Rebutia (Aylostera) cajasensis was first published in the Dutch journal Succulenta 56(3): p. 64 by Friedrich Ritter in 1977.

The original description in Latin is given here, together with my own English translation. However you should look up the original for more details including notes in Dutch. Note that the description was made of a plant which was not in flower.

Rebutia cajasensis Ritter spec.nov.

Solitaria, globosa, 3 cm crassa, radice rapacea; costae ca. 18, dissolutae tuberculis 2,5 mm altis; areolae oblongae, lana brunneola exigua obtectae, 1-1,5 mm diam., 2-3 mm inter se remotae; spinae rectae, asperae; marginales 10-11, lateraliter directae, 2-3 mm longae, flaveolae, postea albae; centrales 1-3, robustiores, brunneae, 3-5 mm longae; Flores ignoti.

Fructus 5-7 mm longus, 4-5 mm crassus, superne angustus, pallide violaceus, squamis 0,5-1 mm longis, lana exigua alba et interdum 1 saeta instructus.

Semina 0,8 mm longa, 0,6 mm crassa, atra, tenuiter tuberculata.

Habitat Cajas, Prov. Mendez, Bolivia.

Nr. collect. FR 1141

English translation

Rebutia cajasensis Ritter spec.nov.

Solitary, spherical, 3cm thick, tap-rooted, around 18 ribs, split into tubercles 2.5mm high; areoles oblong, 1- 1.5mm in diameter, 2 – 3mm apart, with some brown wool; spines erect, rough; 10 – 11 marginal spines, spreading laterally, 2 – 3mm long, yellowish, later white; 1 – 3 central spines, brown, stronger, 3 – 5mm long; flowers not known.

Fruit 5 – 7 mm long, 4 – 5mm thick, narrowing at the top, light purplish, with 0.5 – 1mm long scales, a little white hair and sometimes a bristle.

Seed 0.8mm long, 0.6mm thick, black, somewhat bumpy.

Habitat: Cajas, Prov. Mendez, Bolivia.

Collection number: FR 1141