Three new diatoms Pinnularia from acid waters in Japan

Abstract

We investigated the taxonomic classif i c ations of three of diatoms growing in inorganic, strongly acidic waters in Japan, and obtained the following results. The undulation of both margins of Pinnularia braunii var. undulata is observed in large individuals only, whereas in small individuals both margins are often swollen and resembles Pinnularia braunii in shape, though the valve breadth of P. braunii is narrower and consequently the status of P. braunii var. undulata should be changed.
The next taxon we investigated is often found growing together with P. braunii. The valve shape closely resembles that of P. braunii, but the valve breadth of this taxon is 4.5-6 mm, against 7.3-8.5 for P. braunii. Since the breadth is clearly smaller, it would seem appropriate to treat this as a new taxon, P. gracilivalvis.
We try to compare the photos of the lectotypes taxon, P. acoricola with specimens with equal valve length which is treated as P. acoricola by many Japanese researcher. the breadth is smaller in all Japanese specimens. Moreover, the valve shape of most of them is elliptical, whereas that in most P. acoricola is lanceolate. For these reasons, we suggest the diatom considered to be P. acoricola in Japan is accepted as a new taxon, P. osoresanensis.