Brasilonema

Taxonomy

Order Nostocales
Family Scytonemataceae
Genus Brasilonema

Morphology

Thallus consists of filaments growing in erect fascicles, attached to substrates, forming bristle-like tufts or woolly or velvety layers. Filaments typically 7-26 μm wide; rarely heteropolar (Villanueva et al., 2018); sometimes with slight tapering towards ends. Sheaths present, thin or sometimes slightly thickened, colorless or yellowish-brown, sometimes indistinctly lamellated. Filaments with false branching; branches either single or paired. Trichomes cylindrical, unconstricted or slightly constricted at cell crosswalls. Cells shorter than wide to isodiametric or slightly longer than wide; especially short towards apical ends of trichomes and in hormogonia. Apical cells rounded. 

Cell content is granular and ranges in color from reddish-purple to purplish-grey, blue-green, or olive-green. The presence of vacuole-like structures within cells is a distinguishing feature of this genus (Barbosa et al., 2021). These empty spaces within the cell content may be very large (occupying a significant portion of the cell’s volume) and are often present in rows of cells within parts of a trichome; though described as “vacuole-like,” these structures are unlike true vacuoles, which are membrane-bound organelles found in eukaryotic cells (Fiore et al., 2007).

Heterocytes solitary, intercalary; may be shorter than wide and discoid, or longer than wide and cylindrical, or rounded, hemispherical, or spherical. Akinetes not present. Reproduction by motile hormogonia; hormogonia isopolar, sometimes attached to the mature trichome, sometimes “C”-shaped or crescent-shaped.

Ecology

Interestingly, Brasilonema is known as a subaerophytic or aerophytic genus with a tropical to subtropical distribution (Barbosa et al., 2021). Some examples of where Brasilonema has been found include wet limestone walls in Mexico (Becerra-Absalón et al., 2013), a granite headstone in Jacksonville, Florida, USA (Villanueva et al., 2018), and on the leaves of bromeliads in Brazil (Fiore et al., 2007). Romanenko et al. (2020) also found this genus growing on plants in a tropical greenhouse in Ukraine; the authors in this case suggest that the Brasilonema population likely hitched a ride to the greenhouse on plants which were collected in Brazil and then brought to Ukraine by botanists.

Thus, it was something of a surprise when Brasilonema turned up in a water sample collected from a creek in temperate New Jersey, USA! The sample was collected in July 2020, from a shallow creek near Montclair State University (the home of NJCWST). The genus was not observed in the sample at the time of collection, and was later found growing amongst other algae after the sample container had been left in a growth chamber for roughly two months. 

References

Barbosa, M., Berthold, D.E., Lefler, F.W., & Laughinghouse, H.D. (2021). Diversity of the genus Brasilonema (Nostocales, Cyanobacteria) in plant nurseries of central Florida (USA) with the description of three new species: B. fioreae sp. nov., B. santannae sp. nov. and B. wernerae sp. nov. Fottea, 21(1): 82-99.

Becerra-Absalón, I., Rodarte, B., Osorio, K., Alba-Lois, L., Segal-Kischinevzky, C., & Montejano, G. 2013. A new species of Brasilonema (Scytonemataceae, Cyanoprokaryota) from Tolantongo, Hidalgo, Central Mexico. Fottea, 13(1): 25–38.

Fiore, M.F., Sant'Anna, C.L., de Paiva Azevedo, M. T., Komárek, J., Kaštovský, J., Sulek, J. & Lorenzi, A.S. (2007). The cyanobacterial genus Brasilonema, gen. nov., a molecular and phenotypic evaluation. Journal of Phycology, 43: 789-798.

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. 183-184). Waltham, MA: Elsevier.

Romanenko, P.A., Vinogradova, O.N., Romanenko, E.A., Mikhailyuk, T.I., Babenko, L.M., Ivannikov, R., & Scherbak, N.N. (2020): Morphological and molecular characterization of the representative of Brasilonema (Scytonemataceae, Cyanoprokaryota) from the tropical greenhouse in Kiev (Ukraine). – International Journal on Algae, 22: 103–122.

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

Villanueva, C.D., Hašler, P., Dvořák, P., Poulíčková, A. & Casamatta, D.A. (2018), Brasilonema lichenoides sp. nov. and Chroococcidiopsis lichenoides sp. nov. (Cyanobacteria): two novel cyanobacterial constituents isolated from a tripartite lichen of headstones. Journal of Phycology, 54: 224-233.