Pygmaecereus densilanata crest

Another nice crest which is overgrowing its area is Pygmaecereus densilanata crest. My guess is that this is a species which has been clumped with something else, if it was ever commonly accepted, but in this case it doesn't really matter. Once these plants become crested it's almost impossible to discern what the original plant was, accept for the occasional normal offset. But, just out of curiosity, does anyone know anything about this species? Was it legitimately published and if so, by whom? And where would it be included in the currently more accepted taxonomy? It's not even mentioned in Anderson. Feedback?