Multiple origins of dendroid shrubs in the eastern MediterraneanEuphorbia hierosolymitanagroup (Euphorbiaceae) with description of a new species,Euphorbia lemesiana, from Cyprus

The leafy spurges, Euphorbia subgenus Esula, have one of their diversity centres in the Mediterranean, which is considered to be one of the 25 biodiversity hot-spots. The eastern Mediterranean, in particular, is characterized by its high species richness and is therefore considered to be a cradle for lineage diversification. However, the area remains neglected in phylogenetic studies. Using nuclear ribosomal internal transcribed spacer (ITS) and plastid trnT-trnF sequences, we explored the phylogenetic relationships in the predominantly eastern Mediterranean E. hierosolymitana group, which is characterized by a woody habit. The widespread shrublets E. acanthothamnos, E. glabriflora and E. spinosa, which are similar in habit, are not most closely related, the last two forming a sister clade to other taxa. From the E. acanthothamnos alliance, dendroid shrubs evolved at least two, but possibly four, times, giving rise to widespread E. bivonae and E. hierosolymitana, the Cretan endemic E. sultan-hassei and the here newly described and genetically most divergent E. lemesiana, endemic to Cyprus. We provide a taxonomic treatment and morphological comparison with the similar, but not most closely related, E. hierosolymitana. Our study underlines the phytogeographical peculiarity of Cyprus and contributes to our current knowledge on the diversification patterns in the eastern Mediterranean.