Origin and Habitat: Northern Argentina (province of Salta) and Bolivia (Department of Tarija)
Altitude range: 2300-2500 metes above sea level.

• Rebutia hoffmannii Diers & Rausch
• Aylostera hoffmannii (Diers & Rausch) Mosti & Papini

• Rebutia fiebrigii (Gürke) Britton & Rose in L.H.Bailey & L.H.Bailey
• Aylostera fiebrigii (Gürke) Backeb. in Backeb. & F.M.Knuth
• Echinocactus fiebrigii Gürke
• Echinorebutia fiebrigii (Gürke) Frič & Kreuz.
• Rebutia albipilosa F.Ritter
• Aylostera albipilosa (F.Ritter) Backeb.
• Rebutia archibuiningiana F.Ritter
• Aylostera archibuiningiana hort.
• Aylostera fiebrigii var. archibuiningiana hort. sensu D.R.Hunt
• Rebutia buiningiana F.Ritter non Rausch
• Rebutia spinosissima var. archibuiningiana hort. sensu Pilbeam, E.F.Anderson
• Rebutia cajasensis F.Ritter
• Aylostera cajasensis (F.Ritter) Mosti & Papini
• Rebutia cintiensis F.Ritter
• Aylostera cintiensis (F.Ritter) Mosti & Papini
• Rebutia donaldiana A.B.Lau & G.D.Rowley
• Aylostera donaldiana (A.B.Lau & G.D.Rowley) Mosti & Papini
• Rebutia fiebrigii var. azurduyensis (J.de Vries)
• Aylostera azurduyensis J.de Vries
• Aylostera fiebrigii var. azurduyensis (J.de Vries) Mieczak.
• Rebutia azurduyensis (J.de Vries) hort.
• Rebutia fiebrigii var. densiseta (Cullmann) Oeser
• Rebutia fiebrigii f. densiseta Cullmann
• Rebutia fiebrigii var. vulpes F.Ritter
• Rebutia flavistyla F.Ritter
• Aylostera flavistyla (F.Ritter) Mosti & Papini
• Rebutia hoffmannii Diers & Rausch
• Aylostera hoffmannii (Diers & Rausch) Mosti & Papini
• Rebutia ithyacantha (Cárdenas) Diers
• Mediolobivia ithyacantha Cárdenas
• Rebutia jujuyana Rausch
• Aylostera jujuyana (Rausch) Mosti & Papini
• Rebutia kieslingii Rausch
• Aylostera kieslingii (Rausch) Mosti & Papini
• Rebutia lateritia n.n.
• Aylostera lateritia n.n.
• Rebutia muscula F.Ritter & Thiele
• Aylostera muscula (F.Ritter & Thiele) Backeb.
• Rebutia pulchella Rausch
• Aylostera pulchella (Rausch) W.Haage
• Rebutia pulchella var. prolifera Rausch
• Aylostera pulchella var. prolifera hort.
• Rebutia simoniana Rausch
• Aylostera simoniana (Rausch) Mosti & Papini
• Rebutia sp. Huari Huari
• Rebutia spinosissima Backeb.
• Aylostera spinosissima Backeb. in Backeb. & F.M.Knuth
• Rebutia tamboensis F.Ritter
• Aylostera tamboensis (F.Ritter) Mosti & Papini
• Rebutia vallegrandensis Cárdenas
• Aylostera pumila A.B.Lau, n.n.
• Aylostera vallegrandensis (Cárdenas) Mosti & Papini
• Rebutia walteri Diers
• Aylostera walteri (Diers) Mosti & Papini

Description: Rebutia hoffmanniiSN|5049]]SN|5054]] (Aylostera hoffmanniiSN|25460]]SN|25460]]), is generally included within (as a synonym of) Rebutia spinosissimaSN|5054]]SN|5049]], suggesting that there is not really a fundamental difference between the two. At the same time Rebutia spinosissimaSN|5049]]SN|5049]] is now considered one of the morphological form of the widespread and variable e Rebutia spinosissimaSN|5049]]SN|5049]], that together with other closely related taxa form a special group within R. fiebrigii differentiated by spination and smaller, flatter, strongly tuberculate stem that makes them easy to recognize. Spines are dense, fine, bristle-like, numerous, hardly distinguishable as central and radial. Rebutia hoffmanniiSN|5049]]SN|5054]] is not exactly identical to Rebutia spinosissimaSN|5054]]SN|5049]], but distinguish from the latter by denser, very fine, tight, white spines, usually with brownish tips, that add more colour to the plant and outer petals often with purple-reddish shades. The flowers are also small for the genus.
Stems: Solitary later forming cushions, the individual stems rather flat to spherical, up to 40 mm wide, light green, crown somewhat depressed, filled with spines.
Ribs: About 25, low, divided in small conical tubercles.
Areole: Closely set, round, about 1.5 mm wide, whitish to brownish tomentose.
Spines: Numerous, fine, bristle-like, hardly distinguishable as radial and central, whitish. Central spines 5-6 somewhat stronger and longer, with brownish tip. Radial spines fine whitish to 10 mm long.
Flowers: Light brick-red, darker inside, funnel-shaped, about 30 mm long and 25-30 mm wide. Ovary c. 3 mm wide, pale olive green, covered with white triangular scales, with 3 mm long, thin, flexible, twisted, white bristles and hair in their axils. Floral tube slender cylindrical, about 10 mm long and 3 mm wide, pale greenish, covered with 1-2 mm long scales. Outer perianth segments, lanceolate with sharply pointed tip, 5-15 mm long and 1-4 mm wide, the smallest (lowermost) pale greenish, the larger with orange median stripe and purple-reddish tips. Inner perianth segments c.10 mm long and 5 mm wide, brick red with vermilion red middle stripe. Filaments white, thin, 6-10 mm long, anthers small, spherical, yellow. Pistil white, thread-like, fused with the base of the tube for about 5 mm, with 5-6 stigma lobes about 3 mm long.
Fruit: Small, spherical, 3-4 mm wide, covered in scales, hair and bristles.
Seeds: Elongated, about 1 mm long.

