Hier die Antwort von Blake B.
Both the axanthic and xanthic nauta are actually from the same
population. Both the axanthic trait and patternless trait are recessive
mutations that are very common in the population. Most xanthic and
patterned nauta appear to be het for both axanthic and patternless
traits therefore you can have all the different forms in one clutch. For
some unknown reason the axanthic patternless trait seems to be selected
for in the wild making the xanthic patterned the rarest form.
Scheint wohl wirklich "eine Laune der Natür" zu sein, sehr Interessant wie ich finde