Taxonomic and Ecological Characterization of Stomatocysts of Spumella-Like Flagellates (Chrysophyceae)1

Abstract

Cyst formation is a characteristic feature of chrysophytes. Cyst morphology is used for species identification, and the distribution of cysts in sediment cores is used to infer past climate conditions. The affiliation of stomatocyst demes with morphospecies, however, remains unclear. Here, we investigated the taxonomic and ecological value of the occurrence of cyst formation and cyst morphology to differentiate chrysophyte flagellates of the Spumella-morphodeme, which are among the numerically dominant eukaryotes in many aquatic and terrestrial habitats. In the investigated 90 strains of Spumellalike flagellates, we observed encystment only in six strains despite the broad range of temperature regimes and chemical factors tested. Spumella-like flagellates that produce cysts are affiliated with different subclusters within the Chrysophyceae and are closely related to strains for which cyst formation is not known. The occurrence of cyst formation is therefore unsuitable as a taxonomic criterion. Cyst morphology allows for differentiating some strains even though distinctly different strains may have similar or even identical-looking cyst demes. Despite considerable changes in cell size of the vegetative cells related to the nutritional status, the size of the cysts was always larger than that of a typical vegetative cell. Cysts were colorless and had no chromatophores, and some granula were visible in the light microscope. None of the investigated strains and none of the so far published cyst descriptions of Spumella spp. entirely seem to match the cyst description of the generic type strain. However, taking methodological bias between light and electron microscopical investigations into account, the cysts 199hm (this paper) and N1846 (Yubuki et al. 2008 seem to correspond to the cyst of the generic type strain. We propose the strain 199hm as epitype for Spumella vulgaris Cienkowsky; we further describe Spumella rivalis Boenigk et Findenig sp. nov., Pedospumella encystans Boenigk et Findenig gen. et sp. nov., and Poteriospumella lacustris Boenigk et Findenig gen. et sp. nov.

Diversity and geographical distribution of resting stages of eukaryotic algae in the surface sediments from the southern Chinese coastline based on metabarcoding partial 18S rDNA sequences

“…Cyst formation is a characteristic feature of chrysophytes, and Pe. encystans was observed to form cyst under the laboratory conditions (Findenig, Chatzinotas, & Boenigk, 2010). The global ubiquity and abundant distribution of Paraphysomonas was regarded as the amplification by periodic cyst production (Finlay & Clarke, 1999).…”

Genome size of chrysophytes varies with cell size and nutritional mode

“…Mixotrophic strains (mostly affiliated with the genera Dinobryon) are assigned to the Ochromonadales, as are most of the investigated heterotrophic chrysophyte strains. The investigated heterotrophic chrysophyte strains comprise representatives of various genera, e.g., Spumella, Pedospumella, or Segregatospumella (Findenig et al 2010;Grossmann et al 2016).…”

“…Phototrophic strains were grown in 500 mL TC-flasks, heterotrophic strains in 30-mL TC-flasks with bacteria supplied (Limnohabitans planktonicus; strain IID5 T ). Bacteria cultures were raised on 3 g L −1 NSY medium and (Findenig et al 2010) JBC|S 23…”

Effects of short-term flooding on aquatic and terrestrial microeukaryotic communities: a mesocosm approach

“…Many protist and microfungi taxa, e.g. chrysophytes, ciliates, oomycetes and chytridiomycetes, indeed occur in both habitat types (Wong et al 1998, Boenigk et al 2005, Shearer et al 2007, Foissner et al 2008, Findenig et al 2010, Blackwell 2011. Nevertheless, microeukaryotic communities distinctly differ between freshwater and terrestrial habitats (Grossmann et al 2016).…”