Hybrid origin of an annual leafy spurge (Euphorbia subgen. Esula) from the Alborz Mountains (Iran) in the Irano-Turanian floristic region
Pahlevani, A., & Frajman, B. (2025). Hybrid origin of an annual leafy spurge (Euphorbia subgen. Esula) from the Alborz Mountains (Iran) in the Irano-Turanian floristic region. Plant Biosystems - An International Journal Dealing with All Aspects of Plant Biology, 1–10.https://doi.org/10.1080/11263504.2024.2446797
Abstract
The Alborz Mountains represent an area of endemism within the Irano-Turanian floristic region. They are particularly rich in the number of species belonging to Euphorbia subgenus Esula (leafy spurges). Here, we present a new annual leafy spurge discovered in the area. Morphologically and ecologically, it resembles annual Euphorbia szovitsii, the sole representative of Euphorbia sect. Szovitsiae, and Euphorbia arvalis from Euphorbia sect. Arvales. Phylogenetic analyses of the nuclear internal transcribed spacer sequences inferred its sister position to Euphorbia sect. Patellares, which includes perennials growing mostly in more mesic habitats; interestingly, the new species shares partly connate raylet-leaves with this section. Conversely, the plastid sequences indicated that it was most closely related to E. szovitsii. This suggests its hybrid origin, possibly including an allopolyploidisation event in its evolutionary history, indicated by an increased relative genome size compared to E. szovitsii. Based on our integrative approach we describe the new Alborz endemic as Euphorbia alborzensis and include it in E. sect. Szovitsiae. We provide a taxonomic treatment and discuss its morphological affinities with close relatives. Our study highlights the Alborz Mountains as an important area of endemism in the Irano-Turanian region and indicates that further in-depth studies are needed in this region.