Bibliotheca Diatomologica, Volume 38: Insel der Endemiten: Geobotanisches Phänomen Neukaledonien [Island of Endemics: New Caledonia – A Geobotanical Phenomenon]

New Caledonia, a comparatively small archipelago, located in the Southwest Pacific, is remarkable in many respects. The geological conditions, the age and the long geographical isolation are possible reasons for the botanical and zoological particularities of this island. The flora of vascular plants is distinguished by a high percentage of endemic taxa. Diatom taxa are to a large extent cosmopolitan. This is particularly obvious with regard to the marine species although freshwater species are also relevant. Other taxa are characteristic elements of large climatic regions. They grow in both hemispheres in tropical, sub-tropical or in moderate climatic conditions, as well in the Arctic and Antarctic. The zonal groups of the Palaeotropis are also well represented here in limnic and marine habitats, whereas only one new species, but no endemics could be found in the restricted marine littoral area under investigation. Up to now comparatively few taxa are supposed to be endemics of distinct continental areas or of islands. This is confirmed by investigations on many larger and smaller islands and in particular parts of the Australian continent. A comparison with other islands in the Pacific area shows that only 1.5% of the known diatom flora in Papua New Guinea seem to be endemic, 2.3% in the North Island of New Zealand, 2.1% of Eastern Australia, 0.66% of Hawaii, none in Viti Levu, the main island of the Fidjis – neither in brackish nor in freshwater.

New Caledonia, however, offers an exceptional phenomenon of diversity, a "hot spot" of peculiar diatom species development probably due to adaptive radiation. Currently, the author's recent investigations combined with earlier observations lead to the conclusion, that approximately 40% of the total of 643 taxa are new for science and could not be found elsewhere. These condensed considerations point out the remarkable position of the New Caledonian diatom-flora. It may be characterised as a "Galapagos of diatoms". Adlafia, Astartiella and Coxia are described here as new genera and a Latin diagnosis is provided for the genus Eolimna.