Pseudopediastrum boryanum consists of colonies of four, eight, 16, 32, or 64 cells (termed coenobia), which are arranged in a flat, star-like disc. Coenobia are typically 25–180 μm wide. The inner cells of the coenobium are polygonal, typically 6–20 μm and 5.7–22.5 μm. The marginal cells of the coenobium are typically 8–30 μm and 9–21 μm wide and are slightly to deeply notched, forming two projections; the two projections are up to as long as the rest of the cells and lie parallel to each other.[3] The cell wall is reticulate and is covered in granules situated at the corners of a triangular mesh;[4] it is highly resistant to decay due to the presence of sporopollenin.[5]
Pseudopediastrum boryanum, like related species, typically reproduces asexually by forming zoospores within the parental cell wall; the zoospores then join to form new coenobia. Sexual reproduction occurs and is isogamous, but only occurs rarely.[5]
Throughout its taxonomic history, Pseudopediastrum boryanum (as its synonym, Pediastrum boryanum) has had multiple infraspecific taxa; however, taxonomists differed widely in terms of the number of accepted varieties and relevant morphological features. In 2020, a study found that these varieties constituted a species complex with overlapping morphological characters; the most diagnostic features for distinguishing them are the shape of marginal cells and the density of granules on the cell walls.[2]
Fossil record
The cell walls of Pseudopediastrum boryanum are resistant to decay, and are therefore often found as subfossils in lake sediments.[5] Although Pediastrumsensu lato species are often used as paleoecologicalindicators, P. boryanum is generally not useful as an indicator because it is very common and represents a species complex.[5]
1 2 3 Lenarczyk, Joanna; Saługa, Marta; Piątek, Jolanta (2020). "Integrative Approach Helps Clarify Confusing Taxonomy of the Pseudopediastrum boryanum Species Complex (Chlorophyceae), Including Recognition of five Distinct Species". Journal of Phycology. 56 (6): 1557–1574. doi:10.1111/jpy.13069. PMID32920846. S2CID221672256.
↑ John, David M.; Whitton, Brian A.; Brook, Alan J. (2021). The Freshwater Algal Flora of the British Isles (2ed.). Cambridge University Press. p.896. doi:10.1017/CHOL9781108784122. ISBN978-1-108-78412-2.
1 2 3 4 Komárek, Jirí; Jankovská, Vlasta (2001). Review of the Green Algal Genus Pediastrum; Implication for Pollen-analytical Research. Bibliotheca Phycologica. Schweizerbart Science Publishers. p.127. ISBN978-3-443-60035-8.
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