Cosmarium
Desmidiaceae –
Archaeplastida

Observations on ***Cosmarium venustum* var. *excavatum***

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Cosmarium venustum var. excavatum (B.Eichler & Gutwinski) West & G.S.West 1895

Most likely ID: n.a.

Basionym: Cosmarium trilobulatum var. excavatum Eichler & Gutwinski 1894

Add’l Synonyms: Cosmarium venustum f. ocellatum Ducellier 1918

Sampling date 06/2024. Scale bars indicate 25 µm.

Two images.

The first image shows a cell in frontal view and one below in apical view. The apical view reveals the cell wall thickenings with their central pores (scrobiculi) located centrally in the front parts of the half-cells (arrows). This ensures identification as variety excavatum.
The cell in frontal view shows a special feature: each chloroplast has two pyrenoids, whereas one central pyrenoid is more common.

The second image shows the state shortly after a cleavage, where one of the two cleavage products has one pyrenoid per chloroplast, the other two plus one (arrows).
The specimens in the two images come from the same sample.

Place name: Wetland Lauchseemoor, Fieberbrunn (Tyrol, Austria)
Latitude: 47.46954439 Longitude: 12.53826499

Microscope Zeiss Universal, camera Olympus OM-D M5 MKII. DOF images.

Sampling date 06/2023. Scale bars indicate 10 µm (1, 2), 25 µm (3, 4).

Four images, three of them in a slide changer.

Please click on < or > on the image edges or on the dots at the bottom edge of the images to browse through the slides!

Place name: Wetland Lauchseemoor, Fieberbrunn (Tyrol, Austria)
Latitude: 47.46954439 Longitude: 12.53826499

Microscope Zeiss Axioplan, camera Olympus OM-D M5 MKII. DOF images.

© Wolfgang Bettighofer,
images under Creative Commons License V 3.0 (CC BY-NC-SA).
For permission to use of (high resolution) images please contact postmaster@protisten.de.