Concluding Studies of Crustacean Biogeography in the Pacific

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It is known that the littoral crustacean fauna of Japan has considerablenumber of elements in common with those of Australia and New Zealand, despite the geographical distance between them. This suggests that the faunas may have commonancestors from the Tethyan Seain the geologicpast. The aim of this project is to understand in detail how the crustacean faunas from these regions are related phylogenetically, and also how certain aspects of algal floras are related. As it takes much time to accumulate microfaunal data, this reports is basedon the limited dataobtained so far.1. Ostracoda : Samples were collected from sea grass and algae at 307 localities along the entire coastof Australia and New Zealand. Cluster analyzes of the ostracodeassemblages revealed that the boundaries of biogeographic provinces are primarily dependent upon local climatic conditions.2. Cirripedia : Based on the mtDNA of barnacles living in the intertidal zone, the genetic similarities among8 species from Japan and 4 species from Australia were determined.3. Decapoda (shrimps) : Macura shrimps associated with seagrass were collected from a large number of localities using a plankton net while skin diving toinvestigate the biogeography of the taxon. It becameclear that the species diversity decreaseswith higher latitude.4. Decapoda (crabs) : Ecological characteristics of species of Ocypodidaeliving in mangrove swamps were studied with respect to taxonomy and geographical distribution. Video-observation of behavioral characteristics, including waving pattern, are useful for integrated investigation of speciation processes and species-level phylogeny. The mtDNA of some species is being analyzed.5.Algae : The main interest lies on the infraspecies diversification process of algaeliving in brackish water. Species of Acrocarpia and And Caulocyctis are of special interest, for they are closely related to some endemic species of Japan.