Molecular phylogeny of Koenigia L. (Polygonaceae: Persicarieae): Implications for classification, character evolution and biogeography

- We examine molecular phylogeny of Koenigia using five markers.
- Koenigia sensu lato is paraphyletic with Aconogonon species.
- We propose Koenigia delicatula be elevated to a new genus.
- The tricolpate pollen and quincuncial aestivation likely evolved early in the history of Koenigia and close relatives.
- Himalayan uplift and Quaternary glaciation facilitated the rapid diversification of Koenigia.

To examine the phylogenetic relationships of Koenigia sensu lato (Polygonaceae), 43 samples representing all species of Koenigia and closely related taxa (e.g., Aconogonon, Bistorta, and Persicaria) were sequenced for nuclear ITS and four plastid regions (trnL-F, atpB-rbcL, rbcL, and rpl32-trnL(UAG)). Phylogenetic analyses indicate that Koenigia recognized by Hedberg is paraphyletic and that the basal species K. delicatula should be reassigned to a separate new genus. Based on these findings, we further propose that the genus Koenigia sensu lato be circumscribed to include five species. Ancestral state reconstruction showed that the pollen apertures likely evolved in parallel in the Aconogonon-Koenigia-Bistorta clade and Persicaria clade and that tricolpate pollen is most likely to be the ancestral state. Quincuncial aestivation likely evolved during the early evolution of Koenigia and its close relatives. Our findings suggest that the uplift of the Himalayas has played an important role in promoting species diversification of Koenigia. Koenigia islandica expanded its range during Pleistocene glacial cycles by tracking changes in newly available habitats.