This species, described some 50-odd years ago, crops up in commercial listings now and again, but almost invariably turns out to be M.sheldonii, with a greater radial spines count then Craig called for it M.alamensis ( 9 ) and usually more than the one central described.
Reppenhagean favours the name, bur without justifying it in any way.
It also surfaced under a Lau collection number (LAU 1401) and it remains to be seen if once again we have a M.sheldonii.
I suspect that even if the required spine-count were found in plants resulting from these collections, we would still have merely an extension to the range of variability of M. sheldonii or even M. mazatlanensis.
Mammillaria - John Pilbeam pag. 318