A phylogenetic study of some representatives of the genus Pentaschistis

English: The genus Pentaschistis (Nees) Spach consists of 68 species and is endemic to Africa, with 57 species being indigenous to South Africa and 40 species endemic (Gibbs RusseIl et al. 1990). To date, the chromosome number of 30 species have been reported, as well as the sequences of the rpoC2 gene of two species and the ITS region of one species. In this study, seventeen specimens were cytogenetically examined. The polyploid levels ranged from diploid (n = x = 7) to 14-ploid (n = 7x = 49). Two species were examined for the first time, namely: P. capensis (diploid) and P. veneta (tetraploid). New polyploid levels were also observed for P. viscidula (tetraploidy), P. densifolia (octaploidy), P. rupestris (decaploidy & 14-ploidy) and P. tortuosa (octaploidy). Due to the fact that no, or very few, multivalents were observed, we concluded that the species are alloploids or segmental alloploids tending towards alloploidy. The morphological groupings (Linder & Ellis 1990a) could unfortunately neither be supported nor rejected by cytogenetic evidence alone, therefore cytogenetics was used in conjunction with molecular data to determine the phylogeny. The fragment patterns obtained from RAPDs were used to calculate the genetic distances. A high degree of variation was observed within and between the morphological groups. Cladograms were obtained with the computer programs PAUP and Hennig86, and PAUP gave the most parsimonious cladogram. The resolutions of these cladograms were, however, not good, therefore DAFs was performed. Again PAUP and Hennig86 were used and again PAUP proved to give the most parsimonious clado gram. These cladograms gave a clearer indication of the phylogeny of Pentaschistis, but the genetic distances within and between the species again proved to be high. The ITS} region was sequenced and aligned separately with Clustal W and Malign. These cladograms indicated a close alliance between P. eriostoma and P. curvifolia. The three data sets were combined and a cladogram with much better resolution was obtained. The morphological data was included and had a minor influence on the phylogeny. This cladogram also indicated a sister relationship between P. eriostoma and P. curvifolia. Current data suggest that P. eriostoma could well have developed through the hybridisation of P. curvifolia and that both P. eriostoma are correctly grouped with Pentaschistis. The combined analysis also indicate that the morphological groupings of Linder & Ellis (1990a) is somewhat supported by phylogeny.