Unknown Diatom

Ron Neumeyer · Post by **Ron Neumeyer** » Mon Jul 29, 2013 4:51 pm

Hi - I have a pond sample with a large number of a very interesting diatom. So far I have been unable to id it - any suggestions?
The phase contrast picture was taken with a Plan-Neofluar multi-immersion 40x/0.90 objective and 10x eyepiece.

pwnell · Post by **pwnell** » Mon Jul 29, 2013 10:23 pm

I presume pond implies fresh water?

René · Post by **René** » Tue Jul 30, 2013 3:15 am

hi Ron, looks like Ceratoneis closterium (group), very common. Impossible to positvely ID without further treatment.

Greetingd, René

Ron Neumeyer · Post by **Ron Neumeyer** » Wed Jul 31, 2013 4:45 pm

Waldo - I think it was a freshwater pond; however it was in a wooded area between the dike and the sea (Mud Bay), so it may have been brackish. I returned after a few sunny warm days and it was gone (at high tide).

René thanks for the id. I found the extended apices to be unusual, so am no sure it is a species of Ceratoneis. Checked another reference and think it may be a species of Nitzschia. Is that a possibility?

All the best,
Ron

René · Post by **René** » Thu Aug 01, 2013 4:50 am

Hi Ron,

Sure, part of the 'group'. Lousy not to be able to see more than that, for a taxonomist. In Ceratoneis, the two raphes swirl around eachother. Typically in the smallest forms, they show these 'inflated' ends. Annoying for identification: when prepared in slides the traditional way, the whole structure falls apart in long strips of next to nothing.

Best wishes, René