The original description (of Rebutia rovidana) was published in the Italian journal Cactus & Co., 1 (9) 2005, pp. 215 to 221.
Here is an excerpt of the main points, but you should look up the full description for more details.
Rebutia rovidana Mosti & Papini sp. nov.
Typus – Holotypus: Argentina, Jujuy, near Tafna, WR 333b. Cult. S. Mosti, s. d. (FT)
A R. nazarenoensi Fearn & Pearcy differt areolis longioribus (2-3 mm vice 1-2 mm); aculeis longioribus sive marginalibus (1-1.2 cm vice 0.3-0.8 cm), sive centralibus (1.5-1.8 cm vice ad 1 cm) flexilibus nec rigidis; floribus majoribus (5 cm vice 3.5 cm diametientibus), segmentis perianthii lanceolatis nec rotundis, roseis neque aurantiacis, staminum filamentis roseis nec stramineis; seminum tegumento cellulis magis elongatis minusque prominentibus.
Habitus: solitary to scarcely offsetting.
Stems: brevicylindrical; dia. 3-4 cm, height 4-7 cm.
Epidermis: dark green, reddish brown at the base of the tubercles.
Tubercles: conical, rather evident; dia. 0.4-0.5 cm.
Areole: oval; l. 2-3 mm, with some light brown wool.
9-12; l. 1-1.2 cm; glassy white to cream-colour with darker apex, parallel to the stem or pointing slightly outwards.
Central spines: 1 (-2); l. 1.5-1.8 cm, rather flexible and sometimes curved in the central part; brown and slightly bulbous at the base, central part light brown, dark brown at the apex.
Flowers: l. 2.5-3 cm; w. 5 cm.
Flower tube: pinkish brown with dark brown scales.
Segments of the perianth: 25 ca., lanceolate and with short mucro; external segments of perianth pink or light brown with brown band of varying width; internal segments of perianth light salmon pink (darker on first day of anthesis) with central, more or less evident magenta stripe.
Filaments of the stamens: inferior half magenta pink, superior half salmon pink.
Style: l. 2 cm (connate for 0.5 cm), green.
Stigma: light yellow (7 lobes).
Fruit: dia. 0.7 cm; red-brown with thin but evident brownish green scales and hair.
Cells of seed testa: slightly elongated and slightly protrusive with, on the sides, tubular or compressed ridges that from the base reach top of the cell, sometimes partially revealing an apical zone with much finer and more tightly packed ridges.