| Abstract: | The extremophilic red algae, Cyanidiales, have long attracted many research attentions due to their highly potential biotechnological applications. Although high genetic diversity has been previously revealed, a further systematic taxonomic re-examination with a more comprehensive taxon sampling is still largely unexplored. To this end, I re-examined their taxonomy and species diversity with the integration of morphological, physiological, and multilocus evidence based on 21 strains distributed around the world. Using seven genetic markers from plastid (psaA, psbA, rpoC1, dnaK, and rbcL) and mitochondrion (cox1 and cox2) for phylogenetic analyses, my study revealed at least 15 species in Cyanidiales that has been previously overlooked. Combining morphological (length, width, cell size, and the number of endospore), physiological (the effect of light and exogenous glucose on the growth rate and lipid content), and ecological features (the occurred microhabitats), my study showed that (1) Galdieria maxima should be transferred to the genus Cyanidioschyzon as Cd. maximum (Sentova) Huang et Liu comb. nov.; (2) all commonly used taxonomic characters failed for the species identification without the molecular assistance. With a better understanding of the taxonomic diagnosis in Cyanidiales, this study not only molecularly revealed their hidden cryptic species, but also provides more phenotypic information that further future taxonomic works in Cyanidiales. |
