The description of Rebutia wessneriana was first published in Sukkulentenkunde 2: p. 24, in 1948 by W. Bewerunge. The description is stated to be from material in cultivation owned by a Mrs. Winter in Frankfurt, from plants imported by Stümer or Marsoner; originally labelled Rebutia turbinata, but without location data.

Here is the text of the description in Latin, as published, with my own English translation below. You should look up the original for further details including additional notes in German, and a black-and-white photograph.

Depresso-globosa, ad 7 cm alta et 8 cm diametro, viridis, proliferans, vertice impresso, aculeisque non supertexta. Tubercula 2 mm alta. Areolae parvae, ca. 1,5 : 2 mm sublonguinosae, albide tomentosae. Aculei ca. 25, ad 20 mm longi, albi, superiores apice fuscati, non divaricantes. Flores ex media parte corporis usque ad verticem nascentes, ad 55 mm diametro, colore sanguinis; ovario tuboque rubra squamisque violaceis praeditis; stylo roseo stigmatibusque albidis; filamentis rubris antherisque aureis. Fructus seminaque ignota. Item patria.

English translation

Flattened, spherical, up to 7cm high and 8cm in diameter, green, branching, the top depressed, not covered by spines. Tubercles 2mm high. Areoles small, ca. 1.5 – 2mm, slightly elongated, with whitish felt. Ca. 25 spines, all similar, up to 20mm long, white, upper ones brownish near the tips. Flowers borne from the middle of the body to the crown, up to 55mm wide, blood-red; ovary and flower tube red, covered with purplish scales; style pink with white stigmas; stamens red with gold anthers. Fruit, seed and habitat not known.