"What also comes to mind is how the lack of melanin affects the other pigments as well in amelanistic tricolors.
With amelanistics tricolors, the red is much brighter without melanin present....so is yellow.
So the old topic rears its ugly head again....can a kingsnake that does not normally express red (like a california king) have an anerythristic morph?
Maybe there's red in there that we cannot physically see but with the lack of those red pigmentation cells maybe the white and black/yellow we do see is affected.....
Is a black and white getula an axanthic by definition? or not?"
Yeah, I know what you mean. I don't believe a Cal. king can be anerythristic at all. It would have to normally express shades of red in it's normal phenotype. They can definitely be hyperxanthic and axanthic though since yellow (xanthin) is a huge part of their natural color scheme.
I also don't think a black and white getula would qualify as "axanthic" by definition unless it is pertaining to a mutation preventing the production of yellow pigment (xanthin), not just because it is black and white in itself.
That BRB is very perplexing though, as it is greatly reduced melanin, as well as possibly being EXTREMELY hypoxanthic. That would also include any possible red xanthophores (erythrophores).
•Red xanthophores (erythrophores) - pterinosomes (drosopterinosomes) are rich in drosopterins which range from orange to red and even violet. These cells are more easily seen on histology than their yellow counterparts and can be seen in the pictures at the top of this page.
Here is another major factor involving how our eyes can perceive certain coloration. These cells themselves don't actually contain any pigment cells, but they can have a great affect on the other chromatophores that do when light passes back through them.
Iridophores - while possessing all the organelles of the other chromatophores, the iridophores primarily use refractile platelets formed by crystals of the uric acid based DNA components called purines. Specifically the purines hypoxanthine, guanine and possibly adenine. Basically these platelets act as prisms and refract light to form certain colors and interact with different pigment bearing chromatophores to vary the colors. These are also the cells that make our eyes see greens and blues when light waves are reflected back through the yellow xanthophore layer.
But even with all this stuff, it can often only leave more questions than hard answers..LOL! Hey, did you read or save those awesome links I posted earlier?. That stuff was interesting as all heck to me.
~Doug
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"a snake in the grass is a GOOD thing" 
serpentinespecialties.webs.com
