Taxonomic notes on the genus Neorautanenia (Fabaceae–Phaseoleae)

Abstract

Background: Neorautanenia is a small genus in the subtribe Glycininae within the tribe Phaseoleae in the family Fabaceae. It is distributed in southern and Tropical Africa. Historically, the genus is known to consist of three species, namely, N. brachypus, N. ficifolia and N. mitis; morphological data suggest that these should be reduced to two.

Objectives: The aim of this article is to formally sink N. brachypus into the synonymy of N. mitis and to provide the correct typification, diagnostic features, diagnostic key, distribution maps, as well as illustrations of the morphological features of the two species.

Methods: Observations were made on herbarium specimens housed at PRE. Morphological features were studied and measurements of characters recorded.

Results: Neorautanenia mitis is extremely variable morphologically, so that several authors recognised many different variants, some of these as distinct species, including N. brachypus. Examination of numerous specimens, however, indicates that these are merely morphological and/or geographical variants of N. mitis. This observation prompted Verdcourt to place this taxon as a synonym of N. mitis; however, he reversed that decision 30 years later. It has become necessary to revert to the original decision.

Conclusions: Neorautanenia brachypus is formally reduced to a synonymy of N. mitis and as a result the genus comprises only two species.