Cuspidothrix

Taxonomy

Order Nostocales
Family Aphanizomenonaceae
Genus Cuspidothrix

Morphology

Solitary, free-floating filaments; straight or curved, occasionally slightly coiled; cylindrical; sometimes with fine, slimy envelopes, otherwise without sheaths. Trichomes unconstricted to slightly constricted at crosswalls; up to 6 μm wide; distinctly narrowed at the ends, and always sharply to bluntly pointed. Cells cylindrical to nearly barrel-shaped; isodiametric to longer than wide; finely granular cell content; facultative solitary aerotopes. Apical cells narrowed, elongated, and pointed; mostly hyaline. 

Heterocytes solitary and intercalary; cylindrical to ellipsoidal. Akinetes intercalary; solitary, rarely in pairs; either next to or distant from heterocytes; elongated and cylindrical; one or two akinetes per trichome. 

Ecology

Planktic; freshwater; in mesotrophic to eutrophic lakes, ponds, and reservoirs.

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. 183-212). Waltham, MA: Elsevier.

Komárek, J. (2013). Cyanoprokaryota-3. Teil/Part 3: Heterocytous Genera (J. R. Johansen, Ed.). In B. Büdel, G. Gärtner, L. Krienitz, & M. Schagerl (Eds.), Süßwasserflora von Mitteleuropa (Vol. 19/3, pp. 664-672). Heidelberg, Germany: Springer 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