Image © Marien van Westen
(after material from English Lake District)
Euastrum pinnatum. Notice deep lateral incurvations and relatively broad, highly dilate apices.
Cell dimensions (L x B): 130 x 75 µm
Euastrum pinnatum resembles Euastrum humerosum, particularly its variety affine. From that latter taxon, Eu. pinnatum differs by a bit higher cell length to breadth ratio, deeper lateral incurvations and a broader (relative to its semicell base) apex. Eu.pinnatum is an oligotrophic, acidophilous species. From the Netherlands, only a few records are known dating from the first half of the last century.
Image © Jan Šťastný (after Czech material)
A cell of Euastrum pinnatum in which not only the basal (or lower lateral) lobes but also the upper lateral lobes are incurved.