BIODIVERSITY AMONG WEST-AFRICAN RHIZOPHORA - FOLIAR WAX CHEMISTRY

Foliage from 21 red mangroves (Rhizophora mangle, R. racemosa and R. x harrisonii) from different ecogeographic conditions in Gabon, West Af rica, was analyzed for epicuticular wax composition using CC, GC and G C-MS. Aliphatic hydrocarbons ranging from C-23 to C-34 and some triter penoids were identified. Alkanes were the major constituents (46.7-99. 9%), with triterpenoids also accounting for up to 53.3% of the wax ext ract. High contents of octacosane (27.2%) and lower amounts of nonacos ane (14.9%) and hentriacontane (9.8%) distinguished R. mangle from the other two species. R. hizophora x harrisonii was exceptionally rich i n nonacosane (45.3%) with moderately high concentrations of hentriacon tane (25.4%), whereas R. racemosa was intermediate between the two for mer species in its content of these three alkanes. Inclusion of the le ss abundant constituents in principal components analysis provided a g ood separation of R. x harrisonii, whereas the two other species showe d some degree of overlap. Although major alkane patterns can be used t o discriminate among the Rhizophora species examined, we do find subst antial intra-specific variation that may be attributable to population genetic variation; this was least for R. x harrisonii. The hybrid sta tus of this latter species could not be confirmed from the biochemical analyses carried out.