Senecio tamboensis sp. nov. and lectotypification of Pentacalia urbanii: resolving taxonomic mysteries in Andean Senecioninae (Asteraceae)

We present the study of Senecio tamboensis, a new species endemic to the Tambo River basin in Moquegua, southern Peru. This taxon is closely related to members of S. sect. Corymbosi ser. Simplices. Senecio tamboensis is distinguished from its closest relative, S. yurensis, by its linear-lanceolate leaves with an acute to acuminate apex, decurrent base, entire or rarely pinnatifid margins, and slight pubescence on both adaxial and abaxial surfaces. Its cypselae are more elongated and narrower than in S. yurensis. A comparative table is provided to differentiate similar species from Peru, Bolivia, and Argentina, along with details on the geographic distribution, habitat, and examined material of the new species. A lectotypification and taxonomic comments for an associated South American Senecioninae, Pentacalia urbanii, are also presented.