User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-28303251-20130803064921/@comment-6050823-20130804211929

That's the thing, they haven't released what makes the three classes those classes. For all we know, they could be renaming monster classes again so, all we can really do so far is guess(Though from Tetsukabura's description, they are suggesting that it is closely related to frogs and other amphibians.