There are 2 of these guys that look very similar. One is G. horstii, the other is G. buenekeri. Yours is surely one of these 2...

Alessandro

Thanks Alessandro... fast reply. will check out specific pics if i can find some...otherwise shall label them with both names:)
thanks again

Only four "ribs", lots of pups, very unusual one.

yeap...someone mentioned that to me to...why only four ribs and all the pups , and many on top...I suppose I have to take extra care of it:)
thanks again
SZ

I have one of these, I believe, with 5 ribs. This morning I noticed that it is growing a bud. Seems to be confused about the seasons.It was outside all summmer and I took it in about 6 weeks ago, now it thinks it's time to bloom! Mine also has a fair number of pups, though mostly on teh sides.
Glad to have a possible ID for it. Do the 2 suggested species have noticeable flower differences??

G. buenekeri was originally published as a variety of G. horstii, but the description was invalid on a technicality. It was published again as a separate species although I find no useful differences. Both have very similar pink flowers and the same (usually) five ribbed appearance.

triacanthum?

so how does onee tell the two species apart, or do you need a stereomicroscope and a Phd in botany?

shruns_n_bulbs
thanks for all the info...really helpful. glad to have an unusual one with only 4 ribs and plenty pups ( :)) and can't wait until it might flower. will then post some nice pics, as i have not found many nice ones on the net.TY
SZ

Breton, many people are able to quickly identify a species based on decades of experience. For us with less experience, a knowledge of botanical terms and access to the species description is helpful. There are some published keys to species. Species are often defined by fairly small flower or seed features, while the more obvious features such as colour and spines are extremely variable.

I think Mammillaria are a good species to start with. You can look at spine counts, shapes, and colours to narrow it down to a handful of plants. Add in tubercle shape, wool, bristles, and sap colour, and flowers, and you can almost uniquely identify a species based on quite clear characteristics.

Thanks shrubs'n'bulbs. However I was asking specifically about those two species, so I can determine what my specimen is. I do have a good knowledge of botanical terms,
as I do quite a bit of plant identification for my job and have been keeping many houseplants ( particularly succulents) for several years. I was just wondering if anyone can tell me how to distinguish these two gymnos. I don't presently have access to a good key to cacti.

thanks,
Breton