Phylogenetic relationships in Nartheciaceae (Dioscoreales), with focus on pollen and orbicule morphology

Amolecular phylogenetic analysis of Nartheciaceae is presented, with nine species of the family’s five genera. The main phylogenetic findings are: (a) Nietneria and Narthecium are placed in a clade sister to Lophiola; (b) sister to the Lophiola-Narthecium- Nietneria clade is a clade formed by Aletris and the monospecific Metanarthecium; (c) the inclusion of Metanarthecium luteo-viride in Aletris, as proposed by several authors, is well supported. The pollen and orbicule morphology of representatives of five genera is described. The results underline a close relationship between Nietneria, Narthecium, and Lophiola and confirm the previously reported observations of Metanarthecium pollen and the types of sexine ornamentation in Aletris. Pollen grains of Nietneria are monosulcate with a microreticulate sexine, confirming a close relationship with Lophiola and Narthecium. Spherical smoothsurfaced orbicules were observed in all genera of Nartheciaceae and the presence of a circular perforation on the orbicule surface is potentially synapomorphic for the family.