Mammillaria columbiana "bogotensis"

I take no credit for this plant, which was collected in 1982 from Sogamoso in Columbia. I acquired it at an auction of a collection owned by our Cactus Society branch secretary who sadly died last year.
Until I saw it, I had no real idea that it would form such a nice plant, with many offsets. It has flowered, and so I hope it will for me next year as well.

After some investigation, this plant comes from Sogamoso, but not the Sogamoso that is the most obvious one ( in the mountains in the state of Boyaca), whoich was my initial thought. A friend suggested to me that if it did, then it would be a new location for this species - not impossible though. So I did some further checking, and now have a much better idea of where it was collected.
It comes from the lowlands - 120 metres - in the state of Santander, on Google maps it is just marked as Puente Sogamoso. That is north of of Barrancabermeja and west north west of Bucamaranga.