Phylogenetic Relationships Within Tribe Hibisceae (Malvaceae) Reveal Complex Patterns of Polyphyly in Hibiscus and Pavonia

Abstract

Abstract— The diverse and spectacular Hibisceae tribe comprises over 750 species. No studies, however, have broadly sampled across the dozens of genera in the tribe, leading to uncertainty in the relationships among genera. The non-monophyly of the genus Hibiscus is infamous and challenging, whereas the monophyly of most other genera in the tribe has yet to be assessed, including the large genus Pavonia. Here we significantly increase taxon sampling in the most complete phylogenetic study of the tribe to date. We assess monophyly of most currently recognized genera in the tribe and include three and thirteen newly sampled sections of Hibiscus and Pavonia, respectively. We also include five rarely sampled genera and 137 species previously unsampled. Our phylogenetic trees demonstrate that Hibiscus, as traditionally defined, encompasses at least 20 additional genera. The status of Pavonia emerges as comparable in complexity to Hibiscus. We offer clarity in the phylogenetic placement of several taxa of uncertain affinity (e.g. Helicteropsis, Hibiscadelphus, Jumelleanthus, and Wercklea). We also identify two new clades and elevate them to the generic rank with the recognition of two new monospecific genera: 1) Blanchardia M.M.Hanes & R.L.Barrett is a surprising Caribbean lineage that is sister to the entire tribe, and 2) Astrohibiscus McLay & R.L.Barrett represents former members of Hibiscus caesius s.l. Cravenia McLay & R.L.Barrett is also described as a new genus for the Hibiscus panduriformis clade, which is allied to Abelmoschus. Finally, we introduce a new classification for the tribe and clarify the boundaries of Hibiscus and Pavonia.