Abstract
In 1993, a small population of Uca arcuata was found in the Sashiki tidal flat of Nanjo city, Okinawajima Island, facing Nakagusuku Bay. This location was far isolated from the main distributional range of the species, and a genetic study indicated that this Okinawajima population had a low genetic diversity and a different genetic structure from other populations. We report here that small populations of this species have become newly established in artificial tidal flats adjoining the recently reclaimed Shinko district of Uruma city about 20 km away from the Sashiki population. The genetic structure of the new populations, as assessed by comparison of 3,700 bp sequences of the mitochondrial DNA using PCR-RFLP, is the same as that of the Sashiki population. This suggests that the new populations are derived from the Sashiki population through gene flow by larval transport within Nakagusuku Bay.
