, just geographical variations of murinus, due in large part to habitat differences, and do not justify subspecies classification. There are currently four species recognized within the genus Eunectes and there are not any generally accepted subspecies in the genus. There are very few people actively studying the Eunectes group. Interesting stuff,
Kelly
