Note: For a number of years, molecular analysis has revealed the close relationship between Echinopsis s.l. and the other genera within the tribe Trichocereeae, or subtribe Trichocereinae (Nyffeler 2002, 317- 319; Schlumpberger 2009; Lendel et al. 2006, unpubl. data in Nyffeler & Eggli 2010). Even the more recent molecular analysis of Echinopsis (Schlumpberger & Renner 2012) has clearly demonstrated that a cladistically correct interpretation of the molecular data, in the direction of a monophyletic genus Echinopsis, leads to the assimilation in Echinopsis s.l., as currently conceived (Anderson 2001; Hunt et al. 2006; Anderson & Eggli 2011), of Cleistocactus Lemaire, Denmoza Britton & Rose, Haageocereus Backeberg, Harrisia Britton, Oreocereus (A. Berger) Riccobono, Weberbauerocereus Backeberg and 10 other genera of the Trichocereeae/Trichocereinae. We've dealt extensively with the subject, in the part devoted to the taxonomy in our penultimate booklet (Anceschi & Magli 2013b, 22-29). Our position is summarized in “The new monophyletic macro-genus Echinopsis. No risk of paraphyly, and the most convincing hypothesis in phylogenetic terms” appeared on Cactaceae Systematics Initiatives N° 31, pages 24-27 (August 2013).
Note: Without being able to rely either on the floral characters nor on the fruits, on the basis of the other available morphological characters, it is not possible to distinguish Echinopsis decumbens (Vaupel) Mayta from Echinopsis sextoniana(Backeb.) Mayta. On the difficult distinction between the two taxa in question, see also Mauseth et al. (2002, 174, regarding Loxanthocereus and Haageocereus) and especially Ritter (1981, 4: 1472), as Loxanthocereus sextonianus and Haageocereus decumbens). For these reasons, the surveys A&M 1139, A&M 1145, A&M 1156 and A&M 1157, carry the caption "Echinopsis decumbens or Echinopsis sextoniana".
July 2021
In August 2013, following publication of our 2011/2013 booklet (June 2013), we published an article relating to the discussed monophyly of Echinopsis Zuccarini s.l. in Cactaceae Systematics Initiatives (2013b, 31: 24-27). That article summarized and underlined the position we have taken in the booklet in relation to the phylogenetic hypothesis to be adopted regarding the classification of the genera related to Echinopsis s. l., within the tribe Trichocereeae, or subtribe Trichocereinae (Nyffeler 2002, 317, 319; Lendel et al. 2006, unpubl. data in Nyffeler & Eggli 2010), between the two shown by the results from the molecular analysis carried out by Schlumpberger & Renner (2012: 1335 -1349). According to them, to avoid the polyphyly of Echinopsis s.l. as conceived at the time (Anderson 2001, 2005, 2011; Hunt et al., 2006; Nyffeler & Eggli 2010), there were two possible solutions:
I) A new division of Echinopsis s. l. in at least 7 old genera (Acanthocalycium, Chamaecereus, Leucostele, Lobivia, Reicheocactus, Soehrensia and Setiechinopsis). This is the option adopted by Schlumpberger, which led to the 48 new combinations presented by him in CSI (28: 29-31). This was a solution devoid of internal coherence, as it did not naturally resolve the internal relationships of the clades Cleistocactus sens. str. and Oreocereus (Schlumpberger & Renner 2012: 1342; Anceschi & Magli 2013b, 31: 25).
II) The other solution was constituted by the inclusion of 15 genera hitherto never incorporated before in Echinopsis s.l., as indicated by the analysis (Schlumpberger & Renner 2012: 1336, 1341), to make the genus monophyletic in Hennig’s sense. The latter, as we know, is the hypothesis we supported (Anceschi & Magli 2013a, 22-29; 2013b, 31: 24-27). Referring to the aforementioned booklet and to the article in CSI for all the insights related to the matter treated at that time, we now update what is known, with the following notes:
I) Of the 15 genera often cited to be assimilated in Echinopsis s.l., for the constitution of a monophyletic macrogenus Echinopsis, actually just 6 of these are monotypic genera (i.e. composed of only one species): Denmoza, Mila, Rauhocereus, Samaipaticereus, Vatricania, Yungasocereus; and according to Hunt (2003, 15: 3) "The monotypic genus is a contradiction in terms. Logically (or at least etymologically) the term genus implies a class or group of things of a lower order (in botany, species etc.), i.e. a collection of things with common attributes. ". Not to mention that 2 of the genera in question (Oroya and Pygmaeocereus), are composed of only two species. It is therefore evident that the aforementioned transfer to Echinopsis involves in reality far fewer natural taxa than those which would seem to be initially implicated.
