Senecio pterophorus is an heterotypic synonym of S. grisebachii: Nomenclatural study of the names, morphological notes, and chorology

Senecio icoglossus var. araneosus by Grisebach (now S. grisebachii) and S. pterophorus have been traditionally recognized as distinct species, although some authors highlighed their morphological affinities and argued a study of the original material to clarify their identities. In this paper, the two names are investigated, the first one (S. icoglossus var. araneosus) is typified on a specimen preserved at GOET (neotype), while the holotype (preserved at P) was found for S. pterophorus. For the nomenclatural purposes, the names S. balansae (holotype and isotype, respectively, at K and G), S. icoglossus var. araneosus by Candolle (lectotype in P, designated in this paper), Senecio pterophorus var. apterus and var. verus (nom. superfl. et nom illeg., Art. 52.2 of the ICN) and S. pulcher (lectotype and isolectotype at K, designated in this paper) are also discussed. Morphological observations on material from Australia, Europe, South America and South Africa were done. The results show that S. icoglossus var. araneosus by Grisebach and Candolle are to be applied to different taxa. The Candolle's name is an heterotypic synonym of S. pulcher (an endemic South american species). The Grisebach's name is indeed an heterotypic synonym (syn. nov.) of S. pterophorus, the name S. pterophorus having nomenclatural priority. The characters of five out of the seven varieties described for S. grisebachii have a continuous variability, so their names are to be considered synonyms of S. pterophorus. The origin of the species is discussed, and two hypotheses are proposed: a “natural origin” (disjuction distribution related to a long-distance dispersal event) and a “recent indtroduction” (alien populations and endemic taxon). Morphological and chorological notes are also provided