Phylogeny and historical biogeography of the Panama-hat family (Cyclanthaceae, Pandanales)

The monocot family Cyclanthaceae (Pandanales)comprises ca. 230 known species in 12 genera restricted to the Neotropics. The family has not been the subject of a species-level molecular phylogenetic study to date, with multiple evolutionary and biogeographic questions about Cyclanthaceae still unanswered. In this study, we address genus- and species-level relationships and the historical biogeography of Cyclanthaceae based on a broadly sampled molecular phylogeny. Two low-copy nuclear genes (phyC, rpb2)and five plastid regions (atpB-rbcL, psbA-trnH, trnL-trnF, trnQ-rps16, matK)representing 99 species and all genera of Cyclanthaceae were sampled, spanning the taxonomic and biogeographic diversity of the family. Our results strongly support the monophyly of all Cyclanthaceae genera and confirm previously proposed hypotheses of intergeneric relationships. Infrageneric relationships are generally well supported, with some exceptions in the genus Asplundia that may require a broader sampling to clarify. The early diversification of Cyclanthaceae is estimated to date back to the Paleocene-Eocene period in South America, where the family possibly arrived through a boreotropical route. The origin of most genera is inferred from the Paleocene of the Tumbes-Chocó-Magdalena region, possibly indicating an earlier origin for this biodiversity hotspot. The current distribution of Cyclanthaceae is likely to have been strongly influenced by major biogeographical events in the Neotropics, such as the uplift of the Andes and the opening of the South America dry diagonal. Further studies that include a broader sample of the large Asplundia-Dicranopygium clade and Sphaeradenia group are required.