What was the color of the filaments? The dimension of the cells suggest a member of Klebsormidium genus. But it could be something else. Was there false branching visible? How was basal like? And the apical cell?
I can try to identify this specimen if you provide me with these details if possible.
If you look closely then the reticulated distribution of the pyrenoids and the presence of one apical cap like structure is evident. Based on these, the specimen should belong to Oedogoniales order. But to be certain some more scrutiny must be done.