On Genesis, the Araneo can be found in the cave that hold Magmasaur eggs.

The mouth isn’t right. It has 4 mandibles with webbing, clearly pointing a reference to the Predators without their thermal mask.

I where the hell is the cave though

Slow. Keep your distance and they are easily managed. If they get within striking distance they will spray a slowin web, then converge on you. Use ranged weapons to dispatch them