For more than 100 years, researchers in Japan, primarily at Tohoku University in Sendai, have been actively studying micropaleontology (specifically, foraminifera). This tradition was started by the late Professor Hisakatsu Yabe, but probably blossomed and became known worldwide as a result of the work of the late Professor K. Asano in the 1950s and 1960s. Despite the fact that some species names used in other parts of the world originated with the work done in Japan and many Western workers have visited Tohoku University to examine various species, the collections are poorly known outside of Japan.
Because so much of the research done in Japan was based at Tohoku University, the best collections of holotypes are there. When the senior author first visited Sendai in 1990, it was to examine a narrow range of species that had importance on the east coast of North America. It soon became apparent that there was much more to examine and that the whole community of researchers studying foraminifera should be made aware these collections.
The standard method of photography is the scanning electron microscope (SEM), but that process is partly destructive because the specimens must be metal coated and the method is thus not suitable for type specimens. Since that time the environmental scanning electron microscope (ESEM), which requires no coating, has been developed. But as any researcher who has tried to identify transparent calcareous species from SEM photos knows, the SEM photo and what is observed under a dissecting scope are not comparable. Problems in depth of field limit the usefulness of ordinary light microscopic photography.
However, a commercially available technique using a Scanning Light Microscope (SLM) allows in-focus pictures of small objects such as foraminifera (Gerakaris 1986; Scott and Vilks 1991). This technique is relatively quick and nondestructive and was deemed appropriate to illustrate as many Japanese Neogene type specimens as could be located.
In addition to fully illustrating species, we felt it important to evaluate each species for possible affinities with other species described in the literature. Although our evaluations are subjective, they should make it easier to compare Japanese species with those observed in Europe and North America as well as improve the usage of taxonomy worldwide. Many who have worked between the east and west coasts of North America can sympathize with "local" taxonomic problems. It is also clear that several Japanese species probably occur in the North Atlantic, but a lack of familiarity with the Japanese types has restricted usage of these names.
We are qualified to help with some of these problems because all the authors of this paper have experience in most of the world’s oceans over a full range of environments. Of the authors, Scott has the most familiarity with the North Atlantic material, which is important here because many of the oldest and most "established" species were first defined in the North Atlantic by early European workers; Takayanagi, Hasegawa, and Saito have more experience in the Pacific and especially with the Japanese material. This knowledge was particularly important in assessing the species because in many cases the types (as we will discuss later) are not representative of the range of variability of particular species.
We hope that the re-illustration of the species here will provide benthic foraminiferal reseachers worldwide with access to this important Japanese collection.
In addition to the existing published species, we include three new species, which are described by Takayanagi.