Molecular systematics of Old World Apioideae (Apiaceae): Relationships among some members of tribe Peucedaneae sensu lato, the placement of several island-endemic species, and resolution within the apioid superclade

Comparative sequencing of the two internal transcribed spacer regions of nuclear ribosomal DNA was carried out to examine evolutionary relationships among representatives of Old World Apiaceae (Umbelliferae) subfamily Apioideae. Emphasis was placed on delimiting groups within the previously designated apioid superclade and clarifying relationships within and among the peucedanoid genera Angelica, Ferula, Heracleum, and Peucedanum. These spacer data, and those obtained from the chloroplast rps16 intron for a subset of the taxa, also enabled hypotheses on the phylogenetic placement of several narrowly distributed endemic species. The monophyly of Drude's tribe Echinophoreae is confirmed and it is sister to the Socotran endemic genera Nirarathamnos and Rughidia; the Balearic Islands endemic genus Naufraga allies with Apium graveolens; tribes Careae and Pyramidoptereae are recognized formally to be the previously designated clades 'Aegopodium' and 'Crithmum'; and tribes Oenantheae and Scandiceae are each expanded to include two species of Apium, previously attributable to Helosciadium, and four species of Ferula, respectively. Within the apioid superclade, five major lineages are recognized that are consistent with an available molecular evidence: tribe Echinophoreae, the clades 'Pimpinella' and 'Heracleum,' and the more narrowly circumscribed clades 'Angelica' and 'Apium.' Angelica and Ferula each comprise at least two lineages; Heracleum is polyphyletic if Heracleum candicans is retained in the genus; and Peucedanum is distributed in three well-separated clades with some species allied with those species of Angelica referred to Xanthogalum.