Biogeography of Marine Podocopid Ostracodes in Micronesia

Abstract

Shallow-water podocopid marine Ostracoda from Micronesian lagoons in the Marianas, Caroline, Marshall and Gilbert Islands in the western Pacific were analysed to establish their diversity and zoogeography within Micronesia and the taxonomic affinities with ostracodes from other tropical regions. Sixty-four bottom lagoonal sediment samples from twelve islands and atolls yielded more than seventy species representing over thirtytwo ostracode genera. Q-mode cluster analysis using Jaccard coefficients showed that, with few exceptions, all or most samples from a particular lagoon form distinct subgroups (Jaccard =0.45-0.50). At lower levels, five groups delineate faunal regions within Micronesia: the Gilbert Islands (Onotoa) in the southeast part of the region, the northern Marshall Islands (Enewetak, Rongelap, Bikini), the southeastern Marshall Islands (Kwajalein, Jaluit, Majuro, Arno), the Marianas and Caroline Islands (Guam, Truk, Pohnpei) and