There has been considerable confusion surrounding the identity of this species, not least because Reppenhagen when he described it in his first book (1987), pictured what was being grown and has subsequently been named as m.viescensis from a different Series altogether (the Stylothelae).
Both come from the same area of Coahuila, near Viesca.
The plant Reppenhagean illustrates in his major work (1991) shows a hook spined immature seedling to the left of a mature plant with fruit, but with no central spines.
I am of the opinion that this is referable to M.gasseriana, as now defined by Charle Glass and Fitz and Betty Fitz Maurice, and rapresents a variant which has no central spines, except in the seedling stage.
Hunt refers this taxon to synonymy with Mammillaria stella-de-tacubaya.
Mammillaria - John Pilbeam pag.322
Mammillaria chica RS 414
RS 414 - Cerro Bola - Coahuila - Mexico
from "ento" ennio toso collection - savona