The spider's not really new--in fact, it looks to be one of the oldest extent groups--but it's newly discovered. It's been over a century since such a discovery in spiders.
Velociraptor spider discovered in Oregon cave (pictures):
"Spanning four centimeters with extended limbs, the spider spins sparse webs on cave ceilings. The researchers consider it is most closely related to goblin spiders, but more primitive still. Almost nothing is known about the new species' behavior; even what it eats remains a mystery. In fact, the researchers have tried feeding captured spiders various foods, but to date the arachnids have refused the offerings and perished. Still, its sickle claws suggest that Trogloraptor marchingtoni is a stupendous hunter. "
Thanks to Dee and Croconut for news tips.