Synonyms

Notocactus oxycostatus*, Peronocactus oxycostatus, Notocactus acutus
* Basionym

Distribution

Brazil (Rio Grande do Sul)

Conservation status

(4)   Endangered, EN B2ab(ii,iii)+2ab(ii,iii);C2a(i)

Comments

The characters that distinguish Parodia oxycostata (Buining & Brederoo) Hofacker, from all other members of the group of Parodia ottonis (Lehemann) N. P. Taylor, in the description of Notocactus oxycostatus Buining & Brederoo (1972, 50-51), are a low number of ribs (6-7) with acute angles; i.e. very sharp, wide at the base (35-40 mm) and deep (20-22 mm). Without these precise characteristics, simple to identify, P. oxycostata cannot be recognized. On the contrary, as described in the last literature (Hunt 1999a, 251; Anderson 2001, 550; 2005; 2011; Hunt et al. 2006, text: 222, 310; atlas: 314, tabs. 314.1, 314.2, 314.3), P. oxycostata appears to be a taxon with nebulous boundaries and is poorly understood. The boundaries that should divide some populations of the taxon conceived are easily labile (the ssp. gracilis), from the variable and dominant P. ottonis. The most tangible example of this confusion is the images that illustrate the taxon in the New Cactus Lexicon (Hunt et al. 2006, atlas: 314, tabs. 314.1, 314.2, 314.3). If we compare the two photos illustrating P. ottonis (ibid.: 313, tabs. 313.3, 313.4), with Fig. 314.3 Parodia oxycostata ssp. gracilis, we note that these three plants, in habitat, could be part of the same natural population (see A&M 764, photo 63). All carry at least 11 ribs, and none of them show the sharp and deep rib of P. oxycostata. Also Fig. 314.1 Parodia oxycostata ssp. oxycostata (P. nothominuscula), is nothing more than one of the possible variants forms of P. ottonis, so much so that the ribs show exact opposite characteristics from what is required by the description of P. oxycostata. The taxon is finally illustrated in fig 314.2, Parodia oxycostata ssp. oxycostata: a specimen with few ribs (8), sharp and deep. The confusion arose from the idea of expanding the concept of one species, which is infrequently encountered in habitat, and whose populations (or groups) are composed of a small number of individuals, spreading over a relatively large portion of territory. This expanded concept now includes in P. oxycostata, groups of taxa with quite heterogeneous characters, the most part published by Ritter in Kakteen in Südamerika (1979, 1). They are: Notocactus glaucinus Ritter, Notocactus glaucinus var. gracilis Ritter, Notocactus glaucinus var. depressus Ritter (ibid.: 168-169, 309, figs. 107, 108, 310, fig. 109), Notocactus securituberculatus Ritter, Notocactus securituberculatus var. miniatispinus Ritter (ibid.: 169, 310, figs. 110, 111), Notocactus acutus Ritter (ibid.: 169-170, 355, fig. 235), this taxon has been added as a synonym of P. oxycostata only in Hunt et al. (2006, text: 310), but previously considered a synonym ofP. ottonis ((Hunt 1999a, 97, 251; Anderson 2001, 549, 744; 2005; 2011), Notocactus harmonianus Ritter (Ritter 1979, 1: 176-177, 318, fig. 118) and finally Notocactus campestrensis Ritter (ibid.: 177, 312, fig. 119). The taxa in question, as just pointed out, are mutual bearers of rather heterogeneous characters. Ranging in fact from N. glaucinus with 9-12 ribs, straight, in triangular section, 1-2 cm high, up to N. harmonianus with 15 ribs, obtuse, 5-7 mm high. Probably this confused idea on the definition of the taxon was born with Hofacker’s publication (1998, 6: 12) of one of the Ritter’s taxa (N. glaucinus var. gracilis), as a subspecies of P. oxycostata, with the name Parodia oxycostata ssp. gracilis (F. Ritter) Hofacker. Now if N. glaucinus has little to do with P. oxycostata, except the height of the ribs, its var. gracilis has even less. Ritter tells us only that the overall body is smaller, and that the ribs are lower and less deeply dentate (Ritter 1979, 1: 168-169), therefore even further from the characteristics of P. oxycostata. All the taxa mentioned show less sharp ribs, and in greater numbers than in the description of N. oxycostatus, or rather, all except one. The only taxon that seems to be seriously morphologically related to P. oxycostata is N. acutus, curiously the only one which initially, and for some still today, is considered a synonym of P. ottonis. The description of N. acutus, seems to be a natural extension of the description, maybe too restrictive, of N. oxycostatus. The ribs are in fact acute at the apex and sharp, as shown in the photo of the taxon in Ritter 19791979, 1: 355, fig. 235), and the number of ribs goes from 6-7, 3,5-4 cm wide (in P. oxycostata), to 7-9, 3 cm wide (in N. acutus). We believe that the concept of P. oxycostata (for having a distinctive meaning, within the P. ottonis populations, and at the same time being close to the description of N. oxycostatus) could at most include N. acutus, the only taxon that seems to be really conspecific. This is a concept already highlighted by Mace (1975, 55), and by Gerloff et al. (1995, 64), even if the latter also included in N. oxycostatus the forms of N. securituberculatus. We believe that all the other taxa assigned by the recent literature to P. oxycostata, should be attributed to the dominant and variable P. ottonis, which can have 6-15 or more ribs, indifferently rounded or acute. (June 2013)

Genus

Parodia

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