Eryx colubrinus rufescens was originally described as a separate subspecies of Eryx colubrinus (East African Sandboa). But it was quickly realized that it is nothing more than a dark-backed form of the widespread East African Sandboa.

Actually Kenyan Sandboa is really just another old name for a subspecies that was shown to be invalid as well. Although that subspecies (Eryx colubrinus loveridgei) is no longer valid, hobbyists seem to like the name Kenyan over the more descriptive name East African Sandboa.
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Chris Harrison
San Antonio, Texas