芳野層（中部更新統，熊本県）から見出された淡水生中心類珪藻

抄録

Investigation of nine selected samples from a group of sixteen taken from five different outcrops of the Yoshino Formation (Middle Pleistocene), Kumamoto Prefecture, Japan, revealed six taxa in four genera of fossil freshwater centric diatoms with a relative frequency of 81–99%. Each of the nine samples was dominated by a specific centric diatom. The four dominant species were Cyclotella rhomboideo-elliptica var. rounda Y.Z.Qi & J.R.Yang, Cyclostephanos cf. numataensis H.Tanaka & Nagumo, Cyclotella cf. lacunarum Hust. and Discostella stelligera (Cleve & Grunow) Houk & Klee var. stelligera with C. rhomboideo-elliptica Skuja var. rhomboideo-elliptica as the sub-dominant species in one sample. Taxonomic information on these diatoms is reported here, with light and scanning electron microscope photographs shown for the five reported taxa.