Mammillaria can be a really difficult genus to identify since there are tons of species, subspecies and forms, as well as the variability they have.

Without certainty, I would say that yours could be:

1. M. backebergiana
2. M. erythra f. ruber
3. M. magnifica

How do you guys distinguish C. cornifera from C. compacta when juvenile?

Hi Jura. I'm no expert but it could be maybe a Matucana intertexta

These other two are also new acquisitions for the collection. Unfortunately when repotting the Astrophytum myriostigma I found that it had a severe infestation of root mealybugs and the roots were already rotted, even starting to go up into the stem so I decided to chop them off then kept cutting th...

Thanks a lot for the explanation and everything Dave, it is all much more clearer to me now. Greatly appreciated

Interesting Dave. When researching species to identify my cacti I always tend to find that all species have an "accepted scientific name" and several synonyms... so I tend to go by that accepted scientific name. Do you know which is the taxonomic authority that defines which name is the &q...

Ferocactus wislizeni ssp. herrerae. 5 years old approx. Body of 14cm in diameter x 11cm in height approx.

I bought this Astrophytum asterias about a month ago. When I was repotting it about 10 days ago I found out that its roots were rotting and it was also severely dehydrated due to that so I decided to chop them off with the hope of re-rooting it inspired by a member of this group that goes by Hanazon...

Hello Mike! Thank you for the comment. It is really a beauty! I repotted it in January of this year from a much smaller pot and it seems to be truly happy. I have not let its spines get wet when watering it to avoid messing up the neatness of them. I love the spiralling pattern that it has, like fol...

Melocactus neryi, 7 and a half years old approx. Started growing its cephalium around 1 and half years ago.

I agree with George and Dave, it is a Parodia sellowii

You're welcome! And yes it is definitely a rare one and very sought-after as you said, beautiful species. Great addition to your collection for sure. I have wanted one for a long time but I can only find it grafted over here and I don't really like grafted cacti. Hopefully I'll find one on its own r...

Looks like a Mammillaria luethyi I would say

This fellow is about 38cm in height. Notice this year's new growth at the top with the lighter coloured spines and the ring of darker than the rest of the spines of the body just below it which were the ones at the apex of it while it was resting the past dry season. Also notice the difference in sp...

Pilosocereus chrysostele. 4 and a half years old approx.