Rebutia (Aylostera) tamboensis was first described by Friedrich Ritter in Ashingtonia vol. 2: 10, p. 207, the journal of the Ashington Botanical Trust, in 1977.

Here is the text in Latin as published, together with Ritter’s own English translation, but you should look up the original for further notes and a black-and-white photograph. Note that the number of ribs described in the Latin version is 20, while in the English version it is 26.

REBUTIA tamboensis Ritter, spec. nov.

Solitaria, globosa, clare viridis, ad 6 cm crassa; costae ca. 20, fere dissolutae tuberculis 4-6 mm altis; areolae oblongae, 3-4 mm longae, lana alba copiosa obtectae, 3-4 mm inter se remotae; spinae non asperae, marginales 12-18, albae, tenues, lateraliter directae, 5-10 mm longae; centrales 4-6, robustiores, 15-25 mm longae, rutilae basi alba; flores 16-20 mm longi; ovarium lana alba et saetis albis instructum; stylus 5-6 mm cum tubo connatus; sulcus nectarifer 0.5 mm longus; tubus floralis 2 cm longus, roseopurpureus, lana alba et saetis fere usque ad oram instructus; filamenta alba, biseriata; stylus albus; stigmata 6, flaveola; petala 8-10 mm longa, 3.5-4 mm lata, spathulata, miniata ad coccinea; fructus atroviridis, pulpa rubra; semina atra, 1.4 mm longa, 0.8 mm lata, tenuiter tuberculata; habitat in principio faucium Tambo, Prov. O’Connor, Bolivia. Collected under FR. 1142.

English translation

Solitary, globular, bright green to 6 cm wide; ribs about 26 broken into disorganised tubercles 4-6 mm high; areoles oblong: 3-4 mm long, copiously covered with white wool, 3-4 mm apart; spines not stiff, radials 12-18, white, thin, in all directions, 5-10 m long; centrals 4-6, more robust, 15-25 mm long, red with white base; flowers 16-20 mm long; ovary covered with white wool and bristles; style 5-6 mm with inclined tube; nectary groove 0.5 mm long; flower tube 2 cm long, rose-purple, covered with white wool and bristles just up to the margin; filaments white, in two series, style white; stigma lobes 6, yellowish; petals 8-10 mm long, 3.5-:i mm wide, spathulate, red to scarlet; fruit dark green, pulp red; seeds black, 1.4 mm long, 0.8 mm wide, finely tuberculate; habitat in the main pass in Tambo, Province O’Connor, Bolivia. Collected under FR. 1142.