Jaaginema

Taxonomy

Order Leptolyngbyales
Family Leptolyngbyaceae
Genus Jaaginema

Morphology

Trichomes solitary, in tangled clusters, or forming a thin, membrane-like thallus; never motile. Trichomes up to 3 μm wide; usually flexuous; typically unconstricted at crosswalls; sometimes slightly narrowed at the ends; not capitate (not abruptly wider and rounded at the end, as if with a cap on the end); without sheaths, or very rarely with a fine layer of mucilage around trichomes. Cells cylindrical; usually longer than wide (up to 10x longer), only rarely almost isodiametric. Apical cells typically rounded, occasionally conical; without a calyptra; very rarely with a slightly thickened outer cell wall. Cell content homogeneous and without aerotopes; sometimes with a solitary granule on either side of cell crosswalls (clearly visible in the third image to the right: seen in phase contrast, these granules look like white dots, in pairs along the length of the trichome).  

Ecology

Mostly benthic; on sediments or aquatic plants; or in metaphyton. In North America, reported from lakes, rivers, and springs (thermal and mineral). 

Not a very well-studied genus.

References

Johansen, J. R., & Komárek, J. (2015). Filamentous Cyanobacteria. In J. D. Wehr, R. G. Sheath, & J. P. Kociolek (Eds.), Freshwater Algae of North America: Ecology and Classification (2nd ed., pp. 146-148). Waltham, MA: Elsevier.

Komárek, J. & Anagnostidis, K. (2008). Cyanoprokaryota-2. Teil/Part 2: Oscillatoriales. In B. Büdel, G. Gärtner, L. Krienitz, & M. Schagerl (Eds.), Süßwasserflora von Mitteleuropa (Vol. 19/2, pp. 108-117). Heidelberg, Germany: Spektrum.

Strunecký, O., Ivanova, A.P., & Mareš, J. (2023). An updated classification of cyanobacterial orders and families based on phylogenomic and polyphasic analysis. Journal of Phycology, 59: 12-51. https://doi.org/10.1111/jpy.13304