A reassessment of tribal affinities of the enigmatic genera Printzia and Isoetopsis (Asteraceae), based on three chloroplast sequences

The tribal affinities of two dubiously placed genera of the Asteraceae, Printzia and Isoetopsis, were assessed by using three chloroplast DNA sequences, the trnL/F spacer, the trnL intron and the matK coding region. The outgroup was represented by two species of the tribe Barnadesieae, whereas one to six genera (43 species including Printzia and Isoetopsis) of the tribes of the Asteroideae [Anthemideae (six genera), Astereae (five) Calenduleae (two), Gnaphalieae (six), Heliantheae s.l. (five), Inuleae s.str. (three), Plucheeae (two), Senecioneae (four)] and Cichorioideae [Arctotideae (one), Cardueae (two), Lactuceae (two), Liabeae (one), Mutisieae (one), Vernonieae (one)] were chosen as the ingroup. Phylogenetic analysis indicates that both Printzia and Isoetopsis have a strong affinity with members of the tribe Astereae. At some point in their taxonomic history, both genera had been placed in this tribe and there are good morphological and chemical characters that justify this placement.