Two species of the filamentous desmid Hyalotheca

[tlansing]

I have been seeing Hyalotheca in large numbers in my recent collections. This is a filamentous desmid in which individual desmid cells stack one on top of the other to produce long filaments. Hyalotheca is also distinguished by having a thick mucilaginous sheath surrounding the cell body and there are pores in this sheath. In the photo below, I show two different species of Hyalotheca, The one on the top is H. dissiliens and the one below it is H. mucosa. Note the difference in the thickness of the mucilaginous sheath between the two species and the size of the cells. What I find particularly interesting is that I have never seen any protist or algae/diatoms that are able to attach to this sheath. Photo taken at 16x, 1.6x optovar (DIC) on a Zeiss Photomicroscope III. Camera is a Canon 1300D, with flash.

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