Remarkable genetic and specific diversification in <i>Boeckella</i> (Copepoda: Calanoida) from New Caledonia suggests strong micro-endemism

Abstract The relative isolation of islands makes insular biodiversity both fascinating and particularly sensitive to perturbations. New Caledonia is a tropical archipelago hosting high endemism levels and knows many threats (e.g. mining activities). Several areas of the archipelago contain numerous freshwater ponds that functions as insular systems and hosts abundant planktonic crustaceans such as the copepod genus Boeckella. In New Caledonian populations of Boeckella, high genetic diversity with geographic structuration is found, highlighting a potentially low dispersion capacity. All Boeckella populations in New Caledonia are identified on soils with high heavy metal concentrations. These environments are threatened by the mining activities operating since 1873. Additionally, new potential Boeckella species are discussed, tripling the specific diversity of the genus previously known in the archipelago. The narrow distributions of these species of Boeckella might be associated to a commonly observed phenomenon in New Caledonia: micro-endemism. Most insular theories on highly isolated systems are corroborated by these observations. Finally, a phylogenetic analysis of Boeckella using two genetic markers tends to confirm that the species from the archipelago might form a single clade that is a sister group to all other Boeckella species worldwide. These findings change the evolutionary history known of the genus.