In the diatom collections from the Asokai (Yosanaikai) Lagoon, Kyoto Prefecture, I found a specimen which was nearly akin to Navicula johanrossii GIFFEN, but one of the character, striae density did not agree with the original description. Through the kindness of Dr. M. H. GIFFEN (South Africa), I have been enabled to examine the type specimen of Navicula johanrossii. The specimen collected from the Asokai Lagoon was investigated by light and scanning electron microscope. Based on the informations obtained from the microscopical observations, the type specimen and specimen from the Asokai Lagoon, and furthermore the description from another locality, namely Indian River, Florida (NAVARRO 1982) were compared each other. The specimens from three localities have a great deal in common from a micromorphological point of view, but only the striae density is not same. I addition to this, the salinity value of three habitats is different. If the assumption that the striae density of one taxon is variable and is transformed with the change of environmental conditions (STOERMER 1967, LANGE-BERTALOT 1980), is accepted to this taxon, the difference of the striae density in three localities can be regarded as the result of the difference of salinity level of habitats. But the reality of this presumption is somewhat questionable owing to the paucity of information of the distribution. I wish to pay attention to the future report of this taxon.
View full abstract