Phylogenomics and integrative taxonomy reveal two new species of Amana (Liliaceae)

Abstract

Until now the genus Amana (Liliaceae), known as ‘East Asian tulips’, has contained just seven species. In this study, a phylogenomic and integrative taxonomic approach was used to reveal two new species, Amana nanyueensis from Central China and A. tianmuensis from East China. A. nanyueensis resembles Amana edulis in possessing a densely villous-woolly bulb tunic and two opposite bracts, but differs in its leaves and anthers. Amana tianmuensis resembles Amana erythronioides in possessing three verticillate bracts and yellow anthers, but differs in aspects of its leaves and bulbs. These four species are clearly separated from each other in principal components analysis based on morphology. Phylogenomic analyses based on plastid CDS further support the species delimitation of A. nanyueensis and A. tianmuensis and suggests they are closely related to A. edulis. Cytological analysis shows that A. nanyueensis and A. tianmuensis are both diploid (2n = 2x = 24), different from A. edulis, which is either diploid (northern populations) or tetraploid (southern populations, 2n = 4x = 48). The pollen morphology of A. nanyueensis is similar to other Amana species (single-groove germination aperture), but A. tianmuensis is quite different because of the presence of a sulcus membrane, which creates the illusion of double grooves. Ecological niche modelling also revealed a niche differentiation between A. edulis, A. nanyueensis and A. tianmuensis.