In July 2011, we were in Bolivia in the Rio Grande Valley, between the departments of Chuquisaca and Santa Cruz to study Espostoa guentheri (Kupper) Buxbaum, to evaluate how these populations were close, at an olomorphological level, to Espostoa Britton & Rose, as proposed by Hunt et al., even if they highlight a separation in the distribution area compared to the rest of the group (2006, text: 116), rather than Vatricania Backeberg, reintroduced by recent molecular studies (Lendel et al. 2006, umpubl. data in Nyffeler & Eggli 2010). At the time, we would not have thought that there might be another answer, a third, as clearly emerges from the molecular studies, even more recent and complete (Schlumpberger & Renner 2012). From these studies it appears that Espostoa and Vatricania and other genera of the tribe Trichocereeae (Anderson 2001, 2005, 2011; Hunt et. Al 2006) or subtribe Trichocereinae (Nyffeler & Eggli 2010), together with the species included in the current idea of Echinopsis sensu lato (Anderson 2001; 2005; 2011; Hunt et al. 2006), constitute a unique well supported monophyletic clade in Echinopsis (100% bootstrap support). This would replace the current clade, which has proved to be highly polyphyletic. Returning to the Rio Grande Valley, the observations on the morphology of the cephalium, in all specimens viewed of E. guentheri, have highlighted that none of them shows the character that, according with Backeberg (1966, 789, fig. 444), distinguishes Vatricania from Espostoa, i.e. the superficial cephalium that completely surrounds the upper part of the stem. What happens to the specimen in the greenhouse, shown in the Backeberg’s photo, cannot be found in nature. In old plants, at the apex, the cephalium may involve a few more ribs than the centre of the stem (photo 14), but on average in mature specimens, the cephalium occupies about half of the ribs. For example in the stem of the photos 33-34, the cephalium at the apex includes 11 of 22 ribs, and going down it becomes narrower until it includes 7 of 22. Therefore, the distinction between Espostoa and Vatricania, does not lie in the form or in the dimension of the cephalium. For the definition of the taxon, taking into account the molecular results highlighted by Nyffeler and Eggli (2010), data reinforced by the separation of the distribution areas of the two genera, we were considering opting for Vatricania but as mentioned before, the results by Schlumpberger & Renner (2012) have been illuminating. In this aspect, we had no difficulty in interpreting Cleistocactus Lemaire, Denmoza Britton & Rose, Oreocereus (A. Berger) Riccobono, or Weberbauerocereus Backeberg as possible Echinopsis, with floral characters and / or pollination syndromes modified. For example, we consider that Denmoza rhodacantha (Salm-Dyck)) Britton & Rose is clearly a perfect link between the current concept of Echinopsis sensu lato (Anderson 2001, 2005, 2011; Hunt et. al 2006) and the genera that the study by Schlumpberger & Renner (2012) add in order that the genus Echinopsis can really be monophyletic (for more details about our position see cactusinhabitat booklet. South America 2011-2013 (Anceschi & Magli 2013b, 22-29). It is remarkable that, in the ontogenesis of the new named Echinopsis guentheri (Kupper) Anceschi & Magli, some juvenile phases are identified (before the emergence of the cephalium) (photos 6-8, 25-26), in which the taxon is morphologically close to certain Andean Echinopsis (Trichocereus). Moreover, coming to define the taxon as an Echinopsis, the question of geographical isolation loses its meaning. The phytogeographical area of E. guentheri is a niche in the Chaco Biome that remains isolated in the first Andean mountains. This is demonstrated by the cacti which live sympatrically with it: Cereus stenogonus K. Schumann, Castellanosia caineana Cárdenas, Gymnocalycium pflanzii (Vaupel) Werdermann, Neoraimondia herzogiana (Backeberg) Buxbaum & Krainz, Echinopsis bridgesii Salm-Dyck; all taxa characteristic of the Chaco, with the exception of E. bridgesii. Between the columnar cacti that populate the Chaco, one of the major ecosystems of the South American continent (of approximately 1,000,000 square kilometers), it seemed that there wasn’t any kind of Echinopsis, but now we think that a possible descendant of the Andean Trichocereus stopped in the Rio Grande Valley. (Quoted from: Anceschi & Magli 2013b, 47-48)

Echinopsis guentheri (Kupper) Anceschi & Magli is a new combination published in cactusinhabitat booklet. South America 2011-2013 (Anceschi & Magli 2013, 38). For the phylogenetic hypothesis adopted for the assimilation of Vatricania Backeberg in Echinopsis Zuccarini see booklet (ibid., 22-29). (June 2013)