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Phylica L. (Rhamnaceae) consists of about 150 species, most of which are found in Cape Province, South Africa. A number of species are found on islands off southern Africa such as St Helena, Tristan da Cunha, New Amsterdam, Mauritius, Reunion and Madagascar. Phylica has two close relatives, Nesiota Hook. f. (a monotypic genus from St Helena) and Noltea Riechb. (a monotypic genus from South Africa). Most of the species on the mainland are ericoid shrubs, whereas some of the island species and the genera Nesiota and Noltea are broad-leaved trees or shrubs that have retained other putatively primitive characteristics. I assessed tribal relationships in Rhamnaceae and relationships of the family itself using DNA sequences from two regions of the plastid genome, rbcL and trnL-F. This revealed that the closest relatives of Rhamnaceae are Dirachmaceae and Barbeyaceae. The plastid trees support the monophyly of the family and provide the basis for a new tribal classification. Three major strongly supported clades are identified, but morphological characters could not be found to underpin a formal taxonomic description of these three clades as subfamilies. A morphological phylogenetic analysis of Rhamnaceae using 18 characters provided less resolution than analysis of molecular characters. Sequences of trnL-F and internal transcribed spacer nuclear ribosomal DNA (ITS) showed that the genera Nesiota and Noltea are sister to Phylica and palaeoendemic within the context of the tribe Phyliceae and the island species of Phylica form an 'island group' embedded within the genus together with the widespread mainland species P. paniculata. |
