Rounded petals, hooked yellow spines

Hello, could anyone please help me with this Mammillaria? Maybe zielmaniana, but I'm not convinced. Thanks in advance!

The same image with better resolution

I think that's a young M. sheldonii or grahamii.

Thanks, Chris. A friend of mine have a very similar plant, but flowers are pale pink, almost cream. Do this species (grahami or shedonii) displays a variation in flower color?
(and I'm sorry I didn't introduce myself before, I'll do that in the right section soon).

No, I wouldn't expect a cream flower on a grahamii. There are quite a few hooked spined Mamms with cream flowers though, and at the size of your plant might look similar.

ok, thank you very much, Chris

Good day!
Let's turn our attention to the flower.  
The whole group of M. grahamii has a large pestle. This is a good sign. Typical for these plants.

I think the photo still of zeilmanniana. With yellow spines, and the rounded petals of the flower. (But here I'm not sure.)
In the store there.

Hello, PVV, thanks for taking part here. I think I didn't follow your rationale. Sorry , English is not my native language.
So it is not clear to me whether you are or disagree with the proposition that this plant is a M. grahamii. Thanks a lot.

Some photo to explain PVV concept….

Mammillaria grahamii : big flowers, big petals (pestle?) in little number




Mammillaria zeillmanniana: big number of petals, little flowers in big number








A good suggestion for the plant that you show, could be Mammillaria variabilis……

Thanks for replying.

My plant has relatively big flowers => M. grahamii group

M. variabilis => M. crinita group, the same of M. zielmaniana

I see the petals of my plant as rounded , not acuminate. Is that an important trait? All plants shown here has acuminate petals.

thanks

Hello!
Thank you Maurillio for your help and explanation.

To mmcavall.
Want to reveal your previous text.
In determining the type played a crucial role features are characteristic of the generative organs.
Flowers, fruits, seeds.
The size of the flower on Your photo medium size, about 1 cm.
M. grahamii has a flower size in 2 times more.
Pestle in M. grahamii longer, much projecting over the edge of the flower.
These signs are enough to discard this name.
Your plant does not belong to the group of M. grahamii (incl. mazatlanensis, sheldonii, swinglei).

I noticed the rounded edges of the petals.
So far, that no other thoughts.

Thank you PVV, you made it very clear now. Thank you