Rebutia margarethae was first described by Walter Rausch in Kakteen und andere Sukkulenten 23(1): pp. 4 – 5, 1972, the journal of the Deutsche Kakteen-Gesellschaft.

Here is the text of the description in Latin as published, together with my own English translation below. You should look up the original for more details in German and a colour photograph.

Rebutia margarethae Rausch spec. nov.

Von W. Rausch

Simplex, ad 4 cm alta et 6 cm diametiens, violaceofusca, radice rapiformi ; costis 15—17, spiraliter tortis, in gibberes ca. 10 mm longos, rotundos dissolutis; areolis ovalibus ad elongatis, ca. 3 mm longis, albotomentosis; aculeis marginalibus 7—11, 15—20 mm longis, divaricatis ad accumbentibus; aculeo centrali 1, ad 30 mm longo; aculeis omnibus saepe subarcuatis, brunneis basi flavis, postea canescentibus.

Floribus lateralibus ad basalibus, ca. 40 mm longis et 35 mm diametientibus; ovario et receptaculo flavido-roseo, squamis nudis, viridibus tecto; phyllis perigonii exterioribus roseis medio-viridi-striatis; phyllis perigonii interioribus spathulatis, rubris, intus aurantiacis; fauce et filamentis flavis, stylo paululum cum receptaculo connato, albo, stigmatibus 6, albis. Fructu plano-globoso, ca. 4mm diametiente, subfusco-flavo, squamis roseis ad viridibus tecto, glabro. Seminibus mitraeformibus, 1,3 mm longis et 1 mm diametientibus, testa longe-verrucosa, nigra et hilo magno, basali, albo.

Patria: Argentina, Salta apud Santa Viktoria, 3500 m alt.

Typus Rausch 521 in Herbario W .

English translation

Rebutia margarethae Rausch spec. nov.

W. Rausch

Single bodied, up to 4cm high and 6cm in diameter, purplish brown with a tap root; 15 – 17 ribs spiralling, broken up by round tubercles ca. 10mm long; areoles elongated oval, ca. 3mm long, with white wool; 7 – 11 marginal spines, 15 – 20mm long, spreading and flattened; 1 central spine, up to 30mm long; all spines often slightly curved, brown with a yellowish base, later greyish.

Flowers arising from the base to the sides, ca. 40mm long and 35mm in diameter; ovary and receptacle yellowish-pink, with greenish hairless scales; outer petals pink with a greenish central stripe; inner petals spatulate, red with orange inside; throat and stamens yellow, style a little fused with the tube, white, with 6 white stigmas. Fruit flattened spherical, ca. 4mm in diameter, brownish-yellow, with pink to greenish scales, hairless. Seeds mitre-shaped, 1.3mm long and 1mm wide, the black skin with longitudinal warts and a large white navel.

Habitat: Above Santa Victoria, Salta, Argentina, at 3500m alt.

Type: Rausch 521 deposited in the Herbarium of the Natural History Museum of the City of Vienna, Austria.