Abstract
Fossil diatom assemblages were documented from outcrops of the Tsumori Formation (Middle Pleistocene) distributed along the Kanayama River, Mashiki Town, Kumamoto Prefecture, Kyushu, Japan.102 taxa in 40 genera were identified for fossil freshwater diatoms in three siltstone samples (KUM-102,104,108) from the Formation. The diatom assemblage of three samples showed dominant taxa of araphid pennate diatoms (14 taxa)with a fruquency of 43%, accompanied with centric diatoms (5 taxa) 27%, biraphid pennate diatoms (73 taxa) 18% and monoraphid pennate diatoms (10 taxa) 12%. Taxonomic information is described on seven species: Cyclostephanos kyushuensis H. Tanaka, Cocconeis placentula Ehrenb., Epithemia hyndmanii W. Sm., Gomphonema vibrio Ehrenb. var. subcapitaturn (Mayer) J. H. Lee, Navicula subcostulata Hust. var. rostrata Hust., Rhopalodia novaezelandiae Hust. and Stauroneis phoenicenteron (Nitzsch) Ehrenb. var. hattorii Tsumura. In the sample KUM-108, fossils of Epithemia hyndmanii were found attached to chips of wood.
