Systematics of the subfamily Thymelaeoideae (Thymelaeaceae) in Southern Africa

Abstract: The subfamily Thymelaeoideae is the larger of two subfamilies in the plant family Thymelaeaceae, consisting of about 820 species in 36 genera. Its members are distributed mainly across Africa, Australia, and Asia. All the southern African members of Thymelaeaceae belong to the subfamily Thymelaeaoideae and comprise about 210 species distributed across eight genera – Dais Royen ex L., Gnidia L., Lachnaea L., Lasiosiphon Fresen., Passerina L., Peddiea Harv., Struthiola L., and Synaptolepis Oliv. Preliminary phylogenetic analyses using plastid (rbcL and trnL-F) and nuclear (ITS) regions revealed that Gnidia was polyphyletic in relation to the southern African genera – Lachnaea, Lasiosiphon, Passerina, and Struthiola and other southern hemisphere genera such as Drapetes Banks ex. Lam., Kelleria Endl., and Pimelea Banks ex. Gaertn. Significant circumscriptions are required to render Gnidia monophyletic. Clarifying the circumscription of Gnidia is also pertinent to making taxonomic changes in the subfamily. This study aimed to resolve the polyphyly of Gnidia using molecular and morphological data. A more robust phylogeny was reconstructed for the subfamily Thymelaeoideae with increased sampling in Gnidia and the addition of two plastid genes (matK and rps16). Morphological characters were reconstructed onto the phylogenies to understand their patterns of evolution within the subfamily...Ph.D. (Botany