> For example, the california kingsnake occurs in two pattern morphs -- striped and banded.

There are more than 2 morphs found in the wild. There is the black belly morph, the Long Beach morph, the yumensis morph (with narrow light bands), for example. Some poeple still maintain that yumensis is a valid subspecies, and not an intergrade between Lampropeltis getulus californiae and L. g. nigritus.

Reference
Zweifel, R. G. 1981. Color pattern morphs of the kingsnake (Lampropeltis getulus) in southern California: distribution and evolutionary status. Bulletin Southern California Academy Sciences 80(2): 70-81.