The description of Rebutia krainziana was first published in Sukkulentenkunde 2: pp. 23-24, in 1948 by W. Kesselring.

Kesselring states the description is of material collected by Mrs. Ritter and introduced by the nurseries Winter in Frankfurt and Kaktus A.G. in Reinach.

Here is the text of the description in Latin, as published, with my own English translation below. You should look up the original for further details including additional notes in German.

Rebutia Krainziana Kesslrg. spec. nov.

Von W. Kesselring, Darmstadt

Caulis plerumque plane-globosus, rarius subcolumnaris, prolifer et saepe aggregatus, ca. 4—5 cm altus, ca. 3—4 cm latus, opace-viridis; vertex late impressus; costae valde Spiralen, in parte centrati turbinatae, in mammillas solutae; areolae albo-lanosae, magnae, plerumque ovales, ca. 2 mm longae, rarius rotundatae, ca. 3—4 mm remotae; aculei setosi 8—12 plerumque adpressi, quorum nonnulli raro oblique sursum patentes; flores numerosi, ca. 3 cm longi, ca. 4 cm lati, rubro-vel atro-rubro marginati, medium versus subviolacei, micantes, basi luteoli; filamenta luteo-alba antheris flavidis; stylus stigmatibus 10 lateolo-alba. Fructus seminaque ignota.

Patria: Bolivia, locus accuratius indicatus ignotus.

English translation

Rebutia Krainziana Kesslrg. spec. nov.

W. Kesselring, Darmstadt

Body flattened-spherical, rarely short cylindrical, clustering, stems 4 – 5cm high and 3 – 4cm wide, dull green; tops widely depressed; ribs strongly spiraling, broken into bumps [tubercles] twisting into the centre like a turbine; areoles with white wool, large, generally oval, rarely circular, ca. 2mm long, with 3 – 4mm between each; 8 – 12 bristly spines, generally adpressed against body, occasionally a few obliquely upwards; numerous flowers, ca. 3cm long and 4cm wide, red to dark red in the margins with a purplish shining central line and a yellowish base; stamens yellowish-white, anthers yellow; style and 10 stigmas yellowish-white. Fruit and seeds not known.

Habitat: Bolivia, accurate location not known.