Now that you nention it,the Maraciabo did sometimes have a medium tan heartwood (?) in some planks. I didn't see that in the other species,though it could just have been where it was cut from the log. My Turkish small logs from Unicorn didn't have heartwood,nor do my large logs from the wind instrument maker. Didn't see any in the Zapatero,but they were not logs either. I think you may have the Maracaibo. If so,good. Cut a 5/8"X5/32" strip 1' long,see if it warps. That's the size of the rule billets. Mind you,SOME of them did warp,but most stayed straight. If they get a bit hot from a circular saw,they may warp. We bandsawed,and sanded ours. I would not describe the Maracibo as bone white. Is yours as white as white basswood,or white poplar? If so,I don't know what it might be. I never saw white boxwood of any kind.
Let me make it clear that all the boxwood we tried had non-visible pores. It's just that the Turkish must have the smallest,as over time,tools made from it didn't get hand dirt in the grain.