New and little-known freshwater chrysophytes, including a description of Randersenia wujeki gen. et sp. nov. (Chrysophyceae)
Nicholls, Kenneth H.
Five unusual chrysophyte species were discovered in dilute softwater lakes and streams in Ontario, Canada. Only one of these (Heimiochrysis actinotrichia Bourrelly) had been previously described and is known only from single locations in France and Sweden. Three of the Ontario entities are described here as new species: Rhizochrysis splendida n. sp., Chrysapion asymmetricum n. sp., and Randersenia wujeki n. gen. et n. sp. A fifth species is most likely a previously undescribed species of Lepidochrysis; it is about 2x larger than the only other known species of this genus, the marine L. glomerifera (Clarke & Pennick) Ikävalko, Kristiansen & Thomsen. The Ontario Lepidochrysis was found in a freshwater lake and included a covering of scales that were also about 2x larger, but otherwise similar in structure to those of the marine species. The Ontario Lepidochrysis was not formally assigned new species status at this time because no information on cell organelles (chloroplast, contractile vacuoles, etc.) is presently available. Randersenia n. gen. is a unique genus of heterokont (but non-motile) chrysophyte forming macroscopic mucilaginous colonies attached to submerged plant stems and other substrates. It differs from other similar genera, such as Mucosphaera Dop & Van Beem, Saccochrysis (Korshikov) Andersen, Hibberdia Andersen and Chrysonephele Pipes, Tyler & Leedale by the presence in Randersenia of a pyrenoid and the nearly perpendicular insertion of its flagella.