Phylogenetic relationships, based on allozyme data, between six cycad taxa indigenous to South Africa

Phylogenetic relationships between Encephalartos altensteinii Lehmann, E. friderici-guilielmii Lehmann, E. lehmannii Lehmann, E. natalensis Dyer and Verdoorn, E. transvenosus Stapf and Burtt Davy and E. villosus Lemaire were studied, using Cycas revoluta Thunberg as outgroup. Three continuous and one discontinuous buffer systems were used and gene products of 21 enzyme coding loci were examined by horizontal starch gel-electrophoresis. A biochemical key, based on fixed allele differences, is presented. Fixed allele differences at one locus between E. altensteinii and E. natalensis may confirm that these species do not share the same gene pool. However, the genetic distance is the least (0.042) between these two species, compared to the mean genetic distance value of 0.222 for the other ingroup taxa. The results are discussed with reference to affinities based on morphology and distribution.