Abstract
A taxonomic study of the type section of the genus Lebeckia Thunb. (sect.
Lebeckia; syn. Eu-Lebeckia Benth., Phyllodiastrum Walp.) is presented. The
genus Lebeckia (Fabaceae, Crotalarieae) is endemic to the western parts of
southern Africa and the type section is endemic to the Cape Floristic Region.
Species delimitations and relationships within the sections of the genus are not
clear and are in urgent need of a revision since the genus has not been studied
in its entirety for nearly 150 years.
Lebeckia section Lebeckia, now consists of 14 species, all with acicular
(needle-shaped) leaves. Based on fruit morphology, four informal species groups
have here been distinguished within the section. An analysis of morphological
characters revealed the existence of four undescribed species, namely “L.
brevicarpa” M.M.le Roux and B-E.van Wyk sp. nov. ined., [previously confused
with L. sepiaria (L.) Thunb.], “L. brevipes” M.M.le Roux and B-E.van Wyk sp. nov.
ined., (hitherto confused with L. longipes Bolus and L. pauciflora Eckl. and
Zeyh.), “L. uniflora” B-E.van Wyk and M.M.le Roux [previously confused with L.
wrightii Bolus] and “L. zeyheri” M.M.le Roux and B-E.van Wyk [previously
considered to be a variety of L. plukenetiana E.Mey.]
A key to the 14 species of section Lebeckia is presented. Diagnostic characters,
nomenclature, typification and distribution maps of all the species are presented,
discussed and illustrated. Morphological data was used in a cladistic analysis
and resulted in a partially resolved cladogram, confirming the presence of four
(presumably monophyletic) groups within the section. In a molecular systematic
study, four DNA sequences were used to explore relationships, but the resolution
was low and unsatisfactory and the result only partially supported the hypothesis
based on morphological characters. However, the molecular phylogeny agreed
with the morphological analysis in providing convincing support for the
monophyly of the section.
Prof. B.E. van Wyk