Rubra form and red phase are distint things:

Above you see the rubra form of the green plant below.
The only green area is the growing center of the rosette.
This species is a Santa Catarina native.

These are Northeastern Santa Catarina native.
Here you can see the rubra form.

Red phase are quite common among Dyckias. Many Dyckia species show this redness when induced to it. Dryness and fierce sun strike this effect on Dyckias. This is the red phase. Red phase is not an eternal mood, once watered and the sun amened the plant turns again to its green phase. The red phase is a protection. There is another and definitive shade of red in some Dyckias species. This is the Red Form or the rubra ones. This is forever like diamonds and do not fades away or turns into a faint hue of red. The rubra forms holds their redness year around. Not all the species present the rubra form. Dyckia brevifolia has no rubra form. There is an accepted fake Dyckia encholirioides rubra form. Here the rubra refers to a red spot on the petals, the plant is as green as all Dyckia encholirioides. Here you see some rubra form and they are close to the green form. Note if this was a red form only, every plant should be red. As it is a true rubra form only those are red.