Because two males will readily fight each other, either in a natural setting, or if put together, they are commonly known as "fighting spider" in South-east Asia. These spiders are commonly kept in matchboxes with a piece of green leaf and a spat of saliva for moisture. A spider that wins fight after fight gets the status of "first king". A common belief is that the darkest males are most aggressive.Source: en.wikipedia.org/wiki/Thiania_bhamoensis
This female Fighting spider was on a Turmeric plant. I used to observe her regularly. But whenever I tried to photograph her she would escape into her hide, which was constructed by sticking 2 large leaves together with silk. One day I found her about 2 feet away from her hide and utilized the opportunity to photograph her. :-)She was a real challenge to photograph as I had to hold the leaf she was on in my left hand and shoot with the right. The camera setup was weighing my arm down and I was constantly cursing the muscle fatigue until I managed to get this shot. :-D