Rebutia (Aylostera) leucanthema was first described by Walter Rausch in Kakteen und andere Sukkulenten 26(6): p. 125, 1975, the journal of the Deutsche Kakteen-Gesellschaft.

Here is the description in Latin as published, followed by my own English translation. You should look up the original for more details including a photograph and further notes in German.

Rebutia (Aylostera) leucanthema RAUSCH spec.nov.

Walter Rausch

Simplex, globosa ad brevi-cylindrica, ad 7 cm alta et 3,5 cm diametiens, atroviridis ad violacea, radice napiformi; costis 13-14, spiraliter tortis, in gibberes 3-4 mm diametientes, verrucosus divisis; areolis ovalibus, 2-3 mm longis, fuscotomentosis; aculeis marginalibus 7-8, ad 6 mm longis, paulum ad corpus inflexis, fuscis. basi obscurioribus; aculeo centrali 0 – 1 , ad 7 mm longo, paulum sursum flexo, nigro.

Floribus lateralibus, 25 mm longis et diametientibus; ovario et receptaculo fusco-roseo, squamis angustis, fuscis, lana et setis albis tecto; phyllis perigonii exterioribus lanceolatis, roseis, medio-fusco-striatis; phyllis perigonii interioribus spathulatis, albis; fauce et filamentis albis, stylo (fere non connato) et stigmatibus (5-7) viridibus.

Fructu globoso, 5 mm diametiente, atroviolaceo, squamis clarioribus, pilis et setis albis tecto. Seminibus campanulatis
vel subelongatis, nigris, testa arillosa reliqua tectis, hilo magno basali.

Patria: Bolivia, Cinti septemtrionalis, Cana Cruz, 3.600 m alt.
Typus: Rausch 305 in Herbario Musei Historiae Naturalis Vindobonensi (Herbario W.)

English translation

Rebutia (Aylostera) leucanthema RAUSCH spec.nov.

Single, spherical to short cylindrical, up to 7 cm high and 3.5 cm diameter, with a tap root; ribs 13-14, arranged spirally, divided into 3-4 mm tubercles, with dark green to purple epidermis; areoles oval, 2-3 mm long, brown-felted; radial spines 7-8, up to 6 mm long, somewhat curved towards the body, brown with a darker base; central spines 0-1, up to 7 mm long, slightly curved upwards, black.

Flower appearing laterally, 25 mm long and the same diameter; ovary and tube brown-pink with narrow, dark brown scales, white wool and bristles; outer petals lanceolate, pink with brown central stripes; inner petals spatulate, white; throat and stamens white, style (almost unfused) and stigmas (5-7) green.

Fruit spherical, 5 mm diameter, black-violet with lighter scales, white hairs and bristles. Seed bell-shaped or somewhat elongated, black covered with remains of skin and large, basal umbilicus.

Habitat: Bolivia, Nor Cinti, Cana Cruz at 3600 m.

Type: Rausch 305 in the herbarium of the Natural History Museum of the City of Vienna, Austria.