Species limits in Cannomois virgata complex (Restionaceae)
The variation in the nut morphology, floral and inflorescence morphology, culm morphology and culm anatomy of the Cannomois virgata complex are described. It is shown that this variation is best expressed by recognising three main clusters: the NW-Swartberg, aledonLangeberg and Coastal. The existence of these clusters was largely influenced by the size of the nuts, bracts, perianths and hollow cavity to culm diameter ratio. These traits were congruent with the overall morphometric variation, shown by the results of the phonetic analysis. The clusters correspond to three species proposed under the operational definition, which recognises species from differentiated clusters in phenetic space whose distinctness was assumed to be the manifestation of underlying fixed and qualitative differences following speciation. These units were considered appropriate as terminals for phylogenetic reconstruction. Empirical comparison of six prevailing species concepts was made by taking advantage of a common operational exigency i.e., the use of phenotypically irreducible clusters of individuals as first order estimates of species. Also, diagnostic characters were found in each of the clusters indicating the existence ofa species complex, rather than a single taxon. I therefore propose that the name Cannomois virgata (Rottb.) Steud. be restricted to the individuals of the Coastal group from which the type was collected. A new species, Cannomois grandis Mujaju, is proposed for the plants belonging to the Caledon-Langeberg group, owing to the giant form exhibited by these plants which are 2 to 3.5 metres tall. The name, Cannomois saundersii Mujaju, was proposed for the NW -Swartberg, in recognition of Mr. Saunders, a seed collector. The distribution of the species were related to the cladogram, suggesting that speciation may have been sympatric for all taxa or somewhat allopatric as shown by the NW -Swartberg taxon which has an overall northern inland distribution within the Cape Floral Region in comparison with the other two.
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