Abstract
Aggericorona ponderosa gen. et sp. nov. and Lentiliforma flammifera gen. et sp. nov. are described as new late Miocene diatom taxa from the Morai Formation of western Hokkaido, Japan. A. ponderosa resembles Endictya, possessing a short cylindrical frustule composed of petri dish-shaped valves, which are loculate with extremely fine inner cribrate vela and outer foramina. Rimoportulae are located in a circle at the junction of the valve face and mantle. Lentiliforma flammifera resembles Pseudohyalodiscus, possessing a biconvex lens-shaped frustule with valves penetrated by numerous fine tubular poroid areolae. Small rimoportulae are arranged in a marginal ring as well as being scattered over the whole valve.
