The Cryptomaster behemoth may sound like a villain from a superhero film.

But it's actually a newly-discovered species of spider - or more correctly arachnid - living in the forests of Oregon in the US.

Californian scientists found it when they went on an expedition to find out more about its close relative, the Cryptomaster leviathan.

They think the behemoth developed differently when the population was divided by mountain ranges.

Read iWonder's giude to spider super powers.

What are Cryptomasters?

The Cryptomasters are a type of arachnid - which are in the same family as spiders, scorpions, ticks and mites - living in the mountains of southwest Oregon.

Although their 4mm bodies look small, both kinds of Cryptomaster are much larger than many other similar arachnids - and you can find smaller and larger version of each type even though the different sizes have the same genes.

Cryptomasters come from the harvestman family of arachnids, which are said to have got their name because they were seen most often during the harvest season.

They also belong to a wider group of spiders called Laniatores, which are made up of more than 4,100 different kinds of arachnid.

Why is it called a Cryptomaster Behemoth?

Both the leviathan and the behemoth are mentioned in the bible - one is a sea creature and the other is a different kind of large beast.

Scientists chose the name Cryptomaster for the group of arachnids because they are "notoriously difficult to find" and usually hide under logs and leaves on the forest floor.

The species has not been researched very much since its relative the Cryptomaster leviathan was discovered in one place in 1969.

When scientists sat down to examine nearly 80 Cryptomasters they'd collected from 14 different parts of the American state, they realised there was something different about some of them.

They revealed they had discovered the behemoth in their report in the scientific journal ZooKey, calling it "a new monster from southwest Oregon forests".

Unusually, the scientists were mainly able to tell the two species apart because the leviathan has two spikes on its penis, which the behemoth does not have.

Aren't 'daddy longlegs' crane flies?

Harvestmen are also known as daddy longlegs.

But don't confuse it with the crane fly - which is a flying insect that are also called daddy longlegs.

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