Rebutia

Historical limits of the genus

There has been considerable debate about the extent of the genus. In the middle of the twentieth century there was a tendency to separate groups of plants within Rebutia as new genera, e.g. Mediolobivia, whereas towards the end of the century the reverse tendency predominated, with genera previously regarded as separate, such as Weingartia, being subsumed within Rebutia. At the beginning of the twenty-first century there was a broad consensus, as reflected in Kew's list of Vascular Plant Families and Genera, that the following genera should be regarded as synonyms of Rebutia:^[5]

(The generic names Bridgesia, Spegazzinia, Echinorebutia, Eurebutia, Mediorebutia, Neogymnantha and Setirebutia are invalid, the first two because they are homonyms of Bridgesia Bert. ex Cambess. and Spegazzinia Backeb. respectively,^[6] the remainder for lack of any valid publication. Some of these are nevertheless valid names for subdivisions of the genus.^{[citation needed]})

The history of the taxonomic treatment of the genera Rebutia, Aylostera, Weingartia, Sulcorebutia and Cintia is summarized below.^[7]

The variation in the treatment of the genus is illustrated by the difference between Anderson in 2001, who synonymized genera including Aylostera and Weingartia with Rebutia, thereby creating a genus with as many as 41 species, and Mosti et al., who in 2011 separated Aylostera and Weingartia (including Cintia and Sulcorebutia) from Rebutia.^[7] As of December 2022^[update], Plants of the World Online agreed with Mosti et al. in keeping Aylostera separate,^[8] and also merged Cintia and Sulcorebutia into Weingartia,^[9] resulting in Rebutia having only three species.^[1]

Phylogeny

Molecular phylogenetic studies showed that when broadly circumscribed, the genus Rebutia was polyphyletic. Sulcorebutia and Weingartia were kept as separate genera in a 2007 study whose summary cladogram for those species studied is shown below.^[10]

Species formerly classified as Weingartia, Sulcorebutia and Cintia showed a close relationship to each other and to species of Rebutia with naked pericarpels (Rebutia II above), including the type species R. minuscula. The larger group of species of Rebutia studied, those with hairy or bristly pericarpels, formed a separate, more distantly related clade (Rebutia I). It was suggested that these be excluded from the genus,^[10] and as of December 2024^[update], Plants of the World Online placed them in the genus Aylostera.^[8]

Species

The number of species has been debated, because of disagreement both over what constitutes the genus and what constitutes a species. A very large number of plants that have circulated as species of Rebutia are now generally regarded as varieties, forms or synonyms of others.^[11] E. F. Anderson recognised 41 species in 2001.^[12] Only the following three species were accepted by Plants of the World Online as of December 2024^[update].^[1]

More information Image, Scientific name ...

Image	Scientific name	Distribution
	Rebutia fabrisii Rausch	Argentina
	Rebutia minuscula K.Schum.	Argentina
	Rebutia padcayensis Rausch	Bolivia to Argentina (Salta)

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