Barnadesioideae

T. F. STUESSY; E. URTUBEY; M. GRUNSTAUDL

Asteraceae.

TICA

Lugar: Barcelona; Año: 2008; p. 1 - 38

The South American subfamily Barnadesioideae comprises 91 mostly herbaceous andshrubby species, concentrated in xeric habitats along the Andes. Its nine genera constitutea monophyletic group sister to all other Asteraceae. The subfamily lacks two cpDNAinversions characteristic of the rest of the family. Wide variation in habit,macromorphological, and micromorphological characters emphasizes the long isolatedevolution of the group. Intergeneric relationships within Barnadesioideae have onlyrecently been clarified. DNA sequence analyses reveal a basal dichotomy withinBarnadesioideae between Chuquiraga, Doniophyton and Duseniella in one clade, andArnaldoa, Barnadesia, Fulcaldea, Huarpea, Schlechtendalia and biphyletic Dasyphyllumin the other. The subfamily is estimated to be at least 23 My old. It is hypothesized thatearly members were distributed along the Andean mountains and in Patagonia and havedispersed northward and eastward. Hummingbird-pollination was acquired several times,probably during colonization of cooler mountain habitats northward towards the equator.The base chromosome number of the subfamily appears to be x = 8, and similar countsfrom the related Calyceraceae support this interpretation. Multiple rounds ofpolyploidisation have likely shaped the evolution of the subfamily. Several evolutionaryquestions remain unanswered, above all the phylogenetic status of the isolated monotypicgenus Schlechtendalia.