Tentamort

Tentamorts are ambush predators that recall both darkmantles (with their tentacles and general shape) and ropers (particularly greater tentamorts, who share a similar surprising intellect and a desire to converse with their meals).  Who knows—in your world they might even be an evolutionary link or a regional variation.  (Note for thinking about in the future: We don’t question that different regions have different races and monsters, but we don’t always apply the same logic as clearly below the surface—the same duergar and drow and ropers tend to be everywhere.  Shouldn’t different continents get different—often radically so—subterranean ecologies?)  Certainly, their specialized gripping and stinging tentacles are evidence of Darwinian forces at work. 

If you’re looking for more ways to differentiate tentamorts, their poison is a good way to do so.  The Bestiary 2 has a few sentences just ripe for dropping into a helpful NPC sage or ranger’s mouth: “Tentamort poison is particularly horrific, as it swiftly liquefies the creature's internal organs into a rancid slurry the monster can then drink with the same stinger, siphoning out the fluid with foul sucking sounds.” 

Oh, and don’t forget that as tentamorts age they cannibalize each other, growing into intelligent, telepathic greater tentamorts.  Good times!

A marsh-dwelling tentamort lurks near a patch of quicksand, dangling its sticky tentacle like a vine.  When struggling travelers grab it, it hauls them out of the quicksand to sting and feast upon them.

Having just devoured several of its fellows, a newly metamorphosed greater tentamort has begun developing telepathic power.  But, accustomed as it is to the silence of its cave home, it unable to handle the influx of thoughts from sentient beings.  Even in the unlikely event adventurers make peaceful contact with it, it still is driven to attack, wailing /Too loud!  Too loud!/ in the mind of anyone touching it.

Adventurers help free a star whale from the nets of a witchwyrd trawler.  Unfortunately, the giant space whale has some parasites living on its back.  Hungry for humanoid flesh, the tentamort brood members attempt to grapple any corsairs who come too close.

—Pathfinder Bestiary 2 261