First record of Diplotaxis kohlaanensis (Brassicaceae) for the eastern African flora with taxonomical and phytogeographical remarks

In eastern Africa, this genus is only represented by D. harra (Forssk.) Boiss. in Somalia and Djibouti, while no native species of Diplotaxis have been recorded from Ethiopia.The finding of Diplotaxis kohlaanensis A.G. Mill. & J.A. Nyberg, originally described from northern Yemen, is here reported for the first time in the Simien Mountains.

Our finding has a particular phytogeographical and ecological significance, highlighting the relevant floristic relationships of the Arabian Peninsula mountains with the Ethiopian highlands. In addition, our investigations confirm the outstanding number of exclusive taxa shared by these two areas testifying to the past phytogeographical connection between these two territories. D. kohlaanensis is localised on the high-altitude cliffs, which represent a highly conservative environment for relict species.