try garapa, i have some if you wish to test it.
some of the finer timbers to take threads could be olivewood, brown ivory, muhuhu, hornbeam, hard maple, pear, holly, apple and field maple but if you can find a source then try pau marfim.
http://www.hobbithouseinc.com/personal/woodpics/pau%20marfim.htmif you can get hold of it then whitebeam is great for fine detail.
goncalo alves is a cracker for threads but quite orange.
what are you using it for? small boxes???