Browsing by Author "Bruyns, Peter V"

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    Huernia humpatana (Apocynaceae) a new species from southern Angola
    (2010) Bruyns, Peter V
    A new species, Huernia humpatana Bruyns (Apocynaceae–Ceropegieae), closely related to H. similis N.E.Br., is described from the Chela Mountains of Huila Province in southern Angola. The two species are distinguished by the 5-angled and erect stems with more prominent tubercles up to 6 mm long joined into clear angles and separated by V-shaped grooves in H. humpatana as opposed to very obtusely 4-angled stems with tubercles only 2 mm long and only indistinct grooves between the angles in H. similis. Furthermore, in H. similis the nodding corolla is ± 9 mm in diameter with sepals ± 2 mm long, while in H. humpatana the horizontally facing corolla is 18–20 mm in diameter with sepals 4–6 mm long.
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    Molecular and morphological phylogenetic analyses of Euphorbia L. (Euphorbiaceae) with an emphasis on Southern African representatives
    (2003) Mapaya, Ruvimbo Jessy; Hedderson, Terry A; Bruyns, Peter V
    The genus Euphorbia is morphologically diverse and nearly cosmopolitan. Both succulent and non-succulent species are found within the genus. Succulent species are found in most arid and semi-arid areas of the world, but show their greatest concentration and diversity of form in Southern Africa especially the Cape Floristic Region. The monophyly and phylogenetic relationships of the genus Euphorbia were investigated based on morphology and on sequences of the nuclear ribosomal internal transcribed spacer (ITS) and chloroplast psbA-trnH intergenic spacer. Fifty-one species of Euphorbia and four outgroups from Monadenium and Ciutia were sampled. Matrices were analysed using parsimony and maximum likelihood methods. Separate analyses of data partitions resulted in largely non-conflicting topologies; therefore the data sets were combined. The results showed that the genus Euphorbia is paraphyletic and four monophyletic groups with a number of putative synapomorphies defining each clade were strongly supported in most analyses. The Cape succulents fall into two well-supported clades. The results thus provided evidence for Cape radiations. Most analyses indicated that one of the Cape groups is sister to a group consisting of species mostly from Southern Africa (excludingthe Cape Region). Increased taxon sampling is however needed to clarify relationships within the monophyletic groups. Morphological characters recovered broad groups within Euphorbia. Due to inadequate sampling in some sections, modifications in the present classification of Euphorbia are not suggested. The total evidence tree was used to explore morphological character evolution through character state optimisations. The presence of root tubers was homoplasious and this character state is hypothesized to have arisen at least five times under current sampling. Cylindrical stems, conspicuous leaves and absence of leaf spines were some of the pleisiomorphic states observed in some sampled members of the genus Euphorbia. Although the results obtained in the CUlTent study are preliminary, they have created further challenges for future studies of phylogenetic relationships and morphological character evolution in the genus Euphorbia.
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    A revision of Hoodia and Lavrania (Asclepiadaceae-Stapelieae)
    (1994) Bruyns, Peter V
    Hoodia Sweet ex Decne is revised to contain 13 species which are divided into 2 sections. Sect. Hoodia contains H.currorii, H.dregei, H.gordonii, H.juttae and H.parviflora. Sect. Trichocaulon contains H.alstonii, H.flava, H.mossamedensis, H.officinalis, H.pedicellata, H.pilifera, H.ruschii and H.triebneri, all except H.ruschii formerly constituting the section "Eutrichocaulon", the so-called "spiny" species of Trichocaulon. The remainder of Trichocaulon, the section Cactoidea, is transferred to Lavrania Plowes. This genus then consists of the monotypic section Lavrania (L.haagnerae) and Sect. Cactoidea containing L.cactiformis, L.marlothii, L.perlata and L.picta.