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Molecular characterization of Chlorella cultures of the National Institute for Environmental Studies culture collection with description of Micractinium inermum sp. nov., Didymogenes sphaerica sp. nov., and Didymogenes soliella sp. nov. (Chlorellaceae, Trebouxiophyceae)


  • Communicating editor: O. De Clerck.

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Chlorella Beijerinck (Chlorellaceae, Trebouxiophyceae) strains from the collection of the National Institute for Environmental Studies (NIES) were characterized using gene sequence data. The misidentification of a number of strains was rectified. Chlorella vulgaris Beijerinck NIES-2173 was reclassified as C. sorokiniana Shihira et Krauss. Chlorella sp. NIES-2171 was described as a new species in the genus Micractinium Fresinius, M. inermum Hoshina et Fujiwara. Chlorella sorokiniana NIES-2167 and Chlorella sp. NIES-2330 were found to be phylogenetically related to Didymogenes Schmidle. We propose these two strains be transferred to the genus Didymogenes and given new names: D. sphaerica Hoshina et Fujiwara and D. soliella Hoshina et Fujiwara. Taxonomic decisions were primarily based on small subunit-internal transcribed spacer ribosomal DNA phylogeny for genus assignment and ITS2 sequence-structure to determine species autonomy. Our findings suggest that this strategy is the most effective way to use the species concept among autosporic coccoids.