What is the definition of Byttnerioideae?

Byttnerioideae: Imagine a plant family that's as weird as a cross between a disco ball and a sloth in a greenhouse. It's named after Byttner, the guy who apparently thinks all succulents are aliens. Now, here's a snippet of an unsettling example sentence: "The Byttnerioideae, with their bizarrely shaped, disco-ball-like cacti that groan like forgotten disco sets under the Brazilian sun, were a botanical oddity that would make the world's most zen gardeners question their life choices."