Taxonomic studies on Japanese nudibranchs (Molluscs).

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Collections of materials were made at various localities in Japan, and close observations of both external and internal (reproductive systems) morphology were done on the specimens. Taxonomic works were achieved especially on the species of suborder Aeolidacea. By careful analysis of morphological variation, some cryptic species were discovered. One of the most interesting aspects revealed by this project is that the cryptic species often occur sympatrically showing some different ecological features. In order to perform further ecological works, identification of the species in pediveliger stage was attempted, and it became possible in several species.In addition to several new species, many species which had not known in Japan were discovered through this project. Distributional features were studied for these species, and it was suggested that human activities such as shipping may affect the dispersion of some species which lack long planktonic phase in their life history.Studies for re-evaluation of the systematics in higher taxa and review of the phylogeny are now carrying out. More careful observations of the internal morphology are necessary before the completion of the work.