Argania spinosa should be named Sideroxylon spinosum, see the ref below:
Stride, G., Nylinder, S., & Swenson, U. (2014). Revisiting the biogeography of Sideroxylon (Sapotaceae) and an evaluation of the taxonomic status of Argania and Spiniluma. Australian Systematic Botany, 27(2), 104-118.
Interestingly the sister species Sideroxylon mascatense is also edible
But I think that the genus Sideroxylon has been more extensive than that of the Argania, and therefore we believe that the common points between the two genera participate in this inelegance of botanical classification.
It is what we are looking for, a genetic justification with a paleobotanical study. Apparently, there is the argan tree in the natural state at the extreme eastern of the Sahara, it needs an analysis.