Systematics of Lindenbergia and Campylanthus (Scrophulariaceae)

Abstract: The plant life of north-east Africa and Arabiahas received much interest in recent years, a fact illustrated by the various ongoing flora projects in the region, e.g., the Flora of Ethiopia and Eritrea, Flora of Somalia and Flora of Arabia. Apart from providing complete taxonomic revisions of Lindenbergia and Campylanthus, the present study aims at the clarification of the morphology, phylogeny, biogeography and systematic position of both genera.The genus Lindenbergia has a distribution ranging from north-east Africa to China and the Philippines. Twelve species are recognized, two of which are described as new. The somatic chromosome number 2n = 32 is reported for three species. The position of the genus within the Scrophulariaceae is analyzed, and it is concluded that Lindenbergia belongs in the tribe Gratioleae. A cladistic analysis of the genus indicates that the first vicarious events took place in Asia rather than in Africa or Arabia, since thephylogenetically basal taxa are found in the Himalayas, A key, descriptions and distribution maps for all species are provided, as well as line drawings for the new species.Campylanthus shows a markedly disjunct pattern of distribution, with two species in Macaronesia, twelve species in north-eastern Africa and Arabia, and one species in western Pakistan. Of the fifteen recognized species, one is described as new. The position of the genus within the Scrophulariaceae is discussed, and it is concluded that Campylanthus is best placed in a tribe of its own, near the Digitaleae. Acladistic analysis including all species indicates a basal split between the western and the eastern species in the genus. A key, descriptions and distribution maps for all species are provided, as well as line drawings for the new species and two other species.A cladistic analysis using ndhF sequences of seventeen taxa from Scrophulariaceae, seven taxa from related families and four outgroup taxa was performed in order to get indications on the systematic position of Lindenbergia and Campylanthus within the family. The results concerning Lindenbergia are unclear since no sequences were available of putative close relatives, whereas the position of Campylanthus near the Digitaleae is corroborated.