Yellow Cactus Flower
Parodia ottonis, formerly known as Notocactus acutus, more commonly N. ottonis.
The Huntington has this to say about this little gem:
(T)his is one of the most variable in the genus. It has a wide range in southern Brazil, Uruguay and adjacent Argentina. Most forms are globular, eventually branching to form clumps, with relatively sparse spination that does not hide the bright green epidermis.
I love it when they talk like that. And then they question the whole Parodia genus.
The notocacti have recently been combined with Parodia. This is supported by the DNA research of R. Nyffeler that reveals that Notocactus in the strict sense is closer to Parodia than it is to other segregate genera that are widely accepted as notocacti: Brasilicactus, Brasiliparodia, and Eriocactus. One is left with the choice of calling them all parodias or resurrecting the segregate genera; a third choice is simply to ignore the research and call them what you will.
Now that’s what I usually say!