Placoneis exinguav. capitata Cox, E. J. Placoneis Mereschkowsky: The re-evalutation of a diatom genus originally characterized by its chloroplast type. Diatom Res. 2:145-157 (Cox, E. J. 1987).
This taxon has a linear-elliptical valve with rostrate-capitate ends. The irregularly rectangular central area is large and the striae strongly radiate at the center of the valve. The striae are parallel at the ends and are finely lineate. The striae are also irreluglar in lenght at the central area (Patrick and Reimer 1966).
Synonyms
Navicula exigua var. capitata Patr., Farlowia, 2(2):179, pl. 1, fig. 8. 1945 (Patrick and Reimer 1966).
Ecology
This taxon prefers fresh water that is less than 100 p.p.m. hardness (Patrick and Reimer 1966).