User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-21378804-20131003110715/@comment-4212769-20131003132330

It does make sense...

1. Old World Rath = own subspecies

2. Old World Azure/Pink Rath = mutation of 1.

3. Old World Silver/Gold Rath = own subspecies

4. New World Rath = own subspecies (close related to 1.)

5. New World Azure/Pink Rath = mutation of 4.

6. New World Silver/Gold Rath = own subspecies (close related to 3.)

As easy as that.