Origin and Evolution of Natural Diversity;Proceedings


Overview of Pleistocene Bryozoans in Japan

Dick, Matthew H.;Takashima, Reishi;Komatsu, Toshifumi;Kaneko, Naotomo;Mawatari, Shunsuke F.

Permalink : http://hdl.handle.net/2115/38443
KEYWORDS : Benthic;Biodiversity;Bryozoa;Climate change;Ectoprocta;Fossil;Japan;Paleoclimate;Pleistocene;Polyzoa;Taxonomy


We compiled a list of bryozoan taxa reported between 1935 and 1995 from Pleistocene deposits in Japan. Our list adds many Pleistocene records to the 1980 checklist of Sakagami et al.: although only a handful of additional Pleistocene records of bryozoans have been published since 1980, many deposits previously considered to be of Pliocene age have now been more accurately dated as Pleistocene. These include the Setana, Hamada, Hirose, Daishaka, Shibikawa, Sawane, Haizume, and Omma Formations. Our list contains 358 taxa, including 97 new to science described from Pleistocene Japan. Previous studies have been concentrated in four regions of Japan: 1) Boso Peninsula, central Honshu, Pacific side; 2) SW Hokkaido and N Honshu in the vicinity of Tsugaru Strait; 3) Noto Peninsula and Niigata, central Honshu, Sea of Japan; and 4) Kikai-jima Island in the Nansei Archipelago south of Kyushu. We present the number of total taxa and new taxa reported per region and formation, and compare the similarities among regions. We report newly discovered Pleistocene deposits from two regions: the Setana Fm. near Kuromatsunai, Hokkaido, and the Oe and "Kita Arima" Fms. on the Shimabara Peninsula, Kyushu. Pleistocene bryozoans are relatively well known in Japan, and with increased taxonomic resolution can provide a 'model system' for investigating the effects of climate change on assemblages of sessile benthic marine animals.