The Rhynchosia totta complex (Phaseoleae, Fabaceae) in Southern Africa, including the description of a new variety and new species

Abstract

Background: The Rhynchosia totta complex is one of three taxonomically complicated African groups in the genus Rhynchosia. Numerous southern African species and infraspecific taxa (at least 19 names, 17 species and 2 varieties) have been described by various authors in the past, but were later reduced into synonymy with  R. totta. Currently, only the typical variety is recognised in Southern Africa.
Objectives:  To investigate and update the circumscription of the taxa within the  R. totta complex in southern Africa and to update their synonymies and distribution ranges.
Methods: Specimens of R. totta at GRA, JRAU, K, NH and PRE were studied and compared, and measurements of characters recorded. Populations were also observed during field studies.
Results: The examination of numerous specimens, as well as field investigations, has prompted the recognition of four varieties (one described here as new: R. totta var. longicalyx) and a new species (R. pedunculata) in southern Africa.
Conclusions: A great variation in leaf structure and vestiture occurs within the R. totta complex, with the extreme forms easily recognisable. However, the total number of varieties are limited to four [R. totta vars. totta,  longicalyx,  rigidula and venulosa] and a new species described to accommodate specimens with a distinctly prostrate habit and upwardly directed leaves.