in cactusinhabitat.org 2013, the A&M 434, A&M 436, A&M 438, A&M 441, A&M 445 and A&M 449, now identified with Gymnocalycium nigriareolatum, were attributed to Gymnocalycium pugionacanthum Backeberg ex H. Till.
May 2021

In the edition of cactusinhabitat.org 2011-2013 and related booklet (Anceschi & Magli 2013a, 98), Gymnocalycium nigriareolatum Backeberg and Gymnocalycium pugionacanthum Backeberg ex H. Till both appeared as accepted taxa. The position was in line with that of other authors (i.e. Hunt et al. 2006, text: 131-132; Charles, G. 2009, 174-175, 190-192; Anderson & Eggli 2011, 321-322, 324; Hunt, D. R. 2013, XXiii; 2016, 65-66, 134). In the comment accompanying the G. pugionacanthum card in cactusinhabitat.org, however, we underlined the close relationship between the two taxa, an opinion already expressed by Charles (2009, 175). This consideration arose from the evidence that various populations we've detected in 2011 in the Belén area, Catamarca, Argentina (A&M 434, A&M 436, A&M 438), and others detected further north in the direction of Hualfin (A&M 441, A&M 445) attributed to G. pugionacanthum, actually showed in many of their components characters difficult to distinguish from those of G. nigriareolatum in the area of the capital San Fernando (A&M 120, A&M 127). Hence the possible understanding of G. nigriareolatum as a dominant species, which expands from the area of San Fernando del Valle de Catamarca, then to the north-west in the Catamarca region, to the south and to the north of the city of Belén, through the Cuesta de Belén, connection point between the cities of Andalgalá and Belén in the precordillera direction. To verify the connection points between the populations of G. nigriareolatum thus conceived, in November 2013 we carried out a series of new surveys in the Belén area, with particular attention to the populations east of the city, specifically between La Puntilla (rocky tip at the east end of the town of Belén), La Cuesta de Belén, La Quebrada del Cura and Andalgalá, corresponding to our A&M 873, A&M 875, A&M 876, A&M 879, A&M 880 and A&M 882a. Basically the surveys showed a progression from the semaphoronts (Hennig 1966, 6-7, 32-33, 63, 65-67), which on average manifest rounded spines, longer and thinner, close to those of the typical G. nigriareolatum, found in the Belén area, just east of the city, and north towards Hualfin, to the semaphoronts that on average show pectinate, strong, rigid radial spines, more or less straight (typical of the concept of G. pugionacanthum), more evident in the Cuesta de Belén area, to then fall on average in the characters of the first type west of the Cuesta. We emphasize 'on average', as intermediate characters between the two types are often detectable within the same population in all the taxon's areas. Aware of  Meregalli & Kulhánek’s article (2015, 6 (3): 11-24), whose purpose was to limit the distribution of the populations referable to the description of G. pugionacanthum, through the choice of an epitype, to the single area of the Cuesta de Belén, for the spination characters, which would distinguish the populations of this specific area compared to those of the neighboring areas, we would like to substantiate the following objections to the two authors:

a) the authors state: “… , no plants closely matching the type form of G. pugionacanthum [i.e. ... along the Cuesta de Belén ...] were seen in more distant locations of the region. " (Ibid., 17). This is not true. If by the authors' own admission, the individual presented in their fig. 28 (ibidem, 21, fig. 28), is conceived by them as being part of the possible range of the type they propose, we would like to stress that specimens with those morphological characters, not only they are found in the vicinity of the city of Belén, compare the individual in fig. 28 with those of our A&M 434 (photo 05) and A&M 436 (photos 22, 24), two surveys previously attributed by us to G. pugionacanthum, now to G. nigriareolatum, but also in the populations of the typical G. nigriareolatum of the Cuesta del Portezuelo, in the city area of San Fernando, compare again fig. 28 with the A&M 127 (photos 7-8, 10). 

b) the authors give a great pains to limit the population of their G. pugionacanthum to the Cuesta de Belén and the hills just east of the Cuesta in the Belén direction, excluding possible morphological continuities with their type, i.e. with “strong, straight, rigid pectinate spines” (ibidem, 15) or as in the redescription with “… ; lateral spines 3-4 (-5) pairs, pectinate, straight or slightly bent or curved, …” (ibidem, 17), both in the east direction that in the north direction, than in the area of the city of Belén (ibidem 22-23). Actually, as also recognized by the authors themselves, intermediate forms of spination exist (ibidem, 19), and they certainly do not stop either before the city of Belén in an easterly direction, nor at the end of the Cuesta de Belén in a western direction. Of the extension of the forms with longer, thinner and more rounded spines (those closest to the typical G. nigriareolatum, we have already expressed ourselves in point a). For semaphoronts with shorter, pectinate, more or less straight and strong spines, more closer to the conception of G. pugionacanthum, certainly dominant on the Cuesta de Belén, we refer to our A&M 438, La Puntilla, (photo 33), and compare this with the following specimen presented by Meregalli & Kulhánek (ibidem, 18, fig. 14), and again A&M 441, La Cienaga de Abajo, (photos 36, 38, 44-45), to be compared respectively with these other specimens presented by the authors (ibidem, 18, figs. 12, 13, and 11). Both surveys are now far away from the Cuesta de Belén, nonetheless, several individuals show pectinate radial spines, more or less straight, strong and rigid. It also seems correct to remind that some of the populations of G. nigriareolatum that live in the San Fernando area also show pectinate radial spines, stronger and more evident than those of the typical form of the same area. We are talking about the densispinum populations of G. nigriareolatum (A&M 120 (2007), A&M 120 (2011), which constitute a further morphological trait d'union between G. nigriareolatum and G. pugionacanthum. Very similar semaphoronts to the densispinum populations are detectable up to north of Belén, compare again A&M 441, La Cienaga de Abajo (photos 44-45), with A&M 120 (2011), Catamarca, Dique El Jumeal (photos 19, 21, 24, 48). 

c) more generally, in order that the science of classification has some meaning (i.e. that approaches something approximately true in nature) and performs some distinctive function, we believe it is fundamental that it is the type that must adapt to the natural populations, not the natural populations to the type. For example, the replacement of the idea of a type as currently conceived, i.e. based on a single individual, with another that considers a set of individuals, would be more representative of the real variety of a natural species.

Based on what has been said, we feel it appropriate to proceed in the direction of the assimilation of the populations of G. pugionacanthum into the dominant G. nigriareolatum. (Quoted from Anceschi & Magli 2021, 69-72)