I have found yet another site that was updated Jun13, there are now 37 species (Crotalus) and 2 (Sistrurus).
This site gives the legacy of names as well. For example:
Caudisona lucifer var. cerberus COUES 1875
Crotalus viridis cerberus — KLAUBER 1949
Crotalus viridis cerberus — JONES et al. 1981
Crotalus viridis cerberus — STEBBINS 1985: 231
Crotalus viridis cerberus — CROTHER 2000: 60
Crotalus oreganus cerberus — ASHTON et al. 2001
Crotalus viridis cerberus — POOK et al. 2002
Crotalus oreganus cerberus — CAMPBELL & LAMAR 2004
Crotalus cerberus — DOUGLAS et a. 2002
Crotalus cerberus — BEAMAN & HAYES 2008
Crotalus cerberus — HOSER 2009
Crotalus cerberus — WALLACH et al. 2014: 189
This is a database for all species
http://www.reptile-database.org/
As a general rule, the more we learn about snakes and their ways, the less fear we have of them. This is usually not so with the Mamba.
The more one learns of his ways, the greater grows the dread of him.
He, without doubt, is the King of Snakes in South Africa.
For quickness, aggressiveness, and the deadly nature of his venom, he has no equal.
F. W. FITZSIMONS, 1912