New type of spider looking like an ant : Myrmarachne

[Aristide]

The Myrmarachne is a spider which lift its upper legs to look like ants. Doing so, it's extremly hard to tell the difference with a real ant just by sight.
This new mob would look like an ant from a little distance, but when you look closer you'll see that it's a spider that attacks you.

Wikipedia with references images (tw: arachnophobia) : https://en.wikipedia.org/wiki/Myrmarachne