My first thought was Black Mesquite, but it seems pretty large for most of the mesquite I have seen. Some variety of Walnut perhaps or as Scott suggested, Ziricote. - Dave
PS I have found The Wood Database to be an excellent source for looking up the other characteristics when trying to identify unknown bits of wood.
I'll quote myself here as after checking the wood database ziricote does have ray flecks on quarter sawn pieces.
IME ziricote looses a lot of its charm/uniqueness when turned round. This would be best used for flat work. Judging the apparent size the board has substantial value.
This is definitely Zircote. I did not want to go through my entire wood stash but I know I have boards that look just like that. Here is a small sampling of one I had readily available.