Quote Originally Posted by Ravij View Post
If that were the case they would have added the new minions to the list that come with the Behemoth mount and they didn't. It's also already stated the mount item for Behemoth is "Behemoth Horn" on the Optional Service page; Not to be confused with the horn(s) you get from defeating him in his FATE.
The items that summon the GC leaders and the heroes of light are just that, single items which can summon 1 of three possible minions. See these:

Minion of Light: http://www.xiv-minions.com/single.ph...=minions&id=59
Wind-up Leader: http://www.xiv-minions.com/single.ph...=minions&id=60

As for the Behemoth Horn and Nightmare Whistle, they are two separate items.