Locations (that I've spotted): Jahai Bluffs just NW of the sanctuary entrance(before Great Zektuka quest begins, labelled Aggressive Lion(ess)); Barbarous Shore, far SE corner (still all aggressive); Yatendi Canyons, various and alone, gender generated randomly. If passive, the pet is level 5. If aggressive, the pet is level 10. (I'm not positive about the aggressive part as I didn't know aggressive pets could even be tamed.)
Found: Northern Sections of the Shattered Plains (Specifically, I found one in Poisonous Outcrops.) Only passive, level 5. I'd post a screenshot, but I don't have an account online to store images yet.