Dicoma chatanensissp. nov. (Compositae) from Yemen, and notes on the other species of Dicomeae on the Arabian Peninsula and Socotra

Abstract

Three species of Dicoma and one of the newly re‐established segregate genus Macledium (Dicomeae) are recognized on the Arabian Peninsula and Socotra. The (sub)shrubby Dicoma chatanensis N. Kilian sp. nov. with affinities especially to D. aethiopica from southwest Ethiopia, is described from open habitats of the sea‐facing escarpments of Jabal Chatan in east Al‐Mahra, Yemen. Based on additional material, D. schimperi subsp. cinerea is reconsidered to have a disjunct distribution in north Somalia and southeast Yemen, in the latter region replacing subsp. schimperi. Dicoma tomentosa is very rare in the area and known only from southwest Saudi Arabia, north Yemen and, as a rare weed, from Socotra. The common description and illustration (under Dicoma) of the flowers of the Socotran endemic Macledium canum with lobes rolled backwards spirally is confirmed to be erroneous and a lectotype is designated for the basionym. A key to the four species is provided.