Missing Links Between Disjunct Populations of Androcymbium (Colchicaceae) in Africa Using Chloroplast DNA Noncoding Sequences

With the objective of clarifying some aspects of the biogeography, phylogeny, and taxonomy of the genus Androcymbium, we sequenced three chloroplastic DNA noncoding regions (trnL intron, trnLtrnF IGS, and trnY-trnD IGS). These data were analyzed with maximum parsimony and the ancestral areas methods following Bremer. Results show that Androcymbium is not monophyletic and that the origin of its distribution and speciation is situated in western South Africa. Later, it dispersed to North Africa, going first to eastern South Africa. Androcymbium austrocapense and A. roseum allow us to phylogenetically connect the species of western with eastern South Africa, and the southern species with the northern, respectively. The formation of an arid track in Africa at the end of the Miocene explains the colonization of Androcymbium in the Mediterranean basin. Androcymbium wyssianum is a key element in understanding colonization of the Canary Islands. The biogeographical pattern of distribution of Androcymbium fits with many other genera with similar disjunct distributions. This indicates the importance of the Miocene arid track in understanding the floristic connections between northern and southern Africa. Because of the close relationships of Bulbocodium, Colchicum, and Merendera, with Androcymbium inferred from the chloroplast data, restructuring the taxonomy and nomenclature of the tribe Colchiceae may be required.