Biodiversity and biogeographyof amphidromous fishes from New Caledonia,a comparison with Vanuatu

摘要

Amphidromous fishes have a life cycle adapted to the conditions of insular rivers which are subject to extreme climatic and hydrologicalseasonal variations and have the highest levels of endemism. The presence or absence of these species and the number of endemicsare good indicators for comparing the biodiversity of neighbouring islands and understand their past history. This paper is the firststudy comparing amphidromous Gobiidae and Eleotridae (Teleostei) of New Caledonia and Vanuatu. Thirty-two amphidromousspecies have been caught: 21 Gobiidae, 9 Eleotridae and 2 Rhyacichthyidae. They are all indigenous species. Vanuatu has moreamphidromous species and more endemic species than New Caledonia despite its smaller surface area, smaller river basins andyounger age. But, New Caledonia has one endemic species that is considered as one of the most primitive gobies known to date. InNew Caledonia, the biodiversity of amphidromous species seems to be best explained by the age of this country and the substratetype of the rivers; in Vanuatu, the biodiversity seems to be best explained by the proximity of a supposed biodiversity centre situatedin the Indonesia-Philippines area. The study of the phylogeny of this group of fishes will improve our understanding of the contrasteddistribution of these related species and will help to explain the colonisation of the different islands.