Anila:

Must provide a scale. Shows affinity with Actinotaenium globosum (Bulnheim).

Best

Syed

I don't think it is Actinotaenium globosum 

Jackson:

Merely affinity with A. globosum was indicated. Would you kindly suggest accurate identification?

Best

Syed

I am doubting it. Looking at the somewhat deeper indentation in the middle, it may be Cosmarium cucurbita

Thanks a lot for the suggestions. 

Dear Dr Jafar, .Cells 48-22 μm (LxB)

Dr Jan, The deeper constriction at the center is making confusion. ! 

Dear Anila  my suggestion is   Actinotaenium curtum (Ralfs) Teiling

Features : Cells 18-32 μm wide and 22-66  μm long,with broadly rounded apices,slight internal apical thickening, No puncta at Isthmus, chloroplast with longitudinal ridges.

Good luck!

Thank you Sir. 

Anila:

It does not seem to match morphology of A. curtum (pl. see link):

http://www.desmids.nl/maand/english/actinotaenium_curtum.html

Best

Syed

That's very true Dr Jafar. But, do morphological similarity is so much important? (just for a clarification !) 

Dear Anila,

I partially agree with Dr.Jafar because the cell (-chloroplast) has undergone slight morphological changes.Look at two cells in the page for reference added by Dr.jafar, the chloroplasts of those cells  could be interpreted as two different types.

In my opinion it even depends on the plane or the way the cell is oriented while photographing.

Anila, your doubt is relevant! Chloroplast can undergo slight variation/distortion as we delay the microscopic analysis and I don't think we can make  a confirmation on those morphological deviations due to preservative or stain or whatever.

If you want to know it for yourself by observing any green alga(say for example  Spirogyra.) you collected after few days of storage. So it is always advisable to go for the microscopic analysis at the earliest you can at least within 24 hours of collection,which will give you an original  picture of the cell morphology.Try to follow this in your future studies.

Good luck!

Anila:

Morphological similarity and identity of species should be established on the basis of several specimens, varied focus under LM, ultrastructure based on SEM studies and molecular genetics.

Best

Syed

Well, Thank you Dr Jackson and Dr Jafar for the suggestions and clarifications. 

Dear Anila,

The genus Actinotaenium was separated from Cosmarium by Teiling (1954) on the basis of the following morphological characteristics: omniradiate cells with circular apical view, very shallow, open sinus and stelloid or asteroid or, more rarely, parietal chloroplast(s) (see, e.g., Ruzicka 1981). Your material shows a closed (albeit shallow)sinus and obviously a furcoid (albeit somewhat deformed due to fixation) chloroplast. The picture doesn't show the apical view but I don't think it is circular (but it might be subcircular!).

In conclusion: your specimen most probably concerns a Cosmarium species.

By the way: Cosmarium cucurbita suggested by Jan Rijstenbil currently is also classified in the genus Actinotaenium.

Dear all, "Cosmarium maculatum forma Turner 1892 "  - 

as made a possibility by  Dr Peter  Coesel

University of Amsterdam. 

Thank you all...

Regards

Anila Ajayan

Anila:

You may like to have a look at this link. It is possibly Cosmarium maculatiforme Schm.:

http://lib.icimod.org/record/13395/files/6172.pdf

Best

Syed

Dear Dr Jafar,

Still Confusions... 

The length and width does not getting in agree.....

Anila:

There should not be much confusion as the Length/Width of your documented specimen closely matches with the specimen illustrated in the link. Moreover, you should be having access to several specimens wherein you could observe apical view (circular or elliptical) and closely observe nature of cell and chlroplasts etc. for identification.

Best

Syed

Thank you so much Dr Syed Abbas Jafar. I will keep in mind your suggestions.!

Regards

Anila Ajayan 

As pointed out by previous experts it is certainly not from the genus Actinotaenium. It also seems to be similar to C. tumescens Turner 1892, which Turner suggests comparing with C. maculatum in the same paper. Based on the morphology from the picture provided, this specimen is also most likely a tychoplankter.

Regards,

Alex.