Rebutia xanthocarpa description

Rebutia xanthocarpa was discovered by C. Backeberg in Salta, Jujuy, Argentina and first described in Der Kakteenfreund 1, p. 131, by C. Backeberg in 1932. I have been unable to locate a copy. However the description was re-published by Backeberg three years later, in Backeberg, C. & Knuth, F. M. (1935), Kaktus ABC, pp. 278-9 & 416. Gyldendalske Boghandel-Nordisk Forlag, Copenhagen, Denmark.

Here is the text of the description in the original Latin with my own English translation below, together with a few additional notes extracted from the Danish section. You should look up the original for more details in Danish and a black-and-white photograph.

Rebutia xanthocarpa Bckbg. sp. n.

Pallide viridis, ad 5 cm diametro, aculeis ad 5 mm longis, tenuibus, sordide vitreo albidis; flore parvo, ad 2 cm longo, campanulato, rubro, ovario luteo. — Argentina: Salta, alt. ca. 2500 m.

English Translation

Rebutia xanthocarpa Bckbg. sp. n.

Pale green, up to 5cm in diameter, spines up to 5mm long, thin, dull white, translucent; flowers small, up to 2cm long, bell-shaped, red, ovary yellow. Salta, Argentina, alt. ca. 2500m.

Additional notes

Backeberg states that this differs from Rebutia senilis in having smaller flowers and pale yellow, greenish or orange fruits. He goes on to describe 5 varieties:

Var. 1. citricarpa Bckbg. (Rebutia citricarpa Fric): almost minuscula-like plant with short spines and greenish-yellow ovary.

Var. 2. coerulescens Bckbg .: luminous bluish-red [purplish?] flower; very beautiful, orange-yellow ovary.

Var. 3. luteirosea Bckbg .: yellow-pink flowers, pale.

Var. 4. salmonea Bckbg. (Rebutia salmonea Fric): pink to carmine pink Flowers, pale red ovary.

Var. 5. elegans Bckbg .: erect, quite faintly yellow-tipped spines; ribs more defined, spiralling; body short cylindrical.