II) it is striking that of the 17 naturally-occurring intergeneric hybrids reported by Hunt et al. (2006, text: 321) and taken from Hunt (2015, 33: 16) for the family Cactaceae, as many as 11 concern the alleged genera within the tribe Trichocereeae, or subtribe Trichocereinae, i.e. 1) xCleistocana (Cleistocactus x Matucana), 2) xEchinomoza (Echinopsis x Denmoza), 3) xEspocana (Espostoa x Matucana), 4) xEspostingia (Espostoa x Rahuocereus), 5) xEspostocactus (Espostoa x Cleistocactus), 6) xHaagespostoa (Haageocereus x Espostoa), 7) xMaturoya (Matucana x Oroya), 8) xOreocana (Oreocereus x Matucana), 9) xOreonopsis (Oreocereus x Echinopsis),10) xWeberbostoa (Weberbauerocereus x Espostoa), 11) xYungastocactus (Yungasocereus x Cleistocactus). We would like to remember, assuming that the term genus still has some meaning in biology and classification, that two genera that are such, that by definition cannot cross with each other, and if not, they are not two distinct genera.
III) Regarding the 'judgment' repeatedly expressed by Hunt (2013, xiii; 2018, 39: 5, 11), "This radical option has been espoused by Anceschi & Magli (2013) but seems unlikely to gain many supporters", related to our taxonomic approach to the solution of the Echinopsis classification problem, a judgment which has already been denied by Molinari-Novoa (2015, 13: 18-21) and by Mayta & Molinari-Novoa (2015, 14: 13-20), we wonder: since when being "radical" would compromise the use of a solution in science, if this is the one that best represents the correct interpretation of the theory in use?
IV) As already stated in our synopsis of the genus Parodia Spegazzini s.l. (Anceschi & Magli 2018, 36: 75), recent molecular analysis (Barcenas et al. 2011, 27: 470-489), have clearly highlighted that most of the genera of the Cactaceae as currently understood are not monophyletic in Hennig's sense (i.e. not sufficiently extended and not supported by a sufficient number of synapomorphies (see Anceschi & Magli 2018, 36: 74-75), or as in the authors’ words “... our least inclusive groupings are significantly larger than currently accepted genera ... However, although many genera are not monophyletic, many of these follow a pattern of a monophyletic core, with one or two outliers suggesting relatively robust groups with 'fuzzy edges' so that in several cases small adjustments to classifications (i.e. moving outside of the genus) may produce monophyletic groups without significant nomenclatural changes. " (ibidem, 488). Regarding this way of operating, we think that the science of classification has reached a crossroads:
a) correctly apply the available theories to the evidence that science shows us through the techniques and tools currently in use (in this case the principle of monophyly in Hennig's sense (1966), having regard to the opposition that is made of the mentioned principle with the concepts of polyphyly and paraphyly, being the second a new concept proposed by this author (see Anceschi & Magli 2018, 36: 74-75).
b) continue to use the paradigms of collecting to distinguish taxa or, if preferred, with the contemporary tools at hand, the use of the 'cynical' species concept, which is, summarized in Kitcher's words as follows: "Species [and genera] are those groups of organisms which are recognized as species [or genera] by competent taxonomists. Competent taxonomists, of course, are those who can recognize the true species [or genera]. " (1984 (51) 2: 308). We think that Hunt's solution (2013, xiii), to solve the problem in Echinopsis, to dust off, in his words, the "old favorites" (and now paraphyletics) Echinopsis, Lobivia and Trichocereus, together with the above mentioned genera of Schlumpberger, in addition to adding confusion to confusion, fall under the second hypothesis. (Quoted fromAnceschi & Magli 2021, 47-49)
