Nonea palmyrensis (Boraginaceae): morphology and phylogenetic affinities of a rare endemic to the Syro-Iraqi desert

Based on collections by the authors from the Syrian desert, the morphology and phylogenetic affinities of the rare species Nonea palmyrensis were investigated. An original description and iconography of the species are given, and a lectotype is designated. Micro-characters were examined by means of scanning electron microscopy (SEM). Clear palynological affinities with the Irano-Turanian species N. longiflora were found. The two taxa share five-aperturate pollen grains and a micro-reticulate ornamentation of the tectum. Phylogenetic relationships were analysed using ITS1 sequences of nuclear DNA obtained from 26 species of Nonea. Bayesian and Parsimony analyses retrieved N. palmyrensis as sister to the Mediterranean N. echioides. Together with the Irano-Turanian species N. melanocarpa, they form a moderately supported clade with unresolved relationships. No clear synapomorphies between the three species could be detected in terms of pollen or nutlet morphology. The possibly adaptive nature of some morphological traits peculiar to N. palmyrensis are discussed.