So... tell me about Leucism

Is it possible for a leucistic herp to contain normal or near normal amounts of both xanthophores and iridophores and yet completely lack melanophores in every area but the eyes? Most definitions of leucism say that true leucism effects the melanophores, xanthophores, and the iridophores nearly equally resulting in the absence or near absence of all three. What would you call an animal with normal eyes, normal xanthophores and iridophores but no melanophores on the body? It isn't quite like normal leucism, and it most definitely isn't an albino. It doesn't seem to be a particularly common condition. You folks who know the proper terminology for such a genetic condition help me out here please.

Leucism is loosely defined as "reduced pigmentation of an animal"... thus there are a lot of variations or degrees that could be considered "leucism"

There is a very common misunderstanding of both Albinism and Leucism. Leucism (or Albinism) is not a particular "mutation". There are any number of mutations that can have a result that fits under the heading "leucistic" (or albino).

Albinism is caused by the absence of melanin... Leucism is a reduction in pigmentation, with one of such pigments being melanin... thus in the most technical of terms, an albino is also leucistic. Because an albino does have "reduced pigmentation".

Of course we, in the reptile hobby, do not use these terms in this way and I do not promote that we do, as it will only cause further confusion. On the contrary it is my opinion that we, in the reptile hobby, should avoid scientific terms at this level as they are very commonly misunderstood, then misused resulting in even more misunderstanding.


In direct response to your question... an animal that has typical yellow pigments (xanthophores) and typical blue/green pigments (iridophores) but has greatly reduced black/brown pigments (melanophores)... can accurately be described as having "reduced pigmentation" which fits under the label of leucistic. Although this is not the ‘typical’ form of laicism…

Spell Check got the best of me in that last paragraph above and I didn't have an edit option...

The last word in the above post should be leucism

Originally Posted by Toby_H

In direct response to your question... an animal that has typical yellow pigments (xanthophores) and typical blue/green pigments (iridophores) but has greatly reduced black/brown pigments (melanophores)... can accurately be described as having "reduced pigmentation" which fits under the label of leucistic. Although this is not the ‘typical’ form of leucism…

Of course we, in the reptile hobby, do not use these terms in this way and I do not promote that we do, as it will only cause further confusion. On the contrary it is my opinion that we, in the reptile hobby, should avoid scientific terms at this level as they are very commonly misunderstood, then misused resulting in even more misunderstanding.


In direct response to your question... an animal that has typical yellow pigments (xanthophores) and typical blue/green pigments (iridophores) but has greatly reduced black/brown pigments (melanophores)... can accurately be described as having "reduced pigmentation" which fits under the label of leucistic. Although this is not the ‘typical’ form of leucism…

Thank you for the response. Any suggestions about what such a morph should be called in the hobby to distinguish it from the more typical form of leucism? I was thinking about calling it a xanthic leucistic morph since when most people in the hobby think of a leucistic they think of a pure white animal(or perhaps one with a small degree of dark spotting) with normal, blue, or black eyes. They don't think of an animal with a body about half white and about half a quite bright yellow or orange. It would be a little confusing to call both that and a pure white leucistic mutation by the same name.

It sounds to me like it would be hypomelanistic...

This is lacking but not totally devoid, of melanin (blacks) but no abnormalities in the other colors nor the eyes...


xanthaphores have high yellows (pastel Ball Pythons would be considered xanthanic)... and axanthic means no yellow (in Latin adding an 'a' to a word makes it an antonym)... and it seems your animal has normal yellows...

I personally steer away from the word Leucism in the pet trade. Scientifically it is a very broad description, yet in the hobby it is used to describe a very narrow array of animals. Quite technically, Pied Ball Pythons are leucistic, but if a handful of us starting referring to them as such it would only cause confusion amongst the masses.

Originally Posted by Toby_H

It sounds to me like it would be hypomelanistic...

This is lacking but not totally devoid, of melanin (blacks) but no abnormalities in the other colors nor the eyes...

No, it doesn't look much like what is normally called hypomelanistic, those usually look like they have a normal but very light and faded coloration. The specimen in question appears to be completely lacking melanin on the body. Anything not yellow is a snowy white. It would look exactly like a leucistic with normal eyes were it not for the quite significant amount of bright yellow coloration in evidence. It isn't quite like any morph I have seen before but the best I can tell from checking multiple sources it seems most likely to be some type of leucism albeit perhaps a somewhat unusual type that allows the yellows to be expressed.

Originally Posted by SethD

No, it doesn't look much like what is normally called hypomelanistic, those usually look like they have a normal but very light and faded coloration. The specimen in question appears to be completely lacking melanin on the body. Anything not yellow is a snowy white. It would look exactly like a leucistic with normal eyes were it not for the quite significant amount of bright yellow coloration in evidence. It isn't quite like any morph I have seen before but the best I can tell from checking multiple sources it seems most likely to be some type of leucism albeit perhaps a somewhat unusual type that allows the yellows to be expressed.

Are you referring to the animals like the "Super Fire" morph of royal python, where although you CAN get bright white animals with dark eyes, you can also get animals that are marked with yellow (and sometimes black) patching?

They are "Partial Leucistics".

Originally Posted by Ssthisto

Are you referring to the animals like the "Super Fire" morph of royal python, where although you CAN get bright white animals with dark eyes, you can also get animals that are marked with yellow (and sometimes black) patching?

They are "Partial Leucistics".

The python "Super Fire's" are about as close to it as I have seen with the exception that the yellow on them isn't very extensive(at least in the pics I have seen) and looks sort of pale and washed out instead of being a bright vibrant color. Also those have dark eyes instead of normal eyes. Still though it is likely a very similar type of trait. It will be interesting to see how variable the offspring are.