User blog comment:BannedLagiacrus/Monster Appreciation Week: Azure Rathalos (4th Gen)/@comment-27125903-20160101174644/@comment-27125903-20160105121430

@Rathalosaurus rioreurensis

I'm going to assume it's because Azure Rathalos was the flagship monster of Monster Hunter Freedom so he probably had a different sound set to stand out from the other subspecies... although bannedlagiacrus likely knows the true answer.

Shame they didn't keep it though...