In a revised classification of the Afro-Eurasian genus Romulea two subgenera are recognized, based on characteristics of the corm and tunics. Subgenus Romulea is defined by a corm with a sharp crescent-shaped or circular basal ridge and tunics which split into fine teeth or fibrils while subgenus Spatalanthus is distinguished by a corm that is rounded or pointed at the base with the tunics splitting into coarse teeth. Within these subgenera, sections are delimited primarily on the basis of finer details of corm morphology, and informal species groups called "series" are recognized by a combination of leaf anatomical features and cytology. A synoptic treatment of the genus is presented for sub-Saharan Africa, the Arabian Peninsula and Socotra that includes revised keys to the sections and species and new distribution data. A total of 76 species are recognized for sub-Saharan Africa-Arabia, including five new species described here (R. albiflora, R. discifera, R. lilacina, R. maculata and R. rupestris). Two species, R. papyracea and R. vanzyliae, are reduced to synonomy.
Romulea, Iridaceae, morphology, systematics, sub-Saharan Africa, Arabia, Socotra