A cave-dwelling creature named Trogloraptor sounds like the villain of a B horror film, but it's actually a newly discovered type of spider.

A team of scientists discovered the spindly armed arachnid in caves and old-growth forests of Oregon and California and reported the find today in the journal ZooKeys. Because of its unique evolutionary features, Trogloraptoridae is not just a new species or genus, but a new family of spiders. The name Trogloraptor, meaning "cave robber," seems a fitting moniker (above).

The spider is about 1.5 inches wide with its legs stretched out, bigger than a half-dollar coin. It was found living in loose strands of web hanging from cave ceilings and under forest debris. It wields a set of lethal-looking claws (right), but its hunting and fighting behaviors remain to be seen.

Scanning electron micrograph of the claw of the Trogloraptor spider. California Academy of Sciences

It's probably a close relative of the goblin spiders, Oonopidae, evidence suggests. But its anatomy is a mix of old and new evolutionary features, giving spider scientists food for thought.

Scientists from the California Academy of Sciences, San Diego State University, and citizen scientists from the Western Cave Conservancy all helped discover the spiders. The California Academy of Sciences team led the study to analyze and describe the new arachnid family.

Lewis and Clark may have charted the wild Northwest, but Trogloraptor speaks of yet-untold mysteries.

*Source: Griswold C, Audisio T, Ledford J. 2012. An extraordinary new family of spiders from caves in the Pacific Northwest (Araneae, Trogloraptoridae, new family).*ZooKeys 215: 77-102. zookeys.215.3547