Another cell of Eu. insulare showing chloroplasts with a big, central pyrenoid.

Euastrum insulare. Notice 3-lobed semicells consisting of a basal part and an apical part that are more or less rectangular in outline. The apices are marked by a slight median indentation.

Cell dimensions (L x B): 23 x 17 µm



Desmid of the month
June 2016

Euastrum insulare

Eu. insulare is one of the small-sized Euastrum species that might be considered a species of the genus Cosmarium as well, for the most discriminating feature with respect to Cosmarium, viz., a median apical indentation or incurvation, is only weakly expressed. Semicells of Eu. insulare are 3-lobed. Both the basal and the apical part of the semicell body are more or less rectangular in outline. Cell wall pores are fine and light microscopically often hardly visible*. In the Netherlands, Eu. insulare is rather common in various mesotrophic water bodies.

* SEM pictures may reveal, next to those fine pores, also some deeper pits, partly merging into furrows.

SEM picture of Eu. insulare showing scattered cell wall pores.

SEM picture of a semicell of Eu. insulare showing scattered, fine cell wall pores and a larger, central pit.



SEM picture of Eu. insulare showing several deep cell wall pits (next to the finer pores) partly merging into converging furrows.