Mammillaria sp. Matahuala MA234.2

I'm a little puzzled about the identity of this plant:



The older areoles have 5 or so spines, with the upper one when present slightly curved. From the newer areoles now, presumably as the plant matures, a very much longer downwars curving spine is being produced. The spines are creamy in colour and tipped darker. It is in a 6cm pot, so I think still quite young, and it hasn't flowered yet.

Matahuala is in the state of San Luiz Potosi, and from researches the cacti that grow around that area (from field lists etc.) are M. heyderi v. meiacantha, M. sempervivi, M. formosa, and M. centralifera / compressa.

It seems to me that the most likely, especially with that long spine is M. centralifera. Does that seem reasonable? and does anyone know who MA is and have access to a field list?

I sowed MA234.2 sp. Matehuala in 2001, the seed offered by Mammillaria Society. The seeds with the acronym MA derived from Cactus Heaven. I have not other information. I'm going to see in my photo archive if I have a plant with flowers.

I didn't remember that they came from the Mammillaria Society, but I have just read the Notes of the Seed Distribution, which sadly isn't much help as it says right at the end, "......sp. Matehuala MA 234.2 about which we know nothing".
Checking Cactus Heaven website, I see that MA234.2 is not, as I had assumed, a field collection number, but simply the catalogue reference number for this seed.
Thanks, Ento, for that information. If you have a photo of an older plant it would be interesting to compare.

My guess would be M. magnimamma (vagaspina). They range quite far north in the state of San Luis Potosi. The spine length can be very different, sometimes very long centrals and then on a neighbouring plant much shorter centrals.

Wolter.

Unfortunately I did not find pictures of plants with flowers, but I put two pictures taken today. When the plant will bloom, I photograph it.

Here is a scan of a slide (scan is a bit poor quality) with a plant that I found about 20 km south of Matehuala and that I called M. magnimamma.

Wolter.