Systematic studies in African Indigofereae (Leguminosae, Papilionoideae)

Abstract

A cladistic analysis of 51 generic and infrageneric taxa in the tribe Indiqofereae (Papilionoideae) is presented, comprising q 570 species in Africa and Madagascar. Traditionally, 4 genera have been recognized: Phylloxylon (q 5 species), Rhynchotropis (2 species), Cyamopsis (q 4 species) and Indigofera (510-520 species in Africa). 3 genera have been reinstated, i.e. Vaughania (11 species), Indigastrum (11 species) and Microcharis (q 26 species). Vaughania was previously considered to be a monotypic genus (later placed in synonomy under Indigofera); the others have recently been treated as subgenera of Indigofera. A new subgenus is described in Indigostrum. (subgenus Argyraeae Schrire) as well as 17 new sections and one subsection in Indigofera. 18 infrageneric taxa in Indigofera are specified at a new rank. Taxonomic affinities with neighbouring tribes are discussed. A historical review is given of infrageneric subdivision. in Indigofera along with a newly proposed classification of infrageneric taxa in Africa. The cladogram is used to study character evolution in the tribe; from a) an ecological perspective (by identifying aptations) and b) a phylogenetic perspective (by identifying constraining interactions between morphologies). Aptations and critical morphologies are mapped on the cladogram to interpret developmental constraints, and the order and direction of character transformations. Key morphologies are a class of developmental constraints defined here for the first time. The cladogram and character analyses are used to interpret a phylogenetic tree of the tribe in Africa. Major phase. in the evolution of Indigofereae are hypothesized on the basis of developmental constraints, phytogeography and ecology. A taxonomic revision above the species level in Africa is presented, including keys and descriptions of genera and infrageneric taxa in Indigofera. Species of Indigofereae occurring in tropical Africa are listed, while a synopsis is given of southern African species with literature citations, synonymy and typification. 29 new combinations are made in Microcharis and Indigastrum.