<i>Lunachloris lukesovae</i> gen. et sp. nov. (Trebouxiophyceae, Chlorophyta), a novel coccoid green alga isolated from soil in South Bohemia, Czech Republic

<p>Culture collections of microorganisms can still hold undiscovered biodiversity; with molecular techniques, considerable progress has been made in characterizing microalgae which were isolated in the past and misidentified due to a lack of morphological features. However, many strains are still awaiting taxonomic reassessment. Here we analysed the phylogenetic position, morphology and ultrastructure of the strain CCALA 307 previously identified as <i>Coccomyxa</i> cf. <i>gloeobotrydiformis</i> Reysigl isolated in 1987 from field soil in South Bohemia, Czech Republic. Molecular phylogenetic analyses based on SSU rDNA and the plastid <i>rbc</i>L gene revealed that the strain CCALA 307 formed a distinct sister lineage to <i>Neocystis</i> and <i>Prasiola</i> clades within the Trebouxiophyceae. We describe this strain as a new genus and species, <i>Lunachloris lukesovae</i>. Multiple conserved nucleotide positions identified in the secondary structures of the highly variable ITS2 rDNA barcoding marker provide further evidence of the phylogenetic position of <i>Lunachloris</i>. Minute vegetative cells of this newly recognized species are spherical or ellipsoid, with a single parietal chloroplast without a pyrenoid. Asexually, it reproduces by the formation of 2–6 autospores. Since the majority of recent attention has been paid to algae from the tropics or extreme habitats, the biodiversity of terrestrial microalgae in temperate regions is still notably unexplored and even a ‘common’ habitat like agricultural soil can contain new, as yet unknown species. Moreover, this study emphasizes the importance of culture collections of microorganisms even in the era of culture-independent biodiversity research, because they may harbour novel and undescribed organisms as well as preserving strains for future studies.</p

Ecophysiological and morphological comparison of two populations of <i>Chlainomonas</i> sp. (Chlorophyta) causing red snow on ice-covered lakes in the High Tatras and Austrian Alps

<p>Based on analyses of multiple molecular markers (18S rDNA, ITS1, ITS2 rDNA, <i>rbc</i>L), an alga that causes red snow on the melting ice cover of a high-alpine lake in the High Tatras (Slovakia) was shown to be identical with <i>Chlainomonas</i> sp. growing in a similar habitat in the Tyrolean Alps (Austria). Both populations consisted mostly of smooth-walled quadriflagellates. They occurred in slush, and shared similar photosynthetic performances (photoinhibition above 1300 µmol photons m^–2 s^–1), very high levels of polyunsaturated fatty acids (PUFA, 64% and 74% respectively) and abundant astaxanthin accumulation, comparable to the red spores of <i>Chlamydomonas nivalis</i> (Bauer) Wille. Physiological differences between the Slovak and Austrian populations included higher levels of α-tocopherol and a 13Z-isomer of astaxanthin in the former. High accumulation of secondary pigments in the Slovak population probably reflected harsher environmental conditions, since the collection was made later in the growing season when cells were exposed to higher irradiance at the surface. Using a polyphasic approach, we compared <i>Chlainomonas</i> sp. with <i>Chlamydomonas</i> <i>nivalis</i>. The latter causes ʻconventionalʼ red snow, and shows high photophysiological plasticity, with high efficiency under low irradiance and no photoinhibition up to 2000 µmol photons m^–2 s^–1. Its PUFA content was significantly lower (50%). An annual cycle of lake-to-snow colonization by <i>Chlainomonas</i> sp. from slush layers deeper in the ice cover is proposed. Our results point to an ecologically highly specialized cryoflora species, whose global distribution is likely to be more widespread than previously assumed.</p