Jeff,
Trying to identify an unknown wood from a photo is nearly impossible, especially with with woods that are similar in appearance to mahogany. It would be helpful to have more information about where, when, and how you obtained it, some idea of its density, etc. A wood expert can have difficulties identifying some species even if they have the wood in their hand.
Based on these photos alone, this could be sapele, African mahogany, Honduran mahogany, andiroba, or any one of a number of less common species from Africa, Central America, or South America. Part of the problem with any photo is how true the color rendering is. We have no way of knowing that, and so relying on color alone does not have any validity. The ribbon stripe figure in quartersawn lumber occurs in each of the species that I mentioned above, so again that does not narrow it down much. Since those are the only two features that we have to deal with, we're at a dead end.
Sorry I can't be of more help, but perhaps if additional information could be provided, we could narrow it down some.
Matt