Pliocaenicus omarensis (Kupts.) Stachura-S. & Khur. was found in diatomite from the Koriyama Formation, Kagoshima Prefecture, Japan. It is characterized by a transversely undulate valve face, puncta that are radially to randomly arranged on the valve face, valve face fultoportulae with three satellite pores arranged in a circle, mantle fultoportulae also with three satellite pores located on slightly recessed costae and a ligula-like segment covering the valvocopula opening.
