Sorry, hadn't checked in here for a while.
It was Anatoly Tokar's revision of colubrinus that officially sunk the subspecies.
Tokar, A.A. 1996. Taxonomic revision of the genus Gongylophis Wagler 1830: G. colubrinus (L. 1758) (Serpentes Boidae). Tropical Zoology 9: 1-17.
-----
Chris Harrison
San Antonio, Texas

