No, I haven't heard of it before. But the references on the web suggest tat the name is current in Italy and Hungary. I suspect it is a synonym, as a lot of spurious names are being developed in these countries, from what I have seen. In various lists it is stated ot have a red flower, so that's quite limiting when it comes to Coryphanthas.
Coryphantha pseudoechinus comes from Sierra Paila, and the spination doesn't look dissimilar, except that with this margentae all the spines seem to be white, and the central points oiutward rather than upwards as is described with pseudoechinus. However spine colour variation alone isn't really enough to differentiate a whole species, and besides pseudoechinus has a red flower as well.
So my suspicion is that it should be a synonym of pseudoechinus, but its a nice form. Look at the picture #2 on P136 of Dicht and Luthy and though the spination is tighter, as it would be in habitat, I certainly think there are similarities.
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Chris43, moderator