Phylogenetic relationships in the Mediterranean Helichrysum (Asteraceae, Gnaphalieae) based on nuclear rDNA ITS sequence data

Abstract

The internal transcribed spacers ITS1 and ITS2 of the nuclear rDNA were sequenced for 41 Helichrysum species (Gnaphalieae), focusing on the Mediterranean group of species, together with eight representatives of other genera of the Gnaphalieae, in order to check the hypothesised monophyly of the Mediterranean Helichrysum group and the correspondence of the sequence data with its traditional sectional classification. The cladistic analysis of sequence data supports monophyly of the Mediterranean Helichrysum excluding H. frigidum and H. montelinasanum. The traditional classification of the Mediterranean species into two sections, Helichrysum and Virginea, is not supported, whereas a group constituted by species from the west Mediterranean area is shown as a moderately supported monophyletic clade in the strict consensus tree. Other results also show and confirm the complexity, still not satisfactorily resolved, of the Helichrysum generic delimitation: Pseudognaphalium luteoalbum appears merged in Helichrysum whereas Helichrysum dasyanthum appears more related to Anaxeton laeve than to any Helichrysum species.