Unraveling relationships in the morphologically diverse and taxonomically challenging "justicioid" lineage (Acanthaceae: Justicieae)

作者：Kiel Carrie A^*; Daniel Thomas F; Darbyshire Iain; McDade Lucinda A

来源：Taxon, 2017, 66(3): 645-674.

DOI：10.12705/663.8

• Acanthaceae
• Diclipterinae
• Justicia
• justicioid
• phylogenetics
• systematics

This is the first study in Acanthaceae to provide a robust and well-sampled phylogenetic framework for the "justicioid" lineage (Acanthaceae: Acanthoideae: Justicieae), a clade that includes at least 1000 species that together occupy essentially the entire distributional range of the family as a whole. Species are morphologically diverse and occupy a wide variety of habitats. Although much progress has been made in understanding phylogenetic relationships within Acanthaceae, well-sampled phylogenetic studies are lacking for justicioids. DNA sequence data from six regions for 178 accessions from across the entire lineage were used to test monophyly and validity of 17 putative genera of justicioids on a global scale. Included among these genera is the species-rich genus Justicia for which we evaluate the current morphology-based classification with a focus on Old World taxa. Our results strongly support monophyly of New World justicioids, including all New World species of Justicia plus species assigned to at least five other smaller genera. Further, with a greatly expanded taxon sample, we confirm our earlier unexpected result that Diclipterinae are embedded within justicioids. As traditionally circumscribed, Diclipterinae lack the morphological traits that mark justicioids and thus had not previously been associated with that group. This study further extends this unexpected result by placing a number of Old World justicioids in a clade that is sister to Diclipterinae. Although some genera of justicioids, notably of Diclipterinae, are monophyletic, Justicia is grossly polyphyletic. We explore these results by examining the diagnostic utility of morphological characters for major clades with a focus on inflorescences, androecia, pollen and seeds. We further use our results as context for documenting evolutionary patterns of floral traits and pollinator relationships, as well as biogeographic patterns, across this species-rich and diverse clade.

• 出版日期2017-6-23