The label says...mystax Repp 940

I've had this plant since 1991, when I bought it under the label M. mystax Repp 940. Pilbeam's list of Reppenhagen numbers say (mystex?) multiseta.
Now I know that mystax has pink flowers, and multiseta is a somewhat confused name. But neither of these seems possible for this plant.
As the photo shows, it has white/cream flowers, and typically 4 spines only, the upper of these is slightly curved up towards the apex, and has a very dark almost black tip. The body is not the green of mystax, but more a grey-green colour. The axils have both wool and a very few bristles. It is in a 12.5cm (5") pot.
So I offer it up for identification, as it beats me......

Hello Chris,
No mystax or multiseta. I had have a plant like that and I believe Sonja got it too. If I remember it well, it was named: hamiltonhoytea var. fulvaflora. This plant is very rare in collections and something to take care off. But I'm sure you will.

I've never heard of that variety, hamiltonhoytia yes, but reading Hunt 1985 again, he mentions it, in a rather offhand manner.

I've found an old picture of my plant Chris and it was hamiltonhoytiae. It is similar isn't it? A bit different in spination, but I would say that you found a name for yours

Certainly close, Hugo. I guess the R940 was a mistake in labelling.

It is my 9-year old Mammillaria hamiltonhoytiae. It is similar to your one.

Seems that it is more common than I thought.

Hello Chris,
I received this picture from Sonja ( stekeltje) and it was also labeled as hamiltonhoytea:



She has send me also the picture from Reppenhagen's book which is similar with the plants above except the flowers are pale pinkish, only Reppenhagen named this plant hamiltonhoytea var pilensis. However, I did also a bit of research in the looseleaf collection were I found the information we needed. At first a picture of a normal red flowering hamiltonhoytea:



Here's in short what Linzen wrote about va. fulvaflora: Craig described a yellow-brown flowering population as a var. of hamiltonhoytea. These were growing at the same place as the type, around San Moran, Queretaro. It was Lau who rediscovered in 1974 (L1011) the type of hamiltonhoytea. He identified these plants at first as vagaspina and later as a gigantea form. Lau didn't probably see any flowers. In 1975 Reppenhagen was at the same place (Rep 1033) and ID these plants as hamiltonhoytea. In the next years, there were no foundings of yellow-brown flowering species at the type location, like Craig described. So we assume that the yellow-brown flowering hamiltonhoytea is no more than a form of gigantea which grows also in the Sierra Zamorano, but not on the type location of hamiltonhoytea.

That's it Chris. Your plant could be a gigantea form like Linzen says or if there were no yellow-brown flowering found at the type location, this could also mean that they were all plundered, which I believe it was because Craig described them growing at the same place. You know in earlier years you could plunder all species you wanted from a place. It could be that this plant only appears in collections ( and widespread in Europe I should say). This leave us with doubts anyway.

Many thanks for all that research, Hugo, and to all you contributed with photos of their plants. I'll go with a form of gigantea from the sound of it - fascinating histories - you tend to believe labels from reputable nurseries - though I always knew there was something not right about this - well, after I'd been growing Mamms for a while at least!