Could be Pyrrhocactus wagenknechtii (Ritter)
or Neochilenia wagenknechtii (Backeberg)
which is
Eriosyce heinrichiana ssp. intermedia var. intermedia (Kattermann)
Eriosyce heinrichiana (Ferryman)
The flowers with the narrow base would be a match for heinrichiana.
Eriosyce_heinrichiana_FK81
The problem is that you never know what you have when growing a Neochilenia fobeana.
I didn´t find it listed in the NCL.
Kattermann listed it under : Names with doughtful application, posssibly referable to E. talt. ssp. paucicostata.
Ritter was not sure which plant was described under Nc. fobeana by Backeberg.
Backeberg described Nc. fobeana without type locality.
My E. esmeraldana has pretty big flowers. The main head is about 5cm (two inches) across and the flowers are bigger. Here it is last summer with a single flower.
Here are some other Thelocephala type Eriosyce which flowered in the last couple of days.The diameter of the plant bodies are about 3-4 cm.(1-1.5 inch)
Eriosyce_krausii plant A
Eriosyce_krausii_(Th._malleolata)plant B
Eriosyce_aerocarpa_AW105
Eriosyce_aerocarpa_FK63 . The porrect and long bristles indicate E. aerocarpa already.
Eriosyce_napina_v_duripulpa_RMF 277. The bud looks different than aerocarpa.