(3139) Proposal to reject the name <i>Stevia adenophora</i> ( <i>Asteraceae</i> )

(3139) Stevia adenophora Lag., Gen. Sp. Pl.: 27. Jun–Dec 1816 [Angiosp.: Comp.], nom. utique rej. prop. Typus: non designatus. During the taxonomic study of Stevia species from Chile (Gutiérrez & al. in Phytotaxa 282: 1–18. 2016) and in the framework of an ongoing revision of the South American representatives of the genus, it became evident that Stevia adenophora Lag. presents a controversial taxonomic and geographical situation. The name was originally published by Lagasca (Gen. Sp. Pl.: 27. 1816) for the “Regnum Chilense”, based on material collected by the Spanish botanist Luis Née during the Malaspina expedition (Novo y Colson, Viaje Político-Científico Corbetas Descubierta y Atrevida: 1–681. 1885). Shortly thereafter, it was considered as part of the Chilean flora (Sprengel, Syst. Veg. 3: 448. 1826; Gay, Fl. Chil. 3: 479. 1847; Philippi, Cat. Pl. Vasc. Chil.: 186. 1881). Historical cartography of the late 18th century shows that the boundary between the Captaincy General of Chile and the Viceroyalty of the Río de la Plata lay in the area of the Sierras Pampeanas (e.g., Delamarche, Amérique ou Indes Occidentales. 1792). Records from the expedition's log further indicate that Née, sometimes in company with Thaddäus Haenke, explored both sides of the Andes, collecting plants not only in Chile but also in Mendoza Province (originally belonging to Chile, and nowadays part of western Argentina) and along the Pampas on the way to Buenos Aires. On this basis, the locality “Regno Chilensi” given by Lagasca in the protologue of S. adenophora may actually correspond to present-day Argentina or Chile, and possibly even the northwestern region of Argentina due to its geographical proximity. At the beginning of the 20th century, the first comprehensive study of the Chilean flora already regarded Stevia adenophora as problematic with respect to its geographical distribution (Reiche, Fl. Chile 3: 261. 1901). It was over 100 years later when it was first treated as a doubtful name (Freire & Ariza Espinar, Fl. Argentina 7(1): 409–435. 2014). More recently, in a morphological and taxonomic study of Chilean Stevia, Gutiérrez & al. (l.c.: 14) concluded that S. adenophora was most probably collected in Argentina. While excluding it from the Chilean flora, these authors refrained from taking any final taxonomic decision on the species or on its actual distribution. No original material of S. adenophora has been located in MA (Leopoldo Medina, pers. comm.), nor in any of the major European and North American herbaria (B, BM, C, DS, F, FI, K, KIEL, LD, LINN, NY, PR, S), nor in the principal Chilean and Argentine collections (BA, BAF, CONC, CTES, LIL, LP, SGO, SI). The name has never been employed in taxonomic treatments and has remained obscure, with very limited herbarium representation. Only three specimens were labelled with this name, Venturi s.n. (BA 4707), Carette s.n. (BA 4710) and Storni 74 (BAF), but do not correspond to the diagnostic features provided in the protologue of S. adenophora. Morphological evidence further suggests that as described by Lagasca (l.c.) Stevia adenophora does not exhibit direct affinities with the taxa currently recognized in Chile, but rather shares its general features with species occurring in central-western and northwestern Argentina. According to the protologue, S. adenophora was described as a perennial herb with short-stalked glandular pubescence; opposite, sessile, broadly ovate leaves, trinerved, with obtuse apices, subdeltoid bases, and coarsely serrate margins; loosely paniculate inflorescences with pedicellate heads; pubescent involucral bracts; purple corollas; and a pappus of three, rarely four, awns. These features are partly represented in several Argentine species of Stevia, but no species from either Argentina or Chile fully matches the entire set of characters. Among them, the structure of the pappus—traditionally the most reliable diagnostic character for species delimitation in Argentina—suggests the closest morphological affinity with S. chamaedrys. To a lesser extent, certain characters such as flower colour and inflorescence structure also suggest affinities with S. minor and S. vaga. Despite being the older name, Stevia adenophora has never been adopted in recent taxonomic treatments, while the younger names S. chamaedrys, S. vaga, and S. minor have been consistently recognized and widely used in both classical and modern floristic works (e.g., Cabrera, Fl. Prov. Jujuy 13(10): 58–89. 1978; Freire & Ariza Espinar, l.c.; Gutiérrez & al., l.c.; Rodríguez-Cravero & al. in Austral. Syst. Bot. 37: SB23023. 2024; Zuloaga & Morrone, Fl. Conosur (online). 1999+, accessed 25 Nov 2025). The persistence of these names in authoritative regional accounts and major databases contrasts with the obscurity of S. adenophora, which has remained unused since its original description. Moreover, no original type material has been located despite extensive searches in herbaria where Lagasca, Neé, or Haenke have worked, rendering the name unassignable to any extant taxon with certainty. Under a strict application of the principle of priority, any attempt to treat S. adenophora as conspecific with one of these Argentine species would require replacing a currently accepted and well-established name, thereby producing a disruptive and disadvantageous change in nomenclature. Two alternative courses of action are available for Stevia adenophora: either to designate a neotype or to propose its formal rejection. Neotypification would require selecting material that only loosely fits the vague protologue, thereby forcing an arbitrary interpretation of a locality description that does not correspond unambiguously to any of the Stevia species now recognized in the Andes of Chile or Argentina. Such a choice would inevitably result in the displacement of a well-established name and the introduction of instability. In contrast, rejection of the name under Art. 56 of the ICN (Turland & al. in Regnum Veg. 162. 2025) directly addresses the problem, avoiding unnecessary typification of an uncertain species, and preserves the nomenclature in current and consistent use. Thus, the name Stevia adenophora is here formally proposed for rejection under Art. 56. Acceptance of this proposal will ensure that these well-established names remain secure in floristic and systematic treatments. Rejection of this proposal would instead open the possibility that S. adenophora, despite its uncertain identity and imprecise provenance, could displace names that have been consistently applied for more than a century. The authors thank Paule Juraj (B), Norbert Holstein (BM), Jens Soelberg (C), Alicia Marticorena (CONC), Carolina Peichotto (CTES), Emily Magnaghi and Isaac Lichter Marck (DS), Matt von Konrat and Kimberly Hansen (F), Anna Donatelli (FI), Nina Davies (K), Dietrich Ober (KIEL), Arne Thell and Ulf Arup (LD), Nora Muruaga (LIL), Isabelle Charmantier and Jacek Wajer (LINN), Liliana Katinas (LP), Leopoldo Medina and Eva García Ibáñez (MA), Emily Sessa (NY), Otakar Šida (PR), Mats Wedin and Annika Bengston (S), Nora Deginani (SI), and Gloria Isabel Rojas Villegas (SGO) for their kind assistance and helpful response regarding herbarium specimens. This work was supported by Agencia Nacional de Promoción Científica y Tecnológica, Consejo Nacional de Investigaciones Científicas y Técnicas, and Universidad Nacional de La Plata (Argentina).