The Makedonian phalanx -- why such depth?

[Paralus]

There is the possibility that the king’s Royal foot Guards - somatophylakes as Ptolemy evidently referred to them as on occasion – may be the aspis-armed troops about the king.

If this is a serious suggestion, then I guess you are grasping at straws!

Not at all my good man, not at all. If I am grasping at anything it would be your suggestion that the original group from whom the hypaspists were "desceded" were aspis-carrying noblity ("townies" if I recall) that attended the king. Just something else to think about.

And it is clear that Ptolemy did refer to the Royal hypaspists as somatophylakes on more than one occasion. This is when Arrian does not refer to them as hetairoi. Diodorus also calls them somatophylakes at Philip's murder (as well as doryphoroi). Just as clearly they are a distinct unit of the hypaspist corps and scions of the nobility.