"There comes a time in every cactus's life when" ... oh wait, I think I got that a bit wrong :)

Does anybody could tell me If the ID is right? I think in M. backbergiana too.
Alfonso

Good point, Alfonso. Your plant has more the appearance of M. backebergiana but I don't have one to compare. The multiple rings of flowers are common for that species. You can count spines, although M. haageana is very variable if you include all the subspecies, or you can tell by examining the tubercles. M. haageana tubercles would be four-sided at the base with noticeable corners (if you can see between all the spines) and no latex. M. backebergiana tubercles would have no corners but would have latex. There is a M. backebergiana ssp ernestii which is described as offsettting more readily but only has one central spine.

Alfonso, I would also hedge my bets on backebergiana.

CP