Siler jumping spiders (Genus Siler) are native Asian jumping spiders first described by French naturalist Eugène Louis Simon in 1889. They are expert ant-hunters.
This one was captured in the forest, east of Lhokseumawe, Aceh. It appears to be a species of Siler lewaense (Prószyński & Deeleman-Reinhold, 2010). The Siler jumping spider is black, I assume it is a male.
Both its physical and behavioral characteristics are very similar to a black ant, allowing this Siler jumping spider to camouflage well. It even easily blends in with a group of ants when hunting.
Black ants tend to like giant sensitive plants. They follow horned treehoppers that suck the sap of giant sensitive plants. The black ants get "honeydew," or liquid waste sprayed by the horned treehoppers.
Siler's jumpers take advantage of this opportunity to hunt black ants. I captured a Siler jumper hunting black ants. It snatched one of them, then led its prey away from the ant group and killed it.