Kleinmond scorpion tail spider

I was looking for the already quite wonderful net casting spider I've been keeping an eye out for at the back of the garden, when a bit of rubble in some mess under a leaf suddenly moved. It ran about a bit, and shook when disturbed. The scorpiontail-structure can move (!), curling in and out to suit what looked like fairly feeble attempts at camouflage. Smaller than my pinky nail, between 5 and 10mm long.