Possible Gymnocalycium or Thelocactus or ?

[WAM]

I’m a newbie and have spent a considerable amount of time trying to identify this cactus, but don’t feel confident about this one. I don’t have a good sense as to whether this is a pup to some species that becomes much larger, or will it stay small and more globular like some gymnocalycium? It is currently 2 inches in diameter and about 1.5 inches tall. I had it in an east facing window, which resulted in sun burn and loss of spines. Anyhow, I appreciate any assistance in identifying this one and thank you in advance.

[WAM]

My best guess is Gymnocalycium saglionis. Any additional input it appreciated.

[anttisepp]

Absolutely agreed with WAM's ID. I think this poor small plant suffer from lack of watering and mites also. In good conditions it grows fast and may be compared with ferocacti in size. I have this species from the very beginning and it's among my eldest plants.