Taxonomic reassignment of Pseudohaptolina birgeri comb. nov. (Haptophyta)

ABSTRACT

The haptophyte genus Pseudohaptolina (formerly Chrysochromulina clade B1-3) currently harbours two species: Pseudohaptolina arctica and Pseudohaptolina sorokinii. In addition, Chrysochromulina birgeri is expected to belong to this genus due to its morphological similarity to P. sorokinii, but it has not yet been genetically characterised. A strain belonging to Pseudohaptolina was brought into culture from Arctic waters, characterised by 18S and 28S rRNA gene sequencing as well as optical and transmission electron microscopy, and deposited in the Roscoff Culture Collection with the code RCC5270. Molecular and morphological data from RCC5270 were compared with those from previously described Pseudohaptolina and Pseudohaptolina-like species. Strain RCC5270 showed strong phylogenetic affinity to P. sorokinii, but observations using transmission electron microscopy (TEM) showed that RCC5270 possesses three types of organic body scales, rather than two as originally described for P. sorokinii. We found that the occurrence of three scale types is likely to have been overlooked in the original descriptions of both P. sorokinii and C. birgeri. We also found that environmental metabarcodes identical to the sequence of RCC5270 were abundant at the location from which C. birgeri was initially described (Gulf of Finland). We conclude that P. sorokinii and C. birgeri are conspecific and P. sorokinii is therefore synonymous with C. birgeri. Based on its phylogenetic placement and nomenclatural priority, we propose the new combination Pseudohaptolina birgeri and emend the description of this species.

KEYWORDS:

• Arctic phytoplankton
• Chrysochromulina birgeri
• Organic body scale
• Pseudohaptolina

ACKNOWLEDGEMENTS

We are grateful to Sophie Le Panse from the Merimage microscopy platform at the Roscoff Marine Station for assistance with the transmission electron micrographs and to the Roscoff Culture Collection for maintenance of the algal strain.

DATA ACCESSIBILITY STATEMENT

Supporting data have been deposited to GitHub: https://github.com/vaulot/Paper-2020-Ribeiro-Pseudohaptolina.

SUPPLEMENTARY MATERIAL

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

Additional information

Funding

This work was supported by the GreenEdge project (Fondation Total & ANR, under Grant ANR-14-CE01-0017); the ANR PhytoPol under Grant ANR-15-CE02-0007; and TaxMArc (Research Council of Norway, under Grant 268286/E40). ALS was supported by the Singapore Ministry of Education, Academic Research Fund Tier 1 (RG26/19). CGR was supported by the FONDECYT project number 3190827.