The named bugbear you are killing is not the correct NPC. You are looking for a giant Gorilla......and yes, it will look just like a big ol' Gorilla and unliike any other critter in the zone.
His name is Great Grenadier Gonga.
He spawns on a tower to the left of where the named bugbear by the arena is. Clear the bugbear PH's on top of the tower and Gonga will pop.....may take a few rounds of killing the PH's to get him, but it does work. I just did it yesterday.
There is a picture of him here: http://eq2.allakhazam.com/db/mob.html?eq2mob=9071
Hope that helps,
Okirin, 70 Fury, ButcherBlock