Rebutia (Aylostera) donaldiana was described in Ashingtonia 1:7, pp. 76-78, in 1974 by Alfred Lau and Gordon Rowley. The description is comprehensive and quite lengthy, in the traditional Latin but also considerably expanded in English, and includes photographs, drawings, and an entertaining account of the discovery.

Here is a brief excerpt of the main points of the description, in the original Latin with an abridged English translation. You should look up the original description for more details.

Rebutia donaldiana Lau et Rowl. sp. nov. Subgenus Aylostera (Back.) Buin. et Don. Sectio Aylostera (Back.) Buin. et Don.

Corpus globosus vel brevicylindricus radicibus fusiformibus, ad 80 mm crassus et 100 mm altus, atroviridis, libere caespitosus, Areola ovata, fulvolanata, 10 mm distans, 4mm longa, 2.5 mm lata, in apice tuberculae in sul-a brevi posita. Spinae bulbosae; radiales superae 5-7, fulvae, ad 15 mm longae, plus minusve radiatim patulae; radial es inferae 5, 5-10 mm longue, albae, albae, breviores, tenuiores; centrales 4-6, 20-25 mm longae, subulatae, atrocastaneae, una descendentes, ceterae ascendens. Flores tu bis longis angustique, 15-20 mm. longis et 2.5 mm. latis; tepalibus spatulatis, aurantiacis, 10-15 mm. longis, 3-4 mm. latis; filamentibus albis. Stylus albus, basaliter per 10 mm. receptaculo connatus, stigmate albo, 6-lobato Fructus bacca olivacea, 5-6 mm.diametro, capillis albis et setis in axillis squamarum armatus. Semina nigra, c. 1 mm longa, 0. 75 mm lata, galeiformes; testa papillata et hilo basali subelevato ut in type R. fiebrigii.

Habitus in vicino Pucara, Dept. Santa Crus, Bolivia a 2400 m., rarus, in fissuris rupibus granitibus.

Holotypus HE I, in Herb. Univ. Heidelbergensis sub numero Lau 348 depositus.

English translation

Rebutia donaldiana Lau et Rowl. sp. nov. Subgenus Aylostera (Back.) Buin. et Don. Sectio Aylostera (Back.) Buin. et Don.

Body deep green, deeper green on tubercles, glossy, globular to short cylindrical, freely caespitose forming clumps with heads up to 80 mm diameter and 100 mm high; 16-18 spiralled rows of conical tubercles 4mm x 5mm at base and 4mm high near the shoulders, flatter & broader near base of plant. Roots fusiform.

Areole oval, 4mm long by 2.5mm wide, brown felted, centrally placed on apex of tubercle in a shallow groove; 10mm apart. All spines with thick globular bases. 10-12 radials, the 5 lowest shorter and thinner, 5-10 mm long, white; the remainder (5-7) brown, up to 15mm, mostly radiating upwards and outwards; 4-6 centrals 20-25mm long, awl-like, deep chestnut brown, one downwards and others upwards. New spines bicoloured, basal 5mm yellow then chestnut brown.

Flower bud from uppermost part of groove on mature areoles, rounded, deep crimson purple with white tomentum; pericarp 4mm diameter, pinkish olive, with minute olive green triangular scales and white hairs in the axils; tube slim, narrow, dull pinkish orange, 15-20mm long and 2.5-3mm thick, bearing small lanceolate pale greenish yellow scales and white hairs in the axils; bracteoles narrow lanceolate, mauve on underside, dull orange on upperside; outer and inner perianth similar, spathulate, pure orange, 10-15mm long and 3-4mm wide; throat white; filaments, 5-l0mm long, inserted apparently only in the top half of the receptacle, white with white anthers & yellow pollen grains. Style white, 25-30mm long, partly occluded for the lowest 10mm within receptacle; nectary rudimentary and without apparent nectar and scentless; stigma lobes 6, white, spreading, 2-5mm long.

Fruit an olive-green berry with small triangular scales bearing white hairs and bristles, 5-6mm in diameter. Seed black, helmet-shaped with papillate rugose testa and oval, 1.5mm x 1 mm, slightly raised basal hilum characteristic of the Bolivian aylosteras of the R. fiebrigii group.

Habitat Pucara, Dept. Santa Cruz, Bolivia at 2400m in crevices in steep granite rocks facing north. Extremely local in distribution.

Holotype HEI Lau 348.