Pleurotaenium and Desmids

After a week observing algae under the microscope, I've came across numerous algae which share similarity with chain diatoms, but I don't feel these are the same. There are always two sections to this algae strand, and today I caught this particular organism moving itself, similar to euglena (wmv, 10804 k), except the body is not flexible and does not bend. I'm still unclear on the precise identification but feel it must be related, if only distantly to this particular species (below).

A Desmid - Pleurotaenium sp. Found in Sheepwater. It is a green alga, and the wavy lines in the middle distinguish this from other desmids. (x400) Photo: 21st April 2006.
Source: Freshwater and Terrestrial Algae

Example one from my algae sample

Original high resolution image
Approx. 400x magnification w/ digital camera

Gamophyceae: Zygnematales: Desmidiaceae
Pleurotaenium
Nägeli
Genus: Cell body long cylindroid; a slight constriction at center; cross section of the semicells spherical, slightly swell at the center but without a folded structure as Docidium; slightly tapered toward both ends, which are truncated and smooth or surrounded by granules or various small structures; laterally straight or wavy, with spiny projections in some species; 2-10 ribbon-like chloroplasts in each semicell; with many pyrenoids; a vacuole containing active granules at both ends same as in Closterium; cell wall mostly dotted, but with spines or other patterns in some species (Illustrations of The Japanese Fresh-water Algae, 1977).
From Pleurotaenium, Protist Images

Google images contains numerous specimen with likeness and similarity.



Revista Brasileira de Biologia
Desmids, and specifically Pleurotaenium, see diagram in middle of the page.
"Figs. 17-19 – Pleurotaenium eherenbergii var. eherenbergii; Figs. 20-22 – Pleurotaenium trabecula var. elongatum"

Enlarged Image
Example two from my algae sample
Approximate 100x magnification
A similar algae, is the Gonatozygon and here. Some algae groups which share resemblance with my samples, are also available under Desmids

Desmids can be recognised by their symmetry. Two, mostly ornamented semi-cells are joined by a narrow connection called the isthmus. This where the spherical nucleus is situated. Each semi-cell houses a large, often folded chloroplast. One or more pyrenoids can be found. These form carbohydrates for energy storage.
[A specimen very similar to mine, is located under "Where can you find Desmids?"]
DESMIDS by Wim van Egmond

Enlarged Image
Example three from my algae sample
Approximate 1000x magnification w/ digital camera

Enlarged Image
Example four from my algae sample
Approximate 40x magnification

More high resolution images, available here.