User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-5361531-20120803131001/@comment-4775842-20120803132015

Piscine wyverns are all wyverns that swim in either water or sand (and occasionally lava). They won't make a new subclass for piscine wyverns, since they all have the same basic shape and same lifestyle (though the diets are likely different).