Definitely NOT Ae. gamosepala, but I'm not sure what it is. The shape and texture of the leaf is like Ae. fendleri, but that purplish coloration is unusual. If you can post a picture when it blooms it will be a lot easier.

Aech Shelldancer might be a closer call I think if you look at the shape of the leaves. Aech fendleri has a little bit less pointy leaves. The purplish colour on the leaves also look a lot like the colour on my Shelldancer. The blush on my fendleri's leaves is a bit more reddish and also tend to be spread lightly over most of the leave surface.

Might also be Andr skinneri - but sure, the flower will tell the truth!