Rebutia
Rebutia in Monatsschr. Kakteenk. 5: 102. 1895 sec. Ritz & al. 2007
- Type: Rebutia minuscula
Notes
Phylogenetics: The circumscription of Rebutia s.l. vs. a suite of proposed segregates (including Aylostera, Digitorebutia, Mediolobivia, Sulcorebutia and Weingartia) has been the subject of continued debate in the past 30 years. The wide circumscription (including these taxa) was adopted by Anderson & al. (2001) and Hunt (2006), but not by Anderson (2005) who recognized Sulcorebutia and Weingartia. The broad concept goes back to the consensus Cactaceae classification as summarized by Hunt & Taylor (1986), and some participants of the discussions at that time even argued that Rebutia sensu latissimo should be placed in the synonymy of an even more expanded Echinopsis.
Recent molecular phylogenetic studies showed, however, that Rebutia does not belong into the Echinopsis clade (Ritz & al. 2007; Mosti & al. 2011; Schlumpberger & Renner 2012), and that the genus in this broad concept is an untenable polyphyletic assemblage. In the molecular phylogeny of Ritz & al. (2007), three independent clades with taxa of Rebutia s.l. are found, namely Weingartia (incl. Sulcorebutia and Cintia), "Rebutia I" (including the segregates Aylostera, Digitorebutia and Mediolobivia), and "Rebutia II" (conforming to Rebutia s.str.). While Rebutia s.str. is placed as sister to Browningia, Aylostera is placed in a clade with Cereus and Stetsonia (Ritz & al. 2007; Mosti & al. 2011). Therefore it appears reasonable to abandon the concept of Rebutia s.l., to restrict Rebutia to the "true" rebutias, and to accept both Aylostera as well as Weingartia as separate genera. Most of the necessary new combinations have been published for Aylostera (Monti & al. 2011) and Weingartia (Hentzschel & Augustin 2008).A
Recent molecular phylogenetic studies showed, however, that Rebutia does not belong into the Echinopsis clade (Ritz & al. 2007; Mosti & al. 2011; Schlumpberger & Renner 2012), and that the genus in this broad concept is an untenable polyphyletic assemblage. In the molecular phylogeny of Ritz & al. (2007), three independent clades with taxa of Rebutia s.l. are found, namely Weingartia (incl. Sulcorebutia and Cintia), "Rebutia I" (including the segregates Aylostera, Digitorebutia and Mediolobivia), and "Rebutia II" (conforming to Rebutia s.str.). While Rebutia s.str. is placed as sister to Browningia, Aylostera is placed in a clade with Cereus and Stetsonia (Ritz & al. 2007; Mosti & al. 2011). Therefore it appears reasonable to abandon the concept of Rebutia s.l., to restrict Rebutia to the "true" rebutias, and to accept both Aylostera as well as Weingartia as separate genera. Most of the necessary new combinations have been published for Aylostera (Monti & al. 2011) and Weingartia (Hentzschel & Augustin 2008).A
Taxon standing
Category B. The genus is monophyletic based on phylogenetic studies that support the clade based on a sufficiently dense or even complete sampling, or support a monotypic genus as a distinct lineage, but do not provide a new taxonomic treatment at the species level. In many cases, older classical taxonomic synopses or a monographic treatment exist for these genera providing a reliable assessment of the species included.
Bibliography
A. Hernández-Ledesma, P., Berendsohn, W. G., Borsch, T., von Mering, S., Akhani, H., Arias, S., Castañeda-Noa, I., Eggli, U., Eriksson, R., Flores-Olvera, H., Fuentes-Bazán, S., Kadereit, G., Klak, C., Korotkova, N., Nyffeler, R., Ocampo, G. & Ochoterena, H. 2015: A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales. – Willdenowia 45(3): 281-383