South America holds the greatest diversity of native daisies (Asteraceae) in the world: an updated catalogue supporting continental-scale conservation

Abstract

Asteraceae is the world's richest plant family and is found on all continents, in environments ranging from the coast to the highest mountains. The family shows all growth forms and, as in other angiosperm families, species richness is concentrated in tropical regions. South America has the highest diversity of Asteraceae in the world, yet taxonomic and distributional knowledge gaps remain. This study compiles an updated catalog of Asteraceae native to South America, based on national and regional checklists and ongoing large-scale flora projects. The resulting checklist includes a total of 6,940 species and 564 genera native to South America to date, which represent about a quarter of the family's global diversity. Countries already considered to be megadiverse show the greatest diversity, such as Brazil with 2,095 species, followed by Peru (1,588), Argentina (1,377), and Colombia (1,244), with this diversity mainly focused on the Brazilian Highlands and the Andes. Species endemism also peaks in Brazil, but Sørensen distances reveal the Chilean flora to be eminently different from the rest of the continent. Tribes better represented in the continent are Eupatorieae, Senecioneae and Astereae, also with a remarkably presence of entirely South American subfamilies representing earliest diverging lineages of the Asteraceae, such as Barnadesioideae, Wunderlichioideae, Famatinanthoideae, and Stifftioideae. It is estimated that the discovery and description curves have not yet stabilized, and the number of species is likely to increase by 5 to 10% in the coming years, posing major challenges to continental-scale conservation.

Keywords: Andes; Brazilian Plateau; Compositae (Asteraceae); IUCN; diversity; large-scale conservation; megadiverse countries.

Figure 1

Diversity in growth form and floral morphology in representatives of the Asteraceae across South America: (A) Espeletia hartwegiana Sch. Bip. ex Cuatrec., from the Andean Páramos; (B) Espeletia summapacis Cuatrec., from the Colombian Páramos; (C) tree species Archidasyphyllum excelsum (D. Don) Cabrera, from coastal central Chile; (D) Senecio humillimus Sch. Bip. ex Wedd., creeping species from the Central Andes; (E) Senecio formosoides Cuatrec., representative of the most species-rich genus at the continental scale; (F) Stifftia fruticosa (Vell.) D.J.N. Hind & Semir, Brazilian representative of the subfamily Stifftioideae; (G) Wunderlichia insignis Baillon, an endemic species from Brazilian inselbergs and representative of the subfamily Wunderlichioideae; (H) Gypothamnium pinifolium Phil., representative of a monospecific genus from Atacama; (I) Inflorescence in Central Andean Polyachyrus sphaerocephalus D. Don. [photo credits: F.A. Avila, M. Monge, A. Moreira-Muñoz].

Figure 2

Map of South America representing the diversity of the family across the continent. The map was elaborated with the native/endemic species numbers per country from Table 1 , by means of ArcGIS Online (www.arcgis.com). The resulting image was processed in Illustrator 2020 (ver. v24.3.0, Adobe). A daisy symbol was used to depict the proportion of each category and its size was adjusted to reflect species proportions present in each country. The size of the symbols represents the number of species per country. Purple represents the proportion of endemic species in each country.