Non-monophyly of Siberian Erythronium (Liliaceae) leads to the recognition of the formerly neglected Erythronium sajanense.

Four Erythronium species have been traditionally recognised within Eurasia based on their disjunct distributions and the slight morphological divergence between them: E. dens-canis, E. caucasicum, E. sibiricum and E. japonicum. The range of E. sibiricum includes adjacent parts of southern Siberia, Kazakhstan, China and Mongolia in the Altai-Sayan mountain region. Despite several recently proposed taxa within the range of E. sibiricum (E. sajanense, E. sibiricum subsp. altaicum, E. sibiricum subsp. sulevii), this species has never been tested for genetic subdivisions. We here used nucleotide sequence variation in one nuclear (internal transcribed spacer) and two plastid (rpl32-trnL, rps15-ycf1) regions to test for genetic divisions within Siberian Erythronium and, in particular, to examine the phylogenetic position of E. sajanense. The plastid phylogeny revealed a basal polytomy among E. japonicum, E. sibiricum populations pertaining to E. sajanense and a third strongly supported lineage that includes E. dens-canis, E. caucasicum and the remainder of E. sibiricum, thus rendering Siberian Erythronium non-monophyletic. The nuclear topology agrees with the plastid one in recovering E. sajanense as a distinct lineage that is weakly supported as sister to E. japonicum. Topological incongruences exist between the plastid and nuclear phylogenies but these do not affect the taxonomic recognition of E. sajanense (endemic to the Western Sayan Mts.). This species is morphologically distinguishable on the basis of its subulate stamen filaments. Whereas nuclear phylogeny failed to resolve any genetic grouping within E. sibiricum s. str., plastid data recovered a deep (possibly phylogeographically meaningful) lineage from samples referred to as E. sibiricum subsp. altaicum.