Ant mimicking sac spider

This unusual small spider can easily be overlooked as just another ant scurrying around on shrubs, leaves and leaf litter, but closer examination reveals the spider’s camouflage technique. On the front two legs, at the end of the femur and the joint with the patella are pompom like cluster of hairs which, when the legs are brought together look like the head of an ant.

The uncanny resemblance is further enhanced when the spider waves the rest of the front legs around in the same way as an ant would wave it’s antennae. Being small, black and fast moving the impersonator is difficult to spot.

Ant mimicking sac spider (Corinnidae) Pranburia mahannopi

It is thought that the reason for mimicking is less to do with stalking it’s prey, though it does help, but it is rather a protective adaption against the ants they share a living space with. Spiders have one less body part than insects, their heads are fused to the thorax, so the morphological subterfuge bridges this initial optical difference and gives the spider a slight advantage when deciding whether to feast or flee. It is known that ants are more aggressive when they encounter potential predators such as jumping spiders.

This is the first time I have ever knowingly seen this species and discovered it on a leaf in open scrub by a stream in the Kaeng Krachan Forest Complex. Other species of spiders within a two meter radius were Tarantula (was kneeling just centimeters from an active burrow when taking the shots), Lynx, Jumping and Sac spiders. The range for Pranburia mahannopi is currently noted to be the forests of the Malay Archipelago from Thailand and Myanmar to Cambodia.

Next time I will look more closely at any Diacamma sp. ants scurrying around on leaves in case it turns out to be Pranburia mahannopi and will also look more closely where I kneel.

A Diacamma sp. ant

The Pranburia mahannopi on a leaf - looks just like a Diacamma sp. ant