Molecular and morphological agreement in Pittosporaceae: phylogenetic analysis with nuclear ITS and plastidtrnL–trnF sequence data

Abstract

Pittosporaceae are a small family of flowering plants largely restricted to Australia, and entirely limited to the paleotropics. Two independent molecular datasets have been constructed with a representative sample from all nine genera of Pittosporaceae to test phylogenetic relationships suggested by recent morphological studies and to examine current morphological delimitations of genera. DNA sequence data derived from the ITS region of nuclear rDNA and from the trnL–trnF region of the chloroplast genome agree in uniting all species sampled from Pittosporum within a single clade, together with all species sampled from the previously segregated genus Citriobatus. Molecular data also confirm that members of the recently established genus Auranticarpa must be excluded from Pittosporum, and that another segregate genus, Sollya, should be placed within Billardiera. Hymenosporum remains a distinct, single-taxon lineage and Rhytidosporum is also confirmed as distinct. In most respects, our results are in agreement with recent taxonomic revisions based on morphology, and support an Australian origin of Pittosporaceae. Multiple dispersal events of Pittosporum from Australia to the islands of the Pacific and Indian Oceans, including New Zealand, are suggested, as well as island hopping throughout the Pacific.