A revision of A frican V elloziaceae based on leaf anatomy characters and rbcL nucleotide sequences

The A frican V elloziaceae is revised mainly using evidence from leaf anatomy and rbcL sequence data. X erophyta is the only A frican genus in the family. Forty‐five species are recognized in A frica, 11 of which are described as new and distinct on the basis of morphological, anatomical and/or genetic characters; one species is known to occur on the A rabian P eninsula, and 25 species are presently identified in M adagascar. The leaf anatomy of all X erophyta spp. and the rbcL sequences of 44 X erophyta spp. are examined. Four distinct types of leaf anatomy are (re‐)defined and, with additional anatomical and morphological features, are used to produce a key to A frican X erophyta . For each species, the morphology, leaf anatomy, synonymy, distribution, extensive literature sources and specimens used are given. The combined anatomical/genetic evidence allowed the description of the new species and the definition of X . simulans as singular in A frican V elloziaceae with leaf anatomical similarities to the S outh A merican V ellozia plicata and to C yclanthaceae. The analysis of the rbcL sequence data supports the C hinese genus A canthochlamys as sister to V elloziaceae s.s. , the monophyly of the O ld W ord genus X erophyta and its separation from the N ew W orld taxa. In X erophyta , a well‐supported clade includes all species with radial isolateral mesophyll ( B arbacenia ‐type leaf anatomy). The other leaf types do not separate into uniform clades. A M adagascan clade houses species with V ellozia ‐ and X erophyta ‐type leaf anatomy and also contains the pan‐ A frican X . humilis . © 2013 The Linnean Society of London