Rebutia (Aylostera) aureiflora was discovered by C. Backeberg in Salta, Jujuy, Argentina and first described in Der Kakteenfreund 1, p. 124, by C. Backeberg in 1932. I have been unable to locate a copy. However the description was re-published by Backeberg two years later (as Mediolobivia aureiflora), in Blatter Fur Kakteenforschung (Bulletin of Cactus Research) together with a black-and-white photograph.

Here is the text of the description in the original Latin and German together with Backeberg’s own English translation. You should look up the original for more details.

MEDIOLOBIVIA AUREIFLORA Bckbg. n. sp. (DER KAKTEENFREUND, 1. Jahrgang, Heft 11, 1932, als Reb. aureiflora)

Proliferans, atrovirens saepe rubescence. Costae in tubercula orbicularia, 6 mm lata dissolutae. Areolae exigue brunneo-tomentosae. Aculei 15-20, setosi, albidi, seu brunneo-albi. Ex iis 3-4 centrales, ad 1 cm longi. Flos ca. 4 cm latus, aureus, fauce albo, petalis in 2 series ordinatis.
Tubus squamis viride-rubre mucronatis praeditus. Fructus setosus, exiguus. Semina opaca, brunneo – nigra.
Patria Salta, ad 2800 m.

Gruppenbildend, dunkelgrün, meist rötlich überhaucht, mit schwach braunfilzigen Areolen. Rippen in ca. 6 mm starke, rundliche Höcker aufgelöst. 15-20 Randstachelborsten, weißlich bis bräunlichweiß, davon 3-4 als mittlere anzusehen, die längsten bis 1 cm lang. Blüte ca. 4 cm breit, goldgelb, Schlund weiß, doppelte Blütenblätterreihe. Röhre mit grünlichrot gespitzten Schuppen. Frucht beborstet, nicht sehr groß, Samen matt und braunschwarz. Vorkommen: Salta, bei 2800 m (N.-Argentinien).

English translation

Forming groups, dark green, usually tinged with red, the areoles with scanty brown wool. Rips broken up into roundish tubercles ca. 6 mm across. Radial spines 15-20, white to brownish white, 3-4 of them to be regarded as central,
the longest up to 1 cm long. Flowers ca. 4 cm across, golden yellow, throat white, the floral leaves in two series. Tube with greenish red, pointed scales. Fruit bristly, not very large, seeds dull brownish black. Occurrence: Salta, at 2800 m. (N.-Argentina).