Abstract
In the adjoining seas of Japan, the most common plankton diatom of the genus Asterionella is Asterionella japonica CLEVE. Asterionella kariana GRUNOW, A. bleakeleyi W. SMITH, and A. notata GRUNOW are also found, but always rarely and moreover in a small amount (S. KOKUBO, 1960)1).
In inland waters of Japan are commonly found two species of the genus Asterionella, namely Asterionella formosa HASSALL and A. gracillima (HANTZSCH) HEIBERG. But Asterionella gracillima is now generally recognized as a variety of Asterionella formosa. Besides are known AsterioneIla subtilissima MEISTER and Asterionella inflata HEIBERG.
Asterionella zigzagostellata ELENKIN, which was reported by H. HIROSE (1950)2) as a common plankton diatom of Lake Abashiri, Hokkaido, is none other than Diatoma elongatum (LYNGB.) AG.
