I come occasionally across this term, when I read literature from Spain and especially with reference to a certain research team  (Rivera, Obon, Arteaga, Egea, Laguna e.a.). Could someone please provide more info on this taxon?

It's the term Cavanilles used to refer to the dactylifera of North and Central Morocco. One of the distinguishing features is the relatively thin stipe that they had. It would also supposedly refer to the hypothetical wild populations of Morocco that Medjool would descend from. It's used here basically as an OTU to distinguish the native material and material introduced from Morocco. Cavanilles also named P. excelsior from palms found in Elche, and Rivera et al typefied it (saying that if the occidental-oriental lineages were ever split into seperate species " P. excelsior" would be the correct name for the Occidental lineage. I currently use it as a OTU in the same sense)