Budding speciation and neotropical origin of the Azorean endemic liverwort, Leptoscyphus azoricus

The origin of plant species endemism in Macaronesia, one of the 25 world biodiversity hotspots, has traditionally been either interpreted as a result of the dramatic reduction of a broader tertiary distribution range during the Ice Age or neoendemism. This hypothesis is tested here in the context of a species-level phylogeny employing chloroplast trnL-trnF and atpB-rbcL sequences in the leafy liverwort genus Leptoscyphus (Lophocoleaceae). The data suggest that the Azorean endemic Leptoscyphus azoricus originated from parental populations of the Neotropical Leptoscyphus porphyrius by long-distance dispersal across the Atlantic and subsequent isolation. Possible reasons for the differences in the origin of endemism in angiosperms, wherein by far most endemic species have their close relatives on the European and North African continents, are discussed.