Abstract
Studies of micromolluscs are essential in the malacology of the 21st century. Our understanding of molluscs has been chiefl y based on large-sized species, and there are little-known taxa that comprise only of small-sized species. In Japan, an obvious change occurred from classic conchology to more advanced microscopic work in the 1990s, but further research must be accelerated to reveal the entire fauna. In this review, a summary of the current state of knowledge is given for all known micromolluscan families distributed in Japan. Since the 1990s new micromolluscs have been described from various microhabitats such as the undersides of half-buried boulders, burrows of other invertebrates, submarine caves, sunken wood, deep-sea hydrothermal vents and cold seeps. These are promising habitats for more intensive sampling in addition to unexplored environments. Basic taxonomy is still necessary in advancing biological studies at all levels including anatomy, molecular phylogenetics, development, ecology, and paleontology. The importance of micromolluscs is also rising in the fi eld of conservation biology, especially with regard to endangered and introduced species. The genus Lepetella (Lepetellidae) is recorded for the fi rst time from Japan.
