A phylogenetic study of subgenus Polypompholyx: a parallel radiation of Utricularia (Lentibulariaceae) throughout Australasia

Abstract

Phylogenetic relationships among 26 of the 37 recognised taxa of Utricularia subgenus Polypompholyx sensu Müller & Borsch were assessed by cladistic analysis of DNA sequences from the plastid rps16 intron. We also examined the placement of the recently described U. simmonsii (sect. Minutae), which was reported to share some morphological characters with subgenus Polypompholyx. We found strong jackknife support for a monophyletic subgenus Polypompholyx lineage; however, our strict consensus tree shows an unresolved relationship between the sections Polypompholyx and Pleiochasia. Within the section Pleiochasia, we found two supported clades, generally differing in a more northern or southern distribution. Despite high levels of morphological heterogeneity and convergence, we found some clade-specific character homogeneity within these two clades, particularly that of growth and bladder-trap form, and floral structure. Bladder-trap form corresponds most strongly with terrestrial v. aquatic habits. The evolution of filiform corolla appendages corresponds with floral colour, and is possibly associated with sexual mimicry, with those of the upper corolla arising twice independently. Furthermore, we found that U. monanthos and U. novae-zelandiae remain synonyms of U. dichotoma, and that U. simmonsii is not included in the subgenus Polypompholyx, but instead is allied with sections Stomoisia and Enskide of subgenus Bivalvaria.