I like gymnocalyciums. Most are so easy to grow and flower they don't get the appreciation they deserve. I only have six or seven species but they never let me down for flowers. I don't grow quehlianum but I have a monster of a Gymnocalycium saglionis. I'll try to do a short story on it in my blog in a day or two. Tomorrow (actually today since I am writing this after midnight) is picnic day here in the States, the 4th of July, Independence Day. Lots of burgers, hotdogs, fried chicken and corn on the cob and watermelon. Won't be much time for writing about cactus. :) Beautiful flowers on your G. quehlianum. The gymnos always seem to over achieve. Have a great weekend.
I look forward to the saglionis blog. Enjoy your picnic. I always get tempted by Gymnocalycium seedlings [it is the same with Lithops]. Quehlianum was one of the first plants I got [not this one]. A florist was selling it cheap as the flowers were finished.