There appear to be at least two totally unrelated woods that use this common name and I have no idea which applies to the woods pictured on this page that are not specifically designated. The two are:
Clarisia racemosa of the family Moraceae (this is the name most commonly associated with the wood)
Licania spp. of the family Chrysobalanaceae --- this genera has hundreds of species, at least a couple of which appear to use the common name guariuba), including Licania buxifolia and Licania macrophylla, but I do not know if either of these produce lumber.
Given the extreme variations in grain and color, it certainly appears that either some of these were mislabeled or else there are definitely multiple species.
my samples: NOTE: these pics were all taken in very bright incandescent lighting --- colors will vary under other lighting conditions
planks, all from the same vendor
planks, all listed with the species name Clarisia racemosa