Bibliography: Major references and further lectures
1) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
2) David Hunt “Cites Cactaceae Checklist” Third edition 2016
3) Backeberg, Curt; Knuth, Frederic Marcus; “Kaktus-ABC”, p. 275, 1935
4) Backeberg, Curt; “Die Cactaceae”, 3: 1531, 1959
5) Backeberg, Curt; “Das Kakteenlexikon”, p, 71, 1966
6) Donald, John Donald; “The Classification of the Rebutias”; Ashingtonia, 2, 1977
7) Krainz, Hans; “Die Kakteen”, 15: CVc, 1960
8) Pilbeam, John; “Rebutia”, p. 93, 1997
9) Šída, Otakar; “Atlas kaktusů”, tab. 42, 1995
10)Šída, Otakar; “Rod Rebutia”, p. 59, 1997

Cultivation and Propagation: Rebutia hoffmanniiSN|4948]]SN|5054]] is a summer grower species that is easy to cultivate and recommended for beginners. The whole Rebutia fiebrigiiSN|4932]]SN|4932]] complex has delightful flowers and the plants remain compact, and clumps can easily be managed by division. Another advantage is that the plants are cold hardy in winter if kept dry.
Growth rate: It is a slow growing but easily flowering species that will make clumps given the best conditions.
Soils: This species is easy to cultivate in a very open mineral mix with at least 50% sand or pumice grit and a pH slightly on the acidic side.
Repotting: It is better that they are repotted regularly. Pots should be only slightly larger than the plant and root system. Repotting will increase the number and size of stems, and will increase the number of flowers produced. Repot yearly until they reach about 100 mm in size, then every two or three years will suffice. Repotting is best done at the end of winter, but can be done at other times, too. Do not water for a couple of weeks after repotting, to reduce risk of root rot via broken roots. A layer of 'pea' gravel at the bottom of the pot improves drainage. A layer of decorative gravel as a top dressing helps prevent the caking of the potting mix, which decreases the rate of water absorption. It also keeps the perlite and pumice from blowing everywhere, and looks nice.
Watering: It requires full sun or light shade and careful watering to keep plant compact, and maintain strong and dense spines and allow the pot to dry out between waterings. Keep dry in winter at a minimum temperature of 0°C. Rebutia albipilosaSN|5054]]SN|4948]] tends to rot if too wet. The plants can be placed outdoors in April, but protected from rain and direct sunlight. Water them thoroughly when placed out, and again in two weeks, and again in one week. After one month the plants are ready to be placed out in full sun and full rain for the summer. During dry spells the collection is watered once a week, during hot dry spells, twice a week.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: It is reputedly resistant to frost if kept on the dry side prior to, and during, cold weather and requires a winter rest period (hardy to -7° C, or less for short periods). Rebutias grow in nature at high altitudes, and do not thrive well at high temperatures in cultivation. They will often go dormant in mid-summer, and resume growth again when the weather cools in late August. They can tolerate amazingly low temperatures for long periods of time. All species can take a frost, even when not bone dry. It is generally accepted that plants kept at too high a temperature, or watered too much during the winter rest period, will not bloom the following year. They will be perfectly happy in pots outdoors from April to September if protected from torrential rain and hail.
Exposition: The plant tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Tends to bronze in strong light, which encourages flowering and heavy spine production, but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer.
Uses: It is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame or outdoor in a rockery.
Pests & diseases: All, especially the young, are susceptible to red spider mites.
Rot: This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases. Rot it is only a minor problem with rebutias if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.
Propagation: Offsets, seeds. Seeds germinate in 7-14 days at 21-27° C in spring, remove gradually the glass cover as soon the plants will be well rooted (ca 1-2 weeks) and keep ventilated, no full sun for young plants! To make a cutting twist off a branch and permit it to dry out a couple of weeks, lay it on the soil and insert the stem end partially into the soil. Try to keep the cutting somewhat upright so that the roots are able to grow downward.
Note: It would appear that in cultivation they grow larger and cluster more vigorously than in habitat.