Rebutia (Aylostera) spinosissima was first described by C. Backeberg in Blatter Fur Kakteenforschung (Bulletin of Cactus Research) 2(8): p.8, together with a black-and-white photograph, in 1935.

Here is the text of the description in the original very brief Latin with a little more detail in German, together with Backeberg’s own English translation. You should look up the original for more details.

REBUTIA SPINOSISSIMA Bckbg. n. sp.

Subplana ad 4cm diam. saepe proliferans; areolae densae, aculei setosi, nu-claro-miniati; tubus setulosus.

Polster bildend, flach, Einzelkörper hellgrün, bis 4 cm und Höhe. Scheitel leicht eingesenkt. Areolen sehr dichtstehend, ca. 11,5 mm groß, weißlich befilzt. Zahlreiche Rand- und Mittelstacheln, borstenförmig, weißlich, die mittleren 5-6 stärker, hornfarbig, braun gespitzt, stark in der Farbe variierend.

Blüten hell backsteinrot, bis 3 cm Durchmesser, gelbgrüne Röhre, schwach behaart. Staubfäden weiß, Narben weiß, 6. Stempel mit Röhre verwachsen.

Frucht sehr klein.

Vork. Salta (N.-Argt.) 2500 m ü. M.

English translation

REBUTIA SPINOSISSIMA Bckbg. n. sp.

Forming cushions, low, single bodies pale green, up to 4 cm across and high. Crown slightly depressed. Areoles very close, ca. 1.5 mm across, with white hair. Numerous radial and central spines, bristle-like, whitish, the central 5-6 stronger, horn-coloured, brown tipped, varying greatly in colour. Flowers pale brick red, up to 3 cm diam., tube yellowish green, slightly hairy. Stamens white, stigmas white, 6. Pistil united with the tube. Fruit very small. Occur Salta (N. Argentina) at 2500 m.