Using integrative taxonomy and multispecies coalescent models for phylogeny reconstruction and species delimitation within the Nastanthus-Gamocarpha clade (Calyceraceae)

The Calyceraceae (47 spp.) is a small family of plants that is sister to the Asteraceae ( similar to 25,000 spp.), one of the largest families of angiosperms. Most members of Calyceraceae are endemic to the Andes and Patagonia, representing an excellent model within which to study diversification patterns in these regions. The single phylogenetic study of Calyceraceae conducted to date revealed that the boundaries of most genera and several species of this family require further analyses, especially the Nastanthus-Gamocarpha clade. In this study, we reconstructed the phylogeny of the Nastanthus-Gamocarpha clade using multispecies coalescent models under BPP and StarBeast2 programs, sampling 63 individuals from 13 of the 14 species recognized to date. We then used this phylogenetic framework to delimit species using BFD and the All method implemented in BPP. Species limits suggested through a coalescent approach were then re-evaluated in the light of morphology, geography, and phenology. Coalescent-based methods indicated that most putative lineages could be recognized as distinct species. Morphological, geographical, ecological, and phenological data further supported species delimitation. Necessary taxonomic changes are proposed. Namely, the paraphyletic Nastanthus is synonymized under Gamocarpha, while five species of Boopis are transferred into Gamocarpha. We used an integrative taxonomic approach to recognize 13 species and one subspecies within the newly circumscribed genus Gamocarpha.