Revealing hidden diversity in the Cryptomonas erosa clade (Cryptophyceae), with the description of two new species from acidic habitats

ABSTRACT

In this study, the cryptomonads of the northern territories of Russia were explored. Four strains were isolated from the different acidic habitats in the Middle Urals and the North of the European part of Russia. Cells of these strains are flattened in the dorsoventral plane, have an asymmetrical outline and are similar in size and shape to Cryptomonas erosa. Phylogenetic relationships inferred using maximum likelihood and Bayesian interference from datasets of nuclear-encoded SSU, LSU, ITS2 rDNA and psbA cpDNA show that the strains form one clade, which was divided into three subclades with high statistical support. One subclade was attributed to Cryptomonas erosa. Two other subclades represent species new to science. Comparison of ITS2 rRNA secondary structures with the compensatory base changes (CBC) approach confirmed the separation between C. erosa and the two new species, C. macilenta sp. nov. and C. parmana sp. nov. Comparison of nuclear V9 SSU and ITS1 rDNA sequences of two new species with metabarcoding data from 218 lakes in Europe showed that C. macilenta and C. parmana have not previously been recorded in Europe.

KEYWORDS:

• Compensatory base changes
• Cryptomonas macilenta
• Cryptomonas parmana
• ITS2 rRNA secondary structure
• LSU rDNA and psbA markers
• SSU rDNA

ACKNOWLEDGEMENTS

We thank L.N. Rybin for his help in creating a map. We also thank two anonymous reviewers for helpful comments.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

SUPPLEMENTARY MATERIAL

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This study was supported by RFBR grant № 18-04-01280_а and was performed in accordance with the framework of the state assignment of Ministry of Science and Higher Education of the Russian Federation (themes No. 121041200194-7 for IPP RAS and 1021051101424-8-1.6.11;1.6.19;1.6.20 for Institute of Biology Komi SC UB RAS).