User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-21378804-20131003110715/@comment-4212769-20131003140230

To say it easily...

Taxonomists wouldn't, the Guild and scientists in MH do. But it's not about that they care if they are subs or not, they consider a sub being a different "breed" of a monster that gives other materials. When it gives different materials to a normal form of this monster it is a "subspecies".

Example:

You can't get the same materials of that green yellow Gigginox as of the normal one? It's a sub.

So it's not about biological precision but about "Does the hunter get what we tell him he would?".