User blog comment:BannedLagiacrus/Monster Appreciation Week: Khezu(4th Gen)/@comment-26150929-20150518020235/@comment-25456685-20150518135341

White Khezu are Genetic Malformations of Red Khezu. Red Khezu actually is the main species, whilst White Khezu is the Subspecies.

But yeah, in short, Mutations. Animals that reproduce quickly and in great quantities have a tendency to develop quite a lot of mutations fairly fast.