Overlap of eastern and western mangroves in the South-western Pacific: hybridization of all three Rhizophora (Rhizophoraceae) combinations in New Caledonia

A recent survey of mangroves in New Caledonia located 7 taxa of the genus Rhizophora – with 6 coexisting in one estuary. This is arguably the greatest concentration of co-occurring Rhizophora taxa anywhere. Two are well-known mangrove species of the Indo West Pacific, R. stylosa and R. apiculata, and another, R. samoensis resembles the widespread Atlantic East Pacific species, R. mangle. The other four are hybrid intermediates, R. × lamarckii (= R. stylosa × R. apiculata), R. × selala (= R. stylosa × R. samoensis), and two previously undescribed combinations, R. × tomlinsonii (R. apiculata × R. samoensis) and R. samoensis var. neocaledonica (= R. samoensis × R. × selala). The new entities are unknown elsewhere. While R. × tomlinsonii is considered endemic to New Caledonia, R. samoensis var. neocaledonica may occur elsewhere based on the co-distribution of putative parental taxa. All seven Rhizophora are described with new observations on their morphology and ecology, distribution maps, plus a revised key for the region.