This is very interesting, Hugo. I have a couple of plants of Lau 1116, and the central spines are a bit shorter than those in your photo. I think the central spination is quite variable, as each of my plants looks a little different although very similar. The description in Pilbeam isn't very clear, as it seems to allow quite a bit of variation, the problem being that no-one really knows, it seems, what M. supertexta actually was, and it has had to be rediscovered (?) by Lau and then Hunt and Reppenhagen. You rplant has longer central spines than the 2mm or up to 5mm which the expanded description details. So I agree the plant doesn't conform to the description, but think there might well be some confusion as to what supertexta is itself, let alone what this plant called lanata actually is! So a real puzzle perhaps. I seem to remember seeing an article somewhere on the status of supertexta, but cant remeber where - I shall have to do some digging in my journals.
If it's fine tomorrow, I'll try to take some photos of my plants of L1116, and also of a couple of plants that I have labelled as supertexta (FO-001 and one just with K5 as the field number). The FO-001 is from Mesa Grden seed 917.76 and I also have another plant from MG seed ref 917.7 which is supposed to come from Rio Salada, Tecomavaca.