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# Validation of ‘Picochlorum costavermella Hemon & Grimsley’ nom. inval. (Trebouxiophyceae) isolated from the northwestern Mediterranean Sea.

Marc Krasovec, Emmelien Vancaester, Stephane Rombauts, François

Bucchini, Sheree Yau, Claire Hemon, Marie-Line Escande, Hugo

Lebredonchel, Nigel Grimsley, Herve Moreau, et al.

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## To cite this version:

Marc Krasovec, Emmelien Vancaester, Stephane Rombauts, François Bucchini, Sheree Yau, et al. Validation of ‘Picochlorum costavermella Hemon & Grimsley’ nom. inval. (Trebouxiophyceae) isolated from the northwestern Mediterranean Sea. Notulae algarum, 2023, 2023, pp.285. hal-04295862

HAL Id: hal-04295862

https://hal.science/hal-04295862v1

Submitted on 20 Nov 2024

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Validation of 'Picochlorum costavermella Hemon & Grimsley' nom. inval. (Trebouxiophyceae) isolated from the northwestern Mediterranean Sea.

Marc Krasovec ¹, Emmelien Vancaester ²,³, Stephane Rombauts ²,³, François Bucchini ²,³, Sheree Yau¹, Claire Hemon ¹, Marie-Line Escande ⁴, Hugo Lebredonchel ¹, Nigel Grimsley ¹, Hervé Moreau ¹, Sophie Sanchez-Brosseau ¹, Klaas Vandepoele ²,³,⁵ & Gwenael Piganeau¹

¹ Sorbonne Université, CNRS, Biologie Integrative des Organismes Marins, BIOM, F-66650 Banyuls-sur-Mer, France.

² Department of Plant Biotechnology and Bioinformatics, Ghent University, Belgium.

³ VIB Center for Plant Systems Biology, Ghent, Belgium.

⁴ Sorbonne Université, CNRS, Observatoire Oceanologique de Banyuls sur mer, FR3724, F-66650 Banyuls-sur-Mer, France.

⁵ Bioinformatics Institute Ghent, Ghent University, Belgium.

Correspondence : gwenael.piganeau@obs-banyuls.fr

Krasovec & al (2018: 2351) described the cell structure and the nuclear mitochondrial and chloroplast genomes of a novel alga of the genus *Picochlorum* (*incertae sedis*, *Trebouxiophyceae*). As the sequence of the molecular 18S rDNA marker was markedly different from the sequence of all previously described *Picochlorum* species (Henley & al. 2014; Yamamoto & al. 2003), they proposed "*Picochlorum costavermella*" Hemon & Grimsley, *sp. nov.*, but this designation was nomenclaturally invalid as a type was not indicated.

*Picochlorum costavermella* Hemon & Grimsley, *sp. nov*.

Description: Non-flagellate small ovoid single cell of 1–2 µm long and 1 µm wide with a 70-nm trilaminar cell wall. Cell contains a single chloroplast and one mitochondrion. The sequence of its 18S rDNA gene is 1,791 bp in length and unique. Phylogenetic analysis using the 18S rDNA gene sequence within the *Picochlorum* genus revealed its closest relative to be *Picochlorum maculatum* found in the East Atlantic Ocean³. The genome is haploid, of 13.3 Mb length, containing 9,304 coding genes and has a 46.1% Guanine-Cytosine content.

Holotype: resin block with glutaraldehyde-fixed representative cells (and thus in a metabolically inactive state) from Roscoff Culture Collection strain number RCC4223 deposited at **PC** (0677382).

Type locality: estuary of the La Massane river in 2011 (42°32′36″ N, 3°03′09″ E, NW Mediterranean Sea, France).

Representative illustration: Krasovec & al. (2018: fig. 1C).

Habitat: Halotolerant and able to grow from 10–70 g/L of salinity.

Registration: http://phycobank.org/103832.

Representative culture: Living culture maintained in L1 medium is available from the Roscoff Culture Collection strain number RCC4223.

Distribution: *Picochlorum costavermella* 18S rDNA gene was detected in metagenomes from the Leucate lagoon (42°50′52″ N, 2°59′47″ E, NW Mediterranean Sea, France) and the two marine stations SOLA (42°29′30″ N, 03°08′70″ E, NW Mediterranean Sea, France) and MOLA (42°27′20″ N, 03°32′60″ E, NW Mediterranean Sea, France).

Etymology: The species epithet is a noun in apposition derived from "Côte Vermeille" in French and "Vermillion Coast" in English, the name of the coast from where the species was isolated. As a noun, it is non-declinable.
Henley, W.J., Hironaka, J.L., Guillou, L., Buchheim, M.A., Buchheim, J.A., Fawley, M.W. & Fawley, K.P. (2004). Phylogenetic analysis of the 'Nannochloris-like' algae and diagnoses of *Picochlorum oklahomensis* gen. et sp. nov. (Trebouxiophyceae, Chlorophyta). *Phycologia* 43(6): 641–652, 15 figs, 1 table.

Krasovec, M., Vancaester, E., Rombauts, S., Bucchini, F., Yau, S., Hemon, C., Lebredonchel, H., Grimsleu, N., Moreau, H., Sanchez-Brosseau, S., Vandepoele, K. & Piganeau, G. (2018). Genome analyses of the microalga *Picochlorum* provide insights into the evolution of thermotolerance in the green lineage. *Genome Biology and Evolution* 10(9): 2347–2365, 4 figs.

Yamamoto, M., Nozaki, H., Miyazawa, Y., Koide, T. & Kawano, S. (2003). Relationship between presence of a mother cell wall and speciation in the unicellular microalga *Nannochloris* (Chlorophyta). *Journal of Phycology* 39(1): 172–184.