I had a look into this melanin-thing again: eumelanin is a special kind of melanin, it's even described in wiki:
http://en.wikipedia.org/wiki/Melanin
So it would be easier to understand if we only use "melanin" as this is some kind of collective noun.
We can leave the phenotypic/genotypic part aside if that is too detailed (in the descriptions so far we only have phenotypic - so to say "visible" definitions); I wanted to explain that color mutants (albinoid, leucistic, melanistic, axanthic) are always (at least in axolotls) recessive and genetically the animal has to be homocygote for this mutant. At least I would like some short definitions for the basic biological words in the glossary: homocygote - heterocygote, recessive - dominant, gene, allel
Every now and then there are questions in the axolotl section of the forum like "I have white and an albino axolotl but some of the offspring seems to be wild type, is this possible?"
But this information is also explained at the color genetics section of axolotl.org
Harlequin and Piebald: I have to admit that I am not so happy with these artificial typing. In my opinion harlequins and piebalds are almost always leucistic axolotls with a higher amount of dark pigments - genetically they obviously are the same as "normal" leucists with a different phenotype.
Golden albino: that's a "normal" albino, too.
"White albinos" lack melanin (the pigment itself) and xanthophores (the pigment cells) or they are combined with leucism (xanthophores are developed, but do not migrate from the neural crest, therefore the animal has only a hint of yellow on head and back).
Whereas golden albinos only lack melanin, xanthophores are expressed so the whole body has a yellow / shiny coloration.
I think we do not need special pictures on that for it's on axolotl.org?
Question on melanoids: In my experience melanoids are not necessarily much darker than normal wildtypes. The only definite characteristic is the missing shiny ring in the eyes.
I added some typos to your text - "chromophore" should be "chromatophore" or are both possible?
Albino (albinism): Color mutant in which the dark pigments ([melanin] and [eumelanin]) are not developed. Animals are usually white or yellow with pink eyes.
Leucistic: A developmental mutation where pigment cells do not migrate from the [neural crest]. The resulting animals are usually white with black eyes.
Melanistic (or melanoid): color mutant where the shiny pigment cells ([iridophores]) are not developed. Melanoid animals are usually much darker in color than normal.
Xanthic: Having more yellow pigment ([xanthophores]) than normal.
Axanthic: Lacking [xanthophores], which produce yellow pigment, usually leading to a dark individual.
Amelanistic: Lacking [melanophores], which produce dark brown/black pigment, often leading to very pale individuals (which may still have other colors present).
Chromatophore: Pigment-containing cell of the skin. There are several different kinds of chromatophores, each containing different types of pigment(s). These include melanophores (containing melanin, a brown-black pigment), iridophores (containing crystals that impart a shiny iridescence), and xanthophores (containing carotenoids and pteridines, yellow and reddish pigments). For more information see [axolotl.org color genetics page].
Iridophore: A pigment-containing cell that contains crystals that impart a shiny iridescence. See [chromatophore].
Xanthophore: A pigment-containing cell that contains carotenoids and pteridines, which impart yellow and red pigments. See [chromatophore].
Melanophore: A pigment-containing cell that contains melanin, a brown-black pigment. See [chromatophore].
Melanin: a group of brown-black pigments that give color to the skin of many amphibians.
Flavistic: a color mutant that has a yellow or golden color.