Hello Gerhard, So did I, I was confused about the great variation of this species too.
But I've realized that they should be identical and would be mentioned as
a 'Form' or a specific cultivar clone.
The variation will be so conspicuous when the plant came from seeds.
Most of
Dyckia marnier-lapostollei in my collection came from a well known
German seed dealer, Kohres Kateen, longtime ago.
I had posted about these in a thread below :
http://www.bromeliads.net/forum/viewtopic.php?t=950
Also, the growth condition could make two plant different.
Some of my friend talked about this topic in another forum, please take a look:
http://forums.gardenweb.com/forums/load ... 23982.html
I would like to meet new friends in other part of the world and would be glad to trade plants or seed from this part of the